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Total synthesis of specialized pro-resolving lipid mediators and their analogs

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Total synthesis of specialized pro-resolving lipid mediators and their analogs

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Content Total Synthesis of Specialized Pro-resolving Lipid Mediators and
Their Analogs
by

Nikita A. Vlasenko

A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMISTRY)

August 2016

Copyright 2016 Nikita A. Vlasenko
2

Dedication

To my mother Kate

3

Acknowledgements

First and foremost I would like to thank my mentor Nicos Petasis for letting me work with
the research projects I was most interested in. His guidance through my graduate school was
immensely important and helped me to achieve my goals.
I would like to thank my undergraduate advisor, Professor Mikhail Kuznetsov for his wise
advice that he gave me throughout my graduate research.
I would like to thank my group members who taught me the skills that I have now, and
who worked closely with me at the very beginning of my graduate school. I would like to thank
other group members for making me feel comfortable working with them, creating the atmosphere
of mutual help and advice.

4

Table of Contents
Dedication .......................................................................................................................................2
Acknowledgements ........................................................................................................................3
Table of Contents ...........................................................................................................................4
List of Schemes ...............................................................................................................................6
List of Figures (Spectra) ................................................................................................................8
Abstract .........................................................................................................................................14
Chapter 1 ......................................................................................................................................15
1.1 Introduction ..........................................................................................................................15
Chapter 2: Total Synthesis of Resolvins (RvD5 and ATRvD2) ...............................................19
2.1 Introduction ..........................................................................................................................19
2.2 Results ..................................................................................................................................22
2.2.1 Retrosynthetic Analysis of RvD5 ..................................................................................22
2.2.2 Synthesis of Building Blocks of RvD5 .........................................................................23
2.2.3 Retrosynthetic Analysis of AT RvD2............................................................................33
2.2.4 Synthesis of Building Blocks of AT RvD2 ...................................................................34
2.3 Conclusion ............................................................................................................................38
2.4 Experimental Procedures ......................................................................................................39
2.5 Spectra ..................................................................................................................................62
Chapter 3: Total Synthesis of epoxy lipid mediators ..............................................................121
3.1 Introduction ........................................................................................................................121
3.2 Results ................................................................................................................................125
3.2.1 Retrosynthetic Analysis of the 7R, 8R-epoxide ..........................................................125
3.2.2 Synthesis of Building Blocks of the 7R, 8R-epoxide .................................................126
3.2.3 Retrosynthetic Analysis of the 16S, 17S-epoxy Protectin ...........................................130
3.2.4 Synthesis of Building Blocks of the 16S, 17S-epoxy Protectin...................................131
3.2.5 Retrosynthetic Analysis of the 13S, 14S-epoxy Maresin ............................................133
3.2.6 Synthesis of Building Blocks of the 13S, 14S-epoxy Maresin ...................................134
3.3 Conclusion ..........................................................................................................................136
3.4 Experimental Procedures ....................................................................................................137
3.5 Spectra ................................................................................................................................150
5

Chapter 4: Total Synthesis of the Methyl (4Z,7Z,12E,14S,16Z,19Z,21R)-14,21-
dihydroxydocosa-4,7,12,16,19-pentaen-10-ynoate ..................................................................183
4.1 Introduction ........................................................................................................................183
4.2 Results ................................................................................................................................185
4.2.1 Retrosynthetic Analysis of the Methyl (4Z,7Z,12E,14S,16Z,19Z,21R)-14,21-
dihydroxydocosa-4,7,12,16,19-pentaen-10-ynoate ..............................................................185
4.2.2 Synthesis of Building Blocks of the Methyl (4Z,7Z,12E,14S,16Z,19Z,21R)-14,21-
dihydroxydocosa-4,7,12,16,19-pentaen-10-ynoate .............................................................186
4.3 Conclusion ..........................................................................................................................193
4.4 Experimental Procedures ....................................................................................................194
4.5 Spectra ................................................................................................................................204
Chapter 5: Total Synthesis of the Methyl (5S,6R,E)-5,6-dihydroxy-8-(5-((R,E)-3-
hydroxyoct-1-en-1-yl)thiophen-2-yl)oct-7-enoate (Thiolipoxin) ............................................233
5.1 Introduction ........................................................................................................................233
5.2 Results ................................................................................................................................237
5.2.1 Retrosynthetic Analysis of the Methyl (5S,6R,E)-5,6-dihydroxy-8-(5-((R,E)-3-
hydroxyoct-1-en-1-yl)thiophen-2-yl)oct-7-enoate ...............................................................237
5.2.2 Synthesis of Building Blocks of the Methyl (5S,6R,E)-5,6-dihydroxy-8-(5-((R,E)-3-
hydroxyoct-1-en-1-yl)thiophen-2-yl)oct-7-enoate ...............................................................239
5.3 Conclusion ..........................................................................................................................241
5.4 Experimental Procedures ....................................................................................................241
5.5 Spectra ................................................................................................................................246
Bibliography ...............................................................................................................................253

6

List of Schemes
Scheme 1.1. Simplified scheme of biochemical pathways involved in the inflammatory response
and resolution .................................................................................................................................16
Scheme 1.2. Examples of pro-inflammatory compounds prostaglandin E2 (PGE2) and
leukotriene B4 (LTB4) ...................................................................................................................17
Scheme 1.3. Three major groups of pro-resolving lipid mediators. Example molecules from each
group: RvD1, Mar1, PD1 ...............................................................................................................18
Scheme 2.1. Simplified scheme of the biosynthetic formation of the resolvins ............................19
Scheme 2.2. Structure of AT-RvD2, total synthesis of which is accomplished in the current
dissertation work ............................................................................................................................21
Scheme 2.3. Retrosynthetic scheme of RvD5 methyl ester 2.25 ...................................................22
Scheme 2.4. Synthesis of key intermediate 2.11. ..........................................................................23
Scheme 2.5. Previously utilized approach for the synthesis of compound 2.5 ..............................24
Scheme 2.6. Searching for optimal conditions of the direct synthesis of 2.5 ................................25
Scheme 2.7. Synthesis of key intermediate 2.19. ..........................................................................27
Scheme 2.8. Previously used approach towards Sonogashira reaction with compound 2.17 .......28
Scheme 2.9. Superior copper-free Sonogashira reaction ...............................................................28
Scheme 2.10. Synthesis of 2.20 and attempts for the deprotection ...............................................29
Scheme 2.11. Synthesis of 2.21 and 2.22 ......................................................................................30
Scheme 2.12. Synthesis of 2.23 and failed Boland the reduction ..................................................30
Scheme 2.13. Synthesis of the final RvD5 methyl ester ...............................................................31
Scheme 2.14. The modified Lindlar reaction, the conditions of which we successfully applied to
our synthesis...................................................................................................................................31
Scheme 2.15. Improved Lindlar conditions applied for the hydrogenation of compound 2.20 ....32
Scheme 2.16. Retrosynthetic scheme of AT RvD2 methyl ester 2.43 ...........................................33
Scheme 2.17. Improved synthetic route to the vinyl iodide 2.40 ..................................................34
7

Scheme 2.18. Synthetic scheme of the key intermediate 2.33 .......................................................35
Scheme 2.19. Previously used CSA deprotection of the primary alcohol group ...........................36
Scheme 2.20. The completion of the AT RvD2 methyl ester synthesis ........................................37
Scheme 3.1. (7R, 8R) – Epoxide that was successfully synthesized in the current work ...........121
Scheme 3.2. Simplified biosynthetic pathway for the formation of PD-1/NPD-1 from DHA ....122
Scheme 3.3. (13S,14S)-epoxy maresin intermediacy in the production of Mar1 ........................123
Scheme 3.4. Inhibitory pathways of 13S,14S-epoxy maresin ......................................................124
Scheme 3.5. Retrosynthetic scheme of methyl (Z)-6-((2R,3R)-3-((1E,3E,5Z,8Z,11Z)-
tetradeca-1,3,5,8,11-pentaen-1-yl)oxiran-2-yl)hex-4-enoate ......................................................125
Scheme 3.6. Synthesis of key intermediate 3.10 .........................................................................126
Scheme 3.7. Synthesis of key intermediate – Wittig salt 3.11 .....................................................128
Scheme 3.8. Synthesis of the final 7R, 8R-epoxy methyl ester 3.12 ...........................................129
Scheme 3.9. Retrosynthetic analysis of 16S, 17S-epoxy protectin .............................................130
Scheme 3.10. Synthesis of key intermediate – aldehyde 3.17 .....................................................131
Scheme 3.11. Final Wittig coupling that establishes cis-stereochemistry at 10th position of 3.21
......................................................................................................................................................132
Scheme 3.12. Retrosynthetic scheme of the 13S, 14S – epoxy maresin .....................................133
Scheme 3.13. Synthesis of the key epoxy aldehyde building block 3.29 ....................................134
Scheme 3.14. Synthesis of key Wittig salt 3.37 ...........................................................................135
Scheme 3.15. Final KHMDS-mediated coupling that generates 13S, 14S-epoxy maresin .........136
Scheme 4.1. Biosynthetic scheme of the formation of novel 14,21-diHDHA lipid mediators that
were shown to be extremely important for wound healing process ............................................183
Scheme 4.2. Retrosynthetic analysis of the compound 4.27........................................................185
Scheme 4.3. Synthesis of alcohol 4.7 ..........................................................................................186
Scheme 4.4. Alcohol region of compound 4.15 shows the doubling of carbon signals that is
attributed to the mixture of diastereomers ...................................................................................187
8

Scheme 4.5. Synthesis of the protected diol 4.11 ........................................................................188
Scheme 4.6. Synthesis of the key diol 4.18 .................................................................................189
Scheme 4.7. Synthesis of the methyl ester 4.21 accomplished by Min Zhu................................190
Scheme 4.8. Synthesis of the methyl ester 4.23 ...........................................................................191
Scheme 4.9. Final steps of the synthesis: Sonogashira coupling and failed attepmpt at reducing
10,11 - triple bond of 4.24 ...........................................................................................................191
Scheme 5.1. Two endogenous lipoxins: lipoxin A4 and lipoxin B4 that have potent anti-
inflammatory effects ....................................................................................................................233
Scheme 5.2. Biosynthesis of LXA4 and its epimeric form..........................................................234
Scheme 5.3. Some lipoxin A4 (LXA4) analogs previously synthesized and the anti-inflammatory
properties......................................................................................................................................235
Scheme 5.4. New lipoxin analog synthesized in the current dissertation work. First known
example of a lipoxin analog with a heterocycle in the tetraene moiety ......................................236
Scheme 5.5. Retrosynthetic scheme of the thiolipoxin 5.15 ........................................................237
Scheme 5.6. Synthesis of key vinyl iodide building block 5.7 ....................................................238
Scheme 5.7. Synthesis of the catechol boronate 5.11 ..................................................................239
Scheme 5.8. Synthesis of the final thiolipoxin compound 5.15...................................................240
List of Figures (Spectra)
Figure 2.1:
1
H NMR spectrum of compound 2.4 ...........................................................................62
Figure 2.2:
1
H NMR spectrum of compound 2.5 ...........................................................................63
Figure 2.3:
1
H NMR spectrum of compound 2.6 ...........................................................................64
Figure 2.4:
1
H NMR spectrum of compound 2.7 ...........................................................................65
Figure 2.5:
13
C NMR spectrum of compound 2.7 ..........................................................................66
Figure 2.6:
1
H NMR spectrum of compound 2.8 ...........................................................................67
Figure 2.7:
13
C NMR spectrum of compound 2.8. .........................................................................68
Figure 2.8:
1
H NMR spectrum of compound 2.9 ...........................................................................69
9

Figure 2.9:
13
C NMR spectrum of compound 2.9 ..........................................................................70
Figure 2.10:
1
H NMR spectrum of compound 2.10. ......................................................................71
Figure 2.11:
13
C NMR spectrum of compound 2.10 ......................................................................72
Figure 2.12:
1
H NMR spectrum of compound 2.11 .......................................................................73
Figure 2.13:
13
C NMR spectrum of compound 2.11 ......................................................................74
Figure 2.14:
1
H NMR spectrum of compound 2.18 .......................................................................75
Figure 2.15:
13
C NMR spectrum of compound 2.18 ......................................................................76
Figure 2.16:
1
H NMR spectrum of compound 2.19 .......................................................................77
Figure 2.17:
13
C NMR spectrum of compound 2.19 ......................................................................78
Figure 2.18:
1
H NMR spectrum of compound 2.20 .......................................................................79
Figure 2.19:
1
H NMR spectrum of the olefinic region of compound 2.20 ....................................80
Figure 2.20:
13
C NMR spectrum of compound 2.20 ......................................................................81
Figure 2.21:
1
H NMR spectrum of compound 2.21 .......................................................................82
Figure 2.22:
13
C NMR spectrum of compound 2.21 ......................................................................83
Figure 2.23:
1
H NMR spectrum of compound 2.22 .......................................................................84
Figure 2.24:
13
C NMR spectrum of compound 2.22 ......................................................................85
Figure 2.25:
1
H NMR spectrum of compound 2.23 .......................................................................86
Figure 2.26:
1
H NMR spectrum of the olefinic region of compound 2.23 ....................................87
Figure 2.27:
13
C NMR spectrum of compound 2.23 ......................................................................88
Figure 2.28: 2D
1
H-
1
H COSY NMR spectrum of compound 2.23 ...............................................89
Figure 2.29:
1
H NMR spectrum of compound 2.24 .......................................................................90
Figure 2.30:
1
H NMR spectrum of the olefinic region of compound 2.24 ....................................91
Figure 2.31:
13
C NMR spectrum of compound 2.24 ......................................................................92
Figure 2.32: 2D
1
H-
1
H COSY NMR spectrum of compound 2.24 ................................................93
Figure 2.33:
1
H NMR spectrum of compound 2.25 .......................................................................94
Figure 2.34:
1
H NMR spectrum of the olefinic region of compound 2.25 ....................................95
10

Figure 2.35:
13
C NMR spectrum of compound 2.25 ......................................................................96
Figure 2.36: 2D
1
H-
1
H COSY NMR spectrum of compound 2.25 ................................................97
Figure 2.37: 2D NOESY NMR spectrum of compound 2.25 ........................................................98
Figure 2.38:
1
H NMR spectrum of compound 2.26 .......................................................................99
Figure 2.39:
1
H NMR spectrum of compound 2.27 .....................................................................100
Figure 2.40:
1
H NMR spectrum of compound 2.28 .....................................................................101
Figure 2.41:
13
C NMR spectrum of compound 2.28 ....................................................................102
Figure 2.42:
1
H NMR spectrum of compound 2.29 .....................................................................103
Figure 2.43:
13
C NMR spectrum of compound 2.29 ....................................................................104
Figure 2.44:
1
H NMR spectrum of compound 2.30 .....................................................................105
Figure 2.45:
13
C NMR spectrum of compound 2.30 ....................................................................106
Figure 2.46:
1
H NMR spectrum of compound 2.31 .....................................................................107
Figure 2.47:
13
C NMR spectrum of compound 2.31 ....................................................................108
Figure 2.48:
1
H NMR spectrum of compound 2.32 .....................................................................109
Figure 2.49:
13
C NMR spectrum of compound 2.32 ....................................................................110
Figure 2.50:
1
H NMR spectrum of compound 2.33 .....................................................................111
Figure 2.51:
13
C NMR spectrum of compound 2.33 ....................................................................112
Figure 2.52:
1
H NMR spectrum of compound 2.41 .....................................................................113
Figure 2.53:
13
C NMR spectrum of compound 2.41 ....................................................................114
Figure 2.54:
1
H NMR spectrum of compound 2.42 .....................................................................115
Figure 2.55:
13
C NMR spectrum of compound 2.42 ....................................................................116
Figure 2.56: 2D
1
H-
1
H COSY NMR spectrum of compound 2.42 ..............................................117
Figure 2.57:
1
H NMR spectrum of compound 2.43 .....................................................................118
Figure 2.58:
13
C NMR spectrum of compound 2.43 ....................................................................119
Figure 2.59: 2D
1
H-
1
H COSY NMR spectrum of compound 2.43 ..............................................120
11

Figure 3.1:
1
H NMR spectrum of compound 3.2 .........................................................................150
Figure 3.2:
13
C NMR spectrum of compound 3.2 ........................................................................151
Figure 3.3:
1
H NMR spectrum of compound 3.3 .........................................................................152
Figure 3.4:
13
C NMR spectrum of compound 3.3 ........................................................................153
Figure 3.5:
1
H NMR spectrum of compound 3.4 .........................................................................154
Figure 3.6:
13
C NMR spectrum of compound 3.4 ........................................................................155
Figure 3.7:
1
H NMR spectrum of compound 3.5 .........................................................................156
Figure 3.8:
13
C NMR spectrum of compound 3.5 ........................................................................157
Figure 3.9:
1
H NMR spectrum of compound 3.6 .........................................................................158
Figure 3.10:
13
C NMR spectrum of compound 3.6 ......................................................................159
Figure 3.11:
1
H NMR spectrum of compound 3.7 .......................................................................160
Figure 3.12:
13
C NMR spectrum of compound 3.7 ......................................................................161
Figure 3.13:
1
H NMR spectrum of compound 3.8 .......................................................................162
Figure 3.14:
13
C NMR spectrum of compound 3.8 ......................................................................163
Figure 3.15 :
1
H NMR spectrum of compound 3.9 ......................................................................164
Figure 3.16:
13
C NMR spectrum of compound 3.9 ......................................................................165
Figure 3.17 :
1
H NMR spectrum of compound 3.10 ....................................................................166
Figure 3.18:
13
C NMR spectrum of compound 3.10 ....................................................................167
Figure 3.19 :
1
H NMR spectrum of compound 3.11 ....................................................................168
Figure 3.20:
13
C NMR spectrum of compound 3.11 ....................................................................169
Figure 3.21 :
1
H NMR spectrum of compound 3.12 ....................................................................170
Figure 3.22:
13
C NMR spectrum of compound 3.12 ....................................................................171
Figure 3.23 :
1
H NMR spectrum of compound 3.24 ....................................................................172
12

Figure 3.24 :
1
H NMR spectrum of compound 3.25 ....................................................................173
Figure 3.25:
13
C NMR spectrum of compound 3.25 ....................................................................174
Figure 3.26 :
1
H NMR spectrum of compound 3.26 ....................................................................175
Figure 3.27:
13
C NMR spectrum of compound 3.26 ....................................................................176
Figure 3.28 :
1
H NMR spectrum of compound 3.27 ....................................................................177
Figure 3.29 :
1
H NMR spectrum of compound 3.28 ....................................................................178
Figure 3.30:
13
C NMR spectrum of compound 3.28 ....................................................................179
Figure 3.31 :
1
H NMR spectrum of compound 3.29 ....................................................................180
Figure 3.32:
13
C NMR spectrum of compound 3.29 ....................................................................181
Figure 3.33 :
1
H NMR spectrum of compound 3.30 ....................................................................182
Figure 4.1:
1
H NMR spectrum of compound 4.2 .........................................................................204
Figure 4.2:
13
C NMR spectrum of compound 4.2 ........................................................................205
Figure 4.3:
1
H NMR spectrum of compound 4.3 .........................................................................206
Figure 4.4:
13
C NMR spectrum of compound 4.3 ........................................................................207
Figure 4.5:
1
H NMR spectrum of compound 4.4 .........................................................................208
Figure 4.6:
13
C NMR spectrum of compound 4.4 ........................................................................209
Figure 4.7:
1
H NMR spectrum of compound 4.5 .........................................................................210
Figure 4.8:
13
C NMR spectrum of compound 4.5 ........................................................................211
Figure 4.9:
1
H NMR spectrum of compound 4.6 .........................................................................212
Figure 4.10:
13
C NMR spectrum of compound 4.6 ......................................................................213
Figure 4.11:
1
H NMR spectrum of compound 4.7 .......................................................................214
Figure 4.12:
13
C NMR spectrum of compound 4.7 ......................................................................215
Figure 4.13:
1
H NMR spectrum of compound 4.12 .....................................................................216
13

Figure 4.14:
13
C NMR spectrum of compound 4.12 ....................................................................217
Figure 4.15:
1
H NMR spectrum of compound 4.13 .....................................................................218
Figure 4.16:
1
H NMR spectrum of compound 4.14 .....................................................................219
Figure 4.17:
13
C NMR spectrum of compound 4.14 ....................................................................220
Figure 4.18:
1
H NMR spectrum of compound 4.15 .....................................................................221
Figure 4.19:
13
C NMR spectrum of compound 4.15 ....................................................................222
Figure 4.20:
1
H NMR spectrum of compound 4.16 .....................................................................223
Figure 4.21:
13
C NMR spectrum of compound 4.16 ....................................................................224
Figure 4.22:
1
H NMR spectrum of compound 4.17 .....................................................................225
Figure 4.23:
13
C NMR spectrum of compound 4.17 ....................................................................226
Figure 4.24:
1
H NMR spectrum of compound 4.18 .....................................................................227
Figure 4.25:
13
C NMR spectrum of compound 4.18 ....................................................................228
Figure 4.26:
1
H NMR spectrum of compound 4.23 .....................................................................229
Figure 4.27:
13
C NMR spectrum of compound 4.23 ....................................................................230
Figure 4.28:
1
H NMR spectrum of compound 4.24 .....................................................................231
Figure 4.29:
13
C NMR spectrum of compound 4.24 ....................................................................232
Figure 5.1:
1
H NMR spectrum of compound 5.4 .........................................................................246
Figure 5.2:
1
H NMR spectrum of compound 5.7 .........................................................................247
Figure 5.3:
1
H NMR spectrum of compound 5.13 .......................................................................248
Figure 5.4:
1
H NMR spectrum of compound 5.14 .......................................................................249
Figure 5.5:
1
H NMR spectrum of compound 5.15 .......................................................................250
Figure 5.6:
13
C NMR spectrum of compound 5.15 ......................................................................251
Figure 5.7:
1
H-
1
H COSY NMR spectrum of compound 5.14......................................................252
14

Abstract
Current work provides the accomplished total syntheses of potent pro-resolving anti-
inflammatory lipid mediators to help further biological research in the field.
In Chapter 1 a brief introduction is done into the field of lipid mediators and their
involvement in inflammatory processes.
Chapter 2 discusses the total syntheses of resolvin D5 (RvD5) and aspirin-triggered
resolvin D2 (AT-RvD2) which play significant role in the resolution phase of inflammation with
and without aspirin influence respectively. To accomplish the syntheses new reaction techniques
were developed and already discovered were applied to improve the yields and reduce the number
of steps. Of particular importance is epoxide opening reaction by pentynoic methyl ester the
reaction conditions of which were optimized and helped to cut down the number of steps
significantly; Lindlar hydrogenation that uses 1-octene, copper-free Sonogashira reactions that
were previously reported but never applied to molecules with such complex frameworks.
Chapter 3 talks about epoxy-lipid mediators’ and their total syntheses. Epoxy-maresin1
lipid mediator, synthesized in the current work, helped to further prove the biosynthetic pathway
of maresin1 formation. Other epoxy-lipid mediators discussed may also be used to advance the
elucidation of other similar biosynthetic pathways.
Chapter 4 provides the first attempt at synthesis of 14,21-diHDHA compound that is tightly
involved in wound healing processes. The issues are discussed and the solution is proposed
partially based on found 1-octene Lindlar hydrogenation that was found to work well in RvD5
synthesis.
Chapter 5 discusses benzolipoxins, their importance in search for anti-inflammatory
therapeutics, and first total synthesis of thiolipoxin that has thiophene group in its core.

15

Chapter 1

1.1 Introduction
Inflammation plays an important role in the inflammatory processes that contribute to the
development of a range of widespread diseases such as cancer, cardiovascular disease, brain-
related disorders such as Alzheimer and multiple sclerosis
1
. The involvement of inflammation in
all of these conditions makes the investigation of the inflammatory processes and the elucidation
of the driving factors of it critical for the development of new drugs and therapeutics. Inflammation
plays an important role for mounting a defensive response upon incurring damage to cells. There
are two paths for the further development of these events: either inflammatory processes are
resolved or they persist resulting in a chronic condition. The first one is desirable for the healthy
outcome of the affected tissue, however, second may lead to the development of chronic conditions
when much more damage is done by inflammation itself. Thus, there is a need for investigations
of the possible ways for curbing the excessive inflammation and preventing further undesirable
damage.

16

There are two biosynthetic pathways that are involved in the initial inflammatory response
and further resolution of inflammation.
2
One that involves a pro-inflammatory role is the
arachidonic acid pathway which is shown in a simplified form on the left of Figure 1.1
2
. Another
that is shown on the right, is the omega-3 pathway that has more anti-inflammatory and pro-
resolution effects.

Scheme 1.1. Simplified scheme of biochemical pathways involved in the inflammatory
response and resolution
Prostaglandin H2 (PGH2) and leukotriene A4 (LTA4) are formed by cyclooxygenase – 2
(COX-2) and 5-lipoxygenase (5-LO) respectively. The compounds exert their actions through
GPCR binding and triggering further pro-inflammatory cascades inside cells. The reduction of
PGH2 formation that can be achieved by inhibition of COX-2 enzyme is a well known mechanism
by which non-steroidal anti-inflammatory drugs have their pain relieving effects
3
. Although LTA4
is known to produce LTC4 and LTB4 that contribute to the development of acute inflammation, it
also forms lipoxin A4 (LXA4) that has powerful anti-inflammatory and pro-resolving actions.
LXA4 is quickly metabolized and has very little time while it can exert its anti-inflammatory
actions, and so a plenty of research has been done to obtain stabilized analogs, for example,
benzolipoxins
4
, and in trying to block or reduce LTA4 hydrolase that increases levels of LXA4
5
.

17

The omega-3 pathway that includes eicosapentaenoic acid (EPA) and docosahexaenoic
acid (DHA) is mainly involved in the resolution of inflammation. Many health benefits of omega-
3 fatty acids are attributed to their anti-inflammatory pro-resolving properties. Resolvins of E-
series are formed from EPA and have been shown to have powerful pro-resolving actions
6
. For
our discussion D-series resolvins are more relevant due to the total syntheses described in the
current dissertation work which are described further.
The first aspect is pro-inflammatory response that is represented mainly by prostaglandins
and leukotrienes (Figure 1.2).

Prostaglandin E2 (PGE2) Leukotriene B4 (LTB4)

Scheme 1.2. Examples of pro-inflammatory compounds prostaglandin E2 (PGE2) and
leukotriene B4 (LTB4).
The production of pro-inflammatory lipid mediators in tissues can be successfully reduced
by targeting COX1 and COX2 enzymes
7
, for example, ibuprophen action is presumably attributed
to the reduced production of prostaglandin H2 (PGH2), and other prostaglandins down the
biosynthetic pathway
3
.

18

Another approach is the induction of the omega-3 resolution pathway which has recently
been realized as a new approach that may possibly lead to the development of novel therapeutics.
2

First approach has a limited scope and often not effective in many cases, thus the emphasis in
research community has been recently shifting more towards investigation of the second approach.
There are three structurally different groups of pro-resolving lipid mediators: maresins, resolvins
and protectins.
8

Scheme 1.3. Three major groups of pro-resolving lipid mediators. Example molecules from
each group: RvD1, Mar1, PD1.
In the current dissertation the total synthesis of both aspirin-triggered endogenous resolvin
– AT-RvD2 8, RvD5 4, (7R, 8R)-epoxide 7, (16S, 17S)-epoxide 11 are discussed. Synthetic
schemes of the compounds were designed and implemented. Special focus was given to
improvement of the current methodologies of the synthesis of such fatty acid compounds and the
development of completely new methods. The compounds - RvD5 4, AT-RvD2 8 and (16S, 17S)-
epoxide 11 -were matched with endogenous compounds by Professor Charles N. Serhan using LC-
MS/MS and were shown to be identical to the ones produced endogenously in the living tissues
by comparing the synthesized ones to the separated from living tissue.
19

Chapter 2: Total Synthesis of Resolvins (RvD5 and ATRvD2)
2.1 Introduction
A simplified biosynthetic scheme of the formation of the resolvins
2
is presented on the
following Scheme 2.1.

Scheme 2.1. Simplified scheme of the biosynthetic formation of the resolvins.
20

Docosahexaenoic Acid (DHA) 1 is converted to 17S-HDHA 2 by a sequence of two
reactions: oxidation by lipoxygenase and then reduction of the resulting peroxide by peroxidase.
17S-HDHA 2 is then oxidized by 5-lipoxygenase (5-LO) and then reduced by peroxidase to yield
resolvin D5 (RvD5) the total synthesis of which is presented in the current dissertation work.
Resolvins D3, D4 and D6 are also formed through 17S-HDHA 2. Intermediate compound 3 is then
converted to 7S, 8S-Epoxide 5, which is further converted to RvD1 and RvD2 by the hydrolase
enzyme.
Neutrophils (PMN) are the first immune cells that arrive in the area of inflammation and
have important innate immunity functions, particularly, pathogen destruction.
9
Excessive
accumulation of PMNs can lead to tissue damage and longer period for the inflammatory
condition
8
. RvD1 and AT-RvD1 have been shown to stop PMN transendothelial migration, and so
significantly reduce PMN infiltration with the potency similar to indomethacin. The effects are
thought to be achieved through acting on PMN GPCRs and lipoxin receptor
10
.
Stereochemical configuration of the lipid mediators have been shown to be crucial for their
biological activity.
10
Mediators can become less active, completely inactive or even reverse its
biological activity upon switch to its stereoisomer. Often a stereoisomer can retain its biological
activity at the same time having longer lifetime being a worse target for the mediators’ deactivation
pathways. For instance, both RvD1 and AT-RvD1 significantly reduce PMN transmigration,
however, AT-RvD1 is resistant towards one of the possible deactivation pathways for RvD1 by
eicosanoid oxidoreductases (EORs). Another even more distinct example is the development of
stable lipoxins, e.g. benzolipoxins
4
, that are resistant towards fast deactivation pathways of the
endogenous lipoxins. Then, endogenously produced lipid mediators can be isolated in nanomolar
quantities which is not enough for doing NMR experiments and figuring out the complete
stereochemistry of the compounds. Thus, total synthesis of the lipid mediators is crucial from two
reasons: elucidation of the complete stereochemistry of the endogenously produced compounds
by comparing them with the obtained by total synthesis and further biological investigations that
are not possible with the tiny amounts of lipid mediators separated from living tissues.
RvD2 was shown to be effective in murine models of microbial peritonitis also reducing
PMN infiltration similar to RvD1 and AT-RvD1. Moreover, the effect of RvD2 on human
leukocytes adhesion was demonstrated and was shown to occur largely through enhancing of
21

endothelial nitric oxide synthase (eNOS) NO-generation, vascular relaxant effects of which are
well established
11
. RvD2 was also shown to be effective in murine sepsis (peritonitis) models
reducing cytokine (IL-17, IL-10) levels that are known to affect sepsis survival rates and enhancing
bacterial clearance from the bloodstream. Sepsis currently represents a hard to treat condition with
low survival rates
12
. One of the issues with treating sepsis is that immune system needs to be
suppressed with drugs (to reduce levels of cytokines) that are currently used for the purpose but at
the same time harmful bacteria needs to be cleared out from the bloodstream. Thus RvD2
potentially represents a landmark in search for novel therapeutics that avoid the
immunosuppression which is extremely important in treating sepsis.
With similar reasoning as presented above, the investigation of Aspirin-triggered RvD2
(AT-RvD2) biological activity - stereoisomer of RvD2 differs from RvD2 by the configuration of
its hydroxyl group at 17
th
carbon - can be of great importance for the development of novel
therapeutics (Figure 4 below). AT-RvD2 is supposed to be formed through COX-2/Aspirin or
P450 pathway, via 17R-HDHA that is similarly converted to AT-RvD2 as presented on Figure 3
above.

Scheme 2.2. Structure of AT-RvD2, total synthesis of which is accomplished in the current
dissertation work

22

2.2 Results
2.2.1 Retrosynthetic Analysis of RvD5
For the synthesis of RvD5 methyl ester we decided to include 2 key steps: cis-selective
triple bond hydrogenation of 2.20 and copper-catalyzed coupling of the terminal alkyne 2.11 with
the bromide 2.19 (Scheme 2.3).

Scheme 2.3. Retrosynthetic scheme of RvD5 methyl ester 2.25

Compounds 2.8 and 2.13 in turn can be split further apart into simple and cheap starting materials.
Stereochemical configuration of the double bonds was established by using Lindlar
13
and Wittig
reactions
14
. The (S,S)- configuration of the hydroxyls was established by the usage of
enantiomerically pure (R)- glycidol as a starting material.
23

2.2.2 Synthesis of Building Blocks of RvD5
The synthesis of key intermediate 2.11 is presented on Scheme 2.4. (R)-Glycidol was
protected as TBS – ether and introduced to the ring opening reaction with 4-pentynoic methyl ester
2.4.

Scheme 2.4. Synthesis of key intermediate 2.11. (a) TBSCl, DMAP, imidazole, DCM, 98%; (b)
MeOH, 0.1eq H2SO4, reflux 98%; (c) NaHMDS, BF3∙Et2O, THF -78 ͦ C, 4h, 41% (d) TBDPSCl,
DMAP, imidazole, DCM, 87%; (e) CSA, MeOH/DCM, 92%; (f) H2/Lindlar cat., quinoline,
EtOAc, then DMP, Py, DCM, 94%; (g) Ph3PCHCHO, DCM, 30 °C, 24h, 89%; (h) CBr4, PPh3,
DCM, 95%; (i) LDA, THF, 4Å MS, -78 °C, 92%.

24

The previously utilized synthetic approach to the ester 2.5
15
, used in the synthesis of RvD2
is presented on Scheme 2.5. It involved: 2 steps protection of 4-pentynoic acid as orthoester which
was introduced to epoxide opening reaction with TBS-protected glycidol upon treatment with
BuLi and BF3∙Et2O, then 2 steps deprotection and treatment of the resulting acid with
diazomethane.

Scheme 2.5. Previously utilized approach for the synthesis of compound 2.5. (a) DCC, DMAP,
DCM, rt, overnight, 75%; (b) BF3·OEt2, DCM, Et3N, rt, 1h, 78%; (c) n-BuLi, BF3· OEt2, THF, -
78 ⁰C for 15min, then 2.2, 3h; (d) 1N HCl, THF-H2O (1:1), 0 ⁰C, 1h, 81% in two steps; (e) 1M
LiOH, THF-H2O (1:1), rt, 3h; (f) CH2N2, Et2O, 1h, 87% in two steps

25

Due to the emerging interest in protective groups-free reactions we tried to realize more
direct approach towards the epoxide opening reaction. Thus TBS-protected (R)-glycidol 2.2 was
introduced into the reaction with 4-pentynoic methyl ester 2.4 under different reaction conditions
shown on Scheme 2.6.

Scheme 2.6. Searching for optimal conditions of the direct synthesis of 2.5
It was discovered that the reaction works with 17% yield adding NaHMDS to vigorously
stirring mixture of 2.2 and 2.4 in THF as a base at -78 ⁰C and then after 30min BF3∙Et2O (entry
#1). At room temperature, right after the addition of NaHMDS immediate polymerization of the
reaction mixture occurred with no product observed (entry #2). The ratios of 2.2 to 2.4 and
NaHMDS to BF3 ∙ Et2O were varied (entries #3-6). Increasing the amount of NaHMDS to 1.1eq
increased the yield to 22%, however, further increase of NaHMDS did not significantly affected
the reaction (entries #3 and #4). Addition of larger amounts of BF3 ∙ Et2O reagent lowered the
yield (entry #5). Increasing the ratio of compound 2.2 to 2.4 to 1.4:1 resulted in almost 10% yield
improvement (entry#6), however, higher ratios of 2.2:2.4 did not improve the yield further
(entry#7). Simultaneous addition of NaHMDS and BF3 ∙ Et2O proved to be beneficial (entry #8).
#
2.2,
eq
2.4, eq Time, h Temp, ͦ C
NaHMDS,
equiv.
BF 3∙Et 2O,
Equiv. Yield, %
1
0.9 1.0 2 -78
0.9 1.0
17
2
0.9 1.0 2 r.t.
0.9 1.0
0
3
0.9 1.0 2 -78
1.1 1.0
22
4
0.9 1.0 2 -78
1.4 1.0
20
5
0.9 1.0 2 -78
1.1 1.3
17
6
1.4 1.0 2 -78
1.1 1.0
31
7
2.0 1.0 2 -78
1.1 1.0
30
8
1.4 1.0 2 -78
1.1 1.0
36
9
1.4 1.0 4 -78
1.1 1.0
41

10
1.4 1.0 8 -78
1.1 1.0
35

26

The yield was further improved by increasing the reaction time to 4h (entry #9), however, longer
reaction times lowered the yield (entry #10).
Different bases such as BuLi, KHMDS, LiHMDS, LDA were also implemented under the
conditions of entry #9 (Scheme 2.6), however, none of them gave any product at all. Changing of
the 4-pentynoic methyl ester to isopropyl ester did not result in any yield improvement. The
reaction was also run in DMF at room temperature using 2 equivalents of different bases such as
K2CO3, Et3N, LDA and 2 equivalents of CuI as a Lewis acid but none of the reactions worked.
It should be noted that the epoxide opening reaction under basic conditions that usually
utilizes BuLi requires the protection of sensitive groups. To the best of our knowledge the epoxide
opening described here is the first known example of intermolecular epoxide opening reaction that
tolerates the presence of such a sensitive group as non-conjugated methyl ester. The approach
allowed for 5 steps reduction of the synthetic route to 2.11 and improved the overall yield. Beside
the major improvement in the epoxide opening procedure we were also able to introduce a new
methodology for convertion of 2.7 to 2.8 which involved Lindlar hydrogenation
13
and Dess-Martin
oxidation
17
with wet DCM and pyridine. The two steps were successfully squeezed into just one
without any purification in-between which gave perfect yields (Scheme 2.4). The improvement
made can turn out to be of great importance since multiple reported syntheses of the compounds
with similar backbones utilized both reactions in succession
18
. Using less purification steps is
important for possible future industrial large-scale syntheses of the compounds
Aldehyde 2.8 was then reacted with (triphenylphosphoranylidene)acetaldehyde, so the
trans-double bond configuration was established
14
. Corey-Fuchs two-step procedure
19
yielded the
key intermediate 2.11 with excellent yield. It should be noted that LDA-treatment – 2
nd
step of
Corey-Fuchs – gave us only low-to-moderate yields without molecular sieves. So, the importance
of 4Å molecular sieves in this transformation should be emphasized.

27

The synthesis of intermediate 2.19 started with epoxide 2.2 opening under basic conditions
with 1-butyne 2.12 (Scheme 2.7).

Scheme 2.7. Synthesis of key intermediate 2.19. (a) BuLi, BF3∙Et2O, THF -78 ͦ C, 4h, 61% (b)
TBDPSCl, DMAP, imidazole, DCM, 90%; (c) CSA, MeOH/DCM, 87%; (d) H2/Lindlar cat.,
quinoline, EtOAc, then DMP, Py, DCM, 94%; (e) CHI3, CrCl2, THF, 51% (f) 5mol%Pd(OAc)2,
10mol%PPh3, propargyl alcohol, BuNH2, overnight, 89%. (g) NBS, PPh3, DCM, 93%.

The secondary alcohol group was protected as a TBDPS-silyl ether and TBS group was
selectively removed by camphorsulfonic acid (CSA) - treatment. Alcohol 2.15 was then converted
to 2.16 by the same procedure as in case of intermediate 2.11 synthesis. Takai reaction
20
of
aldehyde 2.16 furnished trans-vinyliodide 2.17.

28

The previously used approach for Sonogashira reaction of 2.17 required sequence of
TBDPS - group deprotection, TBS – protection (Scheme 2.8).

Scheme 2.8. Previously used approach towards Sonogashira reaction with compound 2.17.
(a) TBAF, THF, 65%; (b) TBSCl, Imidazole, DCM, 95%; (c) CuI, Pd(PPh3)4, NEt3, C6H6, 90%

The direct reaction of TBDPS-protected compound 2.17 failed to work under the standard
Sonogashira reaction conditions, thus the need for a new deprotection-protection sequence. We
decided to search literature for better reaction conditions and found that copper-free Sonogashira
reaction
21
of 2.17 with propargyl alcohol went perfectly with better yield and without the need of
deprotection-protection sequence (Scheme 2.9)

Scheme 2.9. Superior copper-free Sonogashira reaction

Moreover, the conditions proved to be useful for a number of our syntheses with
compounds that have rather complex scaffolds. Traditional Sonogashira reaction require very
careful handling and can easily fail if a small mistake is done during its set up. Developed by
french researchers
21
, the copper-free Sonogashira reaction turned out to be superior to the regularly
29

utilized Sonogashira conditions in our lab. The procedure is extremely easy, does not require much
of the precautions of the regular reaction, and reliably gives high-yields without observance of any
homocoupled products. The catalyst is generated in situ from Pd(OAc)2 and PPh3 which has an
additional advantage over traditionally used Pd(PPh3)4 catalyst due to the air/moisture/light
instability of the latter.
Subsequent NBS-treatment yielded bromide 2.19. Key intermediates 2.11 and 2.19 were
coupled together by copper-catalyzed reaction in DMF leading to the compound 2.20 (Scheme
2.10).

Scheme 2.10. Synthesis of 2.20 and attempts for the deprotection

Then we tried to deprotect compound 2.20 since our plan was to try to hydrogenate the
deprotected intermediate using the known Boland procedure
22
which does not work with sterically
hindered compounds. For the deprotection we used TBAF or TASF reagents under room
temperature both of which failed to work leading to the darkening of the reaction mixture and
complete destruction of the starting material. Lowering the temperature to 0 °C and stirring for
prolonged times was not successful.

30

Ultimately we decided to perform copper-catalyzed reaction on the deprotected 2.11 and
2.19. Since we had only 2-step precursors – 2.10 and 2.18 we tried to accomplish the 2.10 to 2.21
and 2.18 to 2.22 transformations without a column chromatography in-between for the sake of
saving some time, which worked very-well (Scheme 2.11).

Scheme 2.11. Synthesis of 2.21 and 2.22

Coupling of the unprotected compounds 2.21 and 2.22 successfully generated the
deprotected compound 2.23 although the yield was much lower. Further Boland reduction failed
to work (Scheme 2.12).

Scheme 2.12. Synthesis of 2.23 and failed Boland the reduction

Giving the fact that we were unable to reduce the deprotected compound 2.23 by the known
Boland procedure we sought for alternative approaches. First we decided to use simple Lindlar
reduction of the protected piece 2.20 (Scheme 2.13). Multiple products were formed during the
reaction which was clearly indicated by TLC staining, however, we were able to isolate some of
31

the desired compound 2.24 with low yield. Compound 2.24 was further deprotected giving the
final RvD5 methyl ester 2.25.

Scheme 2.13. Synthesis of the final RvD5 methyl ester

Since the yield of the hydrogenation step was low we screened different conditions for the
reaction. Change of solvent from EtOAc to hexanes did not change the yield. Lowering the
temperature to 0 °C did not affect the outcome of the reaction. Searching through a review which
summarized the known hydrogenation procedures of fatty-chain compounds
23
we came across
special conditions for Lindlar hydrogenation
24
that worked on a triple bond in a γ-position relative
to TBDPS-protected alcohol group (Scheme 2.14):

Scheme 2.14. The modified Lindlar reaction, the conditions of which we successfully
applied to our synthesis

32

The reaction was done in a solvent mixture: EtOAc:pyridine:1-octene = 10:1:1 for 6 hours
which yielded the product with 95% yield. These conditions were successfully applied to our
molecule giving 2.24 with good yield of 62%, although the reaction times are much longer: 3-4
days instead of just 6 hours which can possibly be explained by sterical hindrance of two TBDPS-
groups (Scheme 2.15).

Scheme 2.15. Improved Lindlar conditions applied for the hydrogenation of compound 2.20.

This presents the second known example of the application of such Lindlar conditions to
the more complex substrate with 2 bonds hydrogenated at the same time. The reaction was then
successfully applied for a number of compounds in our lab
25
.

33

2.2.3 Retrosynthetic Analysis of AT RvD2
To synthesize AT RvD2 methyl ester 2.43 we first envisioned triple-bond hydrogenation
of 2.42 which can be retrosynthetically split apart into two smaller precursors 2.40 and 2.33 that
can be coupled to obtain 2.42 using Sonogashira reaction
26
(Scheme 2.16).

Scheme 2.16. Retrosynthetic scheme of AT RvD2 methyl ester 2.43

The stereochemical configuration of the hydroxyl group present in 2.40 is defined by the
use of enantiomerically pure (R)-glycidol as a starting material. The double bond in 2.40 is
generated by the Lindlar hydrogenation
13
. Two trans-double bonds in 2.33 can be generated by
the Wittig chain elongation
28
reaction with (triphenylphosphoranylidene)acetaldehyde; two other
stereocenters can be obtained by the Sharpless asymmetric dihydroxylation
16
.
34

2.2.4 Synthesis of Building Blocks of AT RvD2
The epoxide opening reaction under basic conditions that usually utilizes BuLi requires the
protection of sensitive groups, in our case methyl ester. We optimized the conditions for epoxide
opening reaction that does not require any protection of the methyl ester functionality. To the best
of our knowledge the reaction is the first known example of intermolecular epoxide opening
reaction that tolerates the presence of such a sensitive group as non-conjugated methyl ester. The
approach allowed for 5 steps reduction of the synthetic route to 2.40 and improved the overall
yield. Beside the major improvement in the epoxide opening procedure we were also able to
introduce a new methodology for convertion of 2.37 to 2.39 which involved Lindlar
hydrogenation
13
and Dess-Martin oxidation
17
with wet DCM and pyridine. The two steps were
successfully combined into just one without any purification in-between which gave high yields
(Scheme 2.17). The improvement made turn out to be of great importance since multiple reported
syntheses of the compounds with similar backbones utilize both reactions in succession.
23
Using
less purification steps is important for possible future industrial large-scale syntheses of these
compounds.

Scheme 2.17. Improved synthetic route to the vinyl iodide 2.40. (a) TBSCl, DMAP, imidazole,
DCM, 98%; (b) MeOH, 0.1eq H2SO4, reflux 98%; (c) NaHMDS, BF3∙Et2O, THF -78 ͦ C, 4h, 41%
(d) TBDPSCl, DMAP, imidazole, DCM, 87%; (e) CSA, MeOH/DCM, 92%; (f) H2/Lindlar cat.,
quinoline, EtOAc, then DMP, Py, DCM, 94%; (g) CHI3, CrCl2, THF, 45%.

35

The synthetic scheme for the synthesis of compound 2.33 is shown below on Scheme 2.18.

Scheme 2.18. Synthetic scheme of the key intermediate 2.33.

The synthesis of the key intermediate 2.33 starts from copper-catalyzed coupling between
propargyl alcohol and 1-bromo-2-pentyne furnishing compound 2.26. Addition of MS4Ǻ to the
reaction improved the yield by about 10%. Compound 2.26 was then reduced with lithium
aluminum hydride to the trans-alcohol 2.27 which was dihydroxylated by the Sharpless
asymmetric reaction with AD-mix-β establishing the stereochemical configuration of the two
adjacent hydroxyls. Silyl protection of 2.28 and subsequent Py∙HF - catalyzed selective
deprotection
29
of the primary hydroxyl yielded 2.40.

36

For the deprotection of the primary hydroxyl group the Py∙HF reagent proved to be superior
to the more often used CSA reagent. CSA usage for the reaction stably gave low yields due to
deprotection of secondary alcohol groups (Scheme 2.19).

Scheme 2.19. Previously used CSA deprotection of the primary alcohol group

These side reactions can be completely avoided by using the much milder Py∙HF reagent.
One-step sequence of the Lindlar hydrogenation-Dess-Martin oxidation was also utilized here
giving 2.31. Wittig chain elongation of 2.31 with (triphenylphosphoranylidene)acetaldehyde
turned out to give a mixture of products which we were not able to separate. So the first step of
Corey-Fuchs procedure
19
was done and the products were successfully isolated due to larger
differences in Rf than their corresponding aldehydes furnishing pure compound 2.32. This
regularly utilized procedure for the convertion of vinyldibromides into their corresponding alkynes
using LDA treatment in THF under -78 ⁰C gave only low-to-moderate yields. Addition of MS4Ǻ
molecular sieves dramatically increased the yield up to 91% yielding the desired intermediate 2.33.

37

The final steps of the synthesis are shown on the Scheme 2.20 below.

Scheme 2.20. The completion of the AT RvD2 methyl ester synthesis.

Typical Sonogashira reaction conditions
26
require very strict conditions which include
freeze-thaw technique to deoxygenate the reaction mixture, and very careful handling in order to
avoid any oxygen contamination. The catalyst that is generally used - Pd(PPh3)4 – is light and air
sensitive, and goes bad upon prolonged storage and rather expensive. Sometimes it can be
extremely hard to abide by all the rules imposed by the classic Sonogashira reaction and substantial
amount of homo-coupled products are observed dramatically reducing the yield of the reaction.
We were fascinated by the possibility of doing the Sonogashira reaction upon copper-free
conditions which could simplify the procedure and make it more reliable. In the literature we found
a copper-free procedure of the Sonogashira reaction that utilizes Pd(OAc) 2/PPh3 and n-
buthylamine as a solvent which was firstly described by French authors in 1993
21
but has largely
been ignored. In multiple cases in our lab the procedure turned out to be way superior to the classic
one. It does not require careful handling of the catalyst since both Pd(OAc)2 and PPh3 are stable
upon air and light exposure, the reaction can be exposed to the air for short periods of time while
setting up the reaction without any drop in yields. Besides, Pd(OAc)2 is cheaper than Pd(PPh3)4.
The yields are much more reproducible and no homo-coupling is observed. It should also be noted
that typical Sonogashira reaction failed to give any yield with TBDPS-group in 2.40, which
required additional deprotection-reprotection with TBS-group as is described in the 2.2.2 –section
for RvD5 synthesis of the present work. TBS-protected compound gave only moderate yields with
the classic procedure which further shows the superiority of the procedure that French researchers
described before. TBAF-deprotection
31
and Zn/Cu/Ag – Boland reduction
22
ultimately yielded
compound 2.43. Boland procedure gave us only 30% yield, so we searched for alternative synthetic
38

approaches to accomplish the reduction. Two different Lindlar hydrogenation procedures for the
hydrogenation of 2.42 and its deprotected analog were utilized with EtOAc/Quinoline and
EtOAc/1-octene/pyridine = 10:1:1
23
as solvents. None of them proved to have better yield over the
standard procedure.

2.3 Conclusion
The total synthesis of RvD5 methyl ester 2.25 was accomplished in 19 steps in an overall
yield of 6%. An entirely new epoxide opening reaction was developed and optimized. The standard
synthetic procedures, such as Corey-Fuchs, Sonogashira and others that have been used in our lab
for the syntheses of similar structure compounds were improved by either changing conditions or
switching completely to a different variation of the reaction. Very mild Lindlar hydrogenation
conditions were found in the literature and successfully applied for the first time for more complex
fatty acid compounds. The procedure then proved useful for the hydrogenation of other even more
complex fatty compounds in our lab.
The total synthesis of AT-RvD2 2.43 was realized in 20 steps with overall yield of 1.7%.
The selective deprotection Py·HF procedure was introduced which allowed for yield improvement
and better selectivity of primary alcohol group deprotection. The copper-free Sonogashira reaction
again proved to be superior to the traditionally used one allowing us to accomplish one of the key
steps of the synthetic route.

39

2.4 Experimental Procedures
All reactions, unless otherwise noted, were carried in flame dried flasks under argon
atmosphere. Dried and concentrated refers to removal of residual water with anhydrous MgSO4,
followed by evaporation of the solvent on the rotary evaporator. THF was freshly distilled from
sodium-benzophenone, benzene and dichloromethane from CaH2 and anhydrous DMF, EtOH, and
MeOH were purchased from commercial sources.
1
H and
13
C NMR spectra were recorded on a
Varian Mercury 400 or 600 MHz using residual
1
H or
13
C signals of deuterated solvents as internal
standards. UV spectra were recorded on a Hewlett-Packard 8350 instrument. HPLC analyses were
performed on a Rainin dual pump HPLC system equipped with a Phenomenex ODS column and
an UV-VIS detector.

2.4
Methyl pent-4-ynoate (2.4): 5.0g (51mmol) of pent-4-ynoic acid was dissolved in 100ml
of methanol, 0.5ml of concentrated sulfuric acid was added and the mixture was refluxed
overnight. Methanol was removed and the mixture was purified on a silica column with 10%
Ether/pentanes furnishing 5.5g (96%) of the pure ester 2.4.
1
H NMR (400MHz, CDCl3) 3.70 (s,
3H), 2.58 - 2.53 (m, 2H), 2.53 - 2.46 (m, 2H), 1.97 (t, J = 2.6 Hz, 1H).

2.2
(S)-(tert-Butyldimethylsilyl) glycidol (2.2): 100ml flask was flame-dried and filled with
argon gas. In the flask mixture of 2.4g (16mmol) of t-buthyldimethylsilylchloride, 1.1g (16mmol)
imidazole and 0.1g (0.8mmol) of dimethylaminopyridine was dissolved in 20ml of
dichloromethane and 1.0g (14mmol) of (R)-glycidol was cannulated under argon. The mixture was
stirred overnight, worked up with saturated ammonium chloride, extracted with diethyl ether
(3x30ml) and the solvent was removed. After purification on a silica column with 10%
40

Et2O/pentanes 2.5g (13mmol, 98%) of 2.2 was obtained.
1
H NMR (400MHz, CDCl3) 3.85 (dd, J
= 11.9, 3.2 Hz, 1H), 3.66 (dd, J = 11.9, 4.7 Hz, 1H), 3.08 (dddd, J = 4.6, 3.9, 3.2, 2.7 Hz, 1H), 2.77
(dd, J = 5.2, 4.0 Hz, 1H), 2.64 (dd, J = 5.1, 2.7 Hz, 1H), 0.90 (s, 5H), 0.08 (s, 3H), 0.07 (s, 2H).

2.5
(S)-Methyl 8-((tert-butyldimethylsilyl)oxy)-7-hydroxyoct-4-ynoate (2.5): 100ml flask
was flame-dried and filled with argon gas. In the flask a mixture of 0.54g (4.8mmol) of 2.4 and
1.27g (6.7mmol) of 2.2 were dissolved in 5ml of THF under -78 ⁰C and 0.67ml (5.3mmol) of
BF3·OEt2 and 5.3ml (5.3mmol) of 1M NaHMDS solution were added at the same time dropwise
within 2min under argon. The mixture was stirred for 3.5h at -78 ⁰C and quenched with saturated
ammonium chloride solution. The mixture was extracted with dichloromethane (3x30ml), dried
over sodium sulfate, solvent removed and the remaining fraction was purified on a silica column
with 12% EtOAc/hexanes yielding 0.6g (2.0mmol, 41%) of 2.5.
1
H NMR (400MHz, CDCl3) 3.78-
3.56 (m, 6H), 2.55 - 2.45 (m, 4H), 2.39 - 2.35 (m, 2H), 0.90 (s, 9H), 0.08 (s, 6H).

2.6
(S)-Methyl 8-((tert-butyldimethylsilyl)oxy)-7-((tert-butyldiphenylsilyl)oxy)oct-4-
ynoate (2.6): To flame-dried 100ml round-bottom flask 0.55g (1.8mmol) of 2.5, 0.15g (2.2mmol)
of imidazole, 0.05g(0.4mmol) dimethylaminopyridine were added under argon and dissolved in
20ml of dichloromethane, and 0.57ml (2.2mmol) of tertbuthyldiphenylsilylchloride was added to
the reaction mixture. After 15h the mixture was worked up with saturated ammonium chloride
solution, extracted with dichloromethane, dried down on the rotary evaporator and purified on a
silica column with 5% EtOAc/hexanes solvent yielding 0.86g (1.6mmol, 87%) of 2.6.
1
H NMR
(400MHz, CDCl3) 7.74 7.65 (m, 4H), 7.46 - 7.32 (m, 6H), 3.80 (p, J = 5.4 Hz, 1H), 3.67 (s, 3H),
41

3.53 (dd, J = 5.4, 1.0 Hz, 2H), 2.43 (dddd, J = 10.2, 9.3, 6.9, 4.6 Hz, 4H), 2.35 (dt, J = 5.8, 2.1 Hz,
1H), 2.28 (dt, J = 5.4, 2.2 Hz, 1H), 1.06 (s, 9H), 0.83 (s, 9H), -0.04 (s, 3H), -0.07 (s, 3H).

2.7
(S)-Methyl 7-((tert-butyldiphenylsilyl)oxy)-8-hydroxyoct-4-ynoate (2.7): 0.86g
(1.6mmol) of compound 2.6 was dissolved in 26ml of dichoromethane mixed with 26ml of
methanol and 0.18g (0.8mmol) of camphorsulfonic acid was added upon vigorous stirring. The
reaction was monitored by TLC every 15min. After 1h TLC showed that the reaction was
completed and it was quenched with 0.45ml (3.2mmol) of triethylamine. The solvent was removed
and the mixture was purified on a silica column with 12% EtOAc/hexanes solvent which yielded
0.62g (1.5mmol, 92%) of 2.7.
1
H NMR (400MHz, CDCl3) 7.70 - 7.62 (m, 4H), 7.47 - 7.33 (m,
6H), 3.76 (dtd, J = 7.1, 5.2, 3.5 Hz, 1H), 3.65 (s, 3H), 3.50 (qd, J = 11.9, 4.6 Hz, 2H), 2.25 2.17
(m, 2H), 2.17 (d, J = 0.4 Hz, 1H), 1.56 1.35 (m, 4H), 1.07 (s, 3H).
13
C NMR (400MHz, CDCl3)
136.04, 135.85, 129.96, 127.91, 127.80, 77.36, 74.14, 66.13, 34.09, 33.49, 29.18, 27.23, 24.87.

2.8
(S,Z)-Methyl 7-((tert-butyldiphenylsilyl)oxy)-8-oxooct-4-enoate (2.8): 0.62g (1.5mmol)
of 2.7 was dissolved in 40ml of ethyl acetate and 0.1ml of quinoline and 20mg of Lindlar catalyst
were added. The reaction mixture was purged with hydrogen and carefully monitored by the TLC
(10%EtOAc/hexanes). After the reaction completion, the mixture was filtered out, solvent was
evaporated and the remaining oil was dissolved in 30ml of regular dichloromethane. 2ml of
pyridine and 0.68g (1.6mmol) of Dess-Martin periodinane were added under vigorous stirring at
room temperature. After 15min the reaction mixture was quenched with sodium bicarbonate-
42

sodium thiosulfate solution and extracted with 3x30ml dichloromethane. The organic layer was
separated and the solvent was removed. The remaining oily mixture was purified on a silica column
with 15% EtOAc/hexanes solvent giving 0.58g (94%) of the desired product.
1
H NMR (400MHz,
CDCl3) 9.56 (d, J = 1.6 Hz, 1H), 7.67 - 7.60 (m, 4H), 7.48 - 7.32 (m, 6H), 5.45 - 5.39 (m, 2H),
4.06 (ddd, J = 6.4, 5.6, 1.6 Hz, 1H), 3.65 (s, 3H), 2.46 (dt, J = 14.9, 5.9 Hz, 1H), 2.35 (dt, J = 16.1,
5.8 Hz, 1H), 2.31 2.21 (m, 4H), 1.11 (s, 9H).
13
C NMR (400MHz, CDCl3) 203.44, 173.53, 135.95,
135.94, 130.92, 130.22, 130.18, 127.98, 127.93, 124.56, 53.57, 51.70, 33.85, 31.74, 27.08, 22.81,
14.27.

2.9
Methyl (S,4Z,8E)-7-((tert-butyldiphenylsilyl)oxy)-10-oxodeca-4,8-dienoate (2.9): 10ml
flask was flame-dried and filled with argon gas. In the flask 0.18g (0.42mmol) of Aldehyde 2.8
and 0.16g (0.53mmol) (triphenylphosphoranylidene) acetaldehyde were dissolved in 5ml of
dichloromethane and refluxed for 20h under argon. After the TLC (10% EtOAc/Hexanes) showed
completion the reaction mixture was dried down on a rotary evaporator and the remaining fraction
was purified on column with 10%EtOAc/hexanes solvent yielding 0.17g (0.38mmol) of the
aldehyde 2.9.
1
H NMR (400MHz, CDCl3) 9.46 (d, J = 8.0 Hz, 1H), 7.71 - 7.55 (m, 4H), 7.47 -
7.32 (m, 6H), 6.70 (dd, J = 15.6, 4.9 Hz, 1H), 6.20 (ddd, J = 15.6, 8.0, 1.5 Hz, 1H), 5.44 - 5.25 (m,
2H), 4.52 - 4.43 (m, 1H), 3.64 (s, 3H), 2.39 - 2.20 (m, 4H), 2.13 (q, J = 7.1 Hz, 2H), 1.08 (s, 9H).

2.10
Methyl (S,4Z,8E)-11,11-dibromo-7-((tert-butyldiphenylsilyl)oxy)undeca-4,8,10-
trienoate (2.10): 100ml flask was flame-dried and filled with argon gas. In the flask, mixture
containing 0.65g (2.0mmol) of tetrabromomethane and 1.6g (2.9mmol) of triphenylphosphine was
dissolved in 10ml of anhydrous DCM at 0 ⁰C and stirred for 30min under argon. Then 0.17g
43

(0.4mmol) of 2.9 dissolved in 3ml of anhydrous dichloromethane was cannulated under argon.
The reaction was allowed to warm up to room temperature, stirred for 30 more minutes, worked
up with saturated sodium bicarbonate solution and extracted with dichloromethane (4x30ml). The
combined organic layer was dried over sodium sulfate, filtered out and the solvent was evaporated.
The remaining oily mixture was successfully purified with 3% EtOAc/hexanes as a solvent
furnishing 0.23g (0.4mmol, 98%) of the desired product 2.10.
1
H NMR (400MHz, CDCl3) 7.70 -
7.60 (m, 4H), 7.46 - 7.30 (m, 6H), 6.81 (d, J = 10.2 Hz, 1H), 6.09 (ddt, J = 15.3, 10.3, 1.3 Hz, 1H),
5.80 (dd, J = 15.3, 5.9 Hz, 1H), 5.40 - 5.29 (m, 2H), 4.22 (dddd, J = 7.5, 6.3, 5.0, 1.4 Hz, 1H), 3.65
(s, 3H), 2.31 - 2.17 (m, 4H), 2.18 - 2.12 (m, 2H), 1.08 (s, 6H).
13
C NMR (400MHz, CDCl3) 173.60,
139.66, 136.50, 136.07, 136.04, 134.11, 133.80, 130.00, 129.88, 129.84, 127.74, 127.69, 126.76,
125.89, 90.89, 73.17, 60.55, 51.68, 35.61, 33.99, 27.17, 23.00, 19.48, 14.36.

2.11
Methyl (S,4Z,8E)-7-((tert-butyldiphenylsilyl)oxy)undeca-4,8-dien-10-ynoate (2.11):
50ml flask was flame-dried and filled with argon gas. In the flask, 0.23g (0.37mmol) of 2.10 and
0.1g of molecular sieves 4Å were dissolved in 1ml of anhydrous THF. The reaction mixture was
cooled down to -78 ⁰C and 1.0ml (2.0mmol) of 2M solution of LDA was added. After stirring for
2h the reaction mixture was worked up with saturated ammonium chloride solution, extracted with
dichloromethane (4x30ml), solvent was removed and the remaining fraction was purified on a
silica column with 2% EtOAc/hexanes solvent furnishing 0.15g (0.34mmol, 92%) of the product
2.11.
1
H NMR (400MHz, CDCl3) 7.65 (ddt, J = 21.3, 6.7, 1.5 Hz, 4H), 7.47 - 7.31 (m, 6H), 6.19
(dd, J = 15.9, 5.5 Hz, 1H), 5.57 (ddd, J = 15.9, 2.2, 1.5 Hz, 1H), 5.40 5.24 (m, 2H), 4.23 (dtd, J =
7.1, 5.2, 1.5 Hz, 1H), 3.65 (s, 3H), 2.85 (d, J = 2.3 Hz, 1H), 2.30 1.98 (m, 6H), 1.07 (s, 9H).
13
C
NMR (400MHz, CDCl3) 173.58, 147.13, 136.01, 136.00, 135.99, 134.07, 133.60, 130.16, 129.92,
129.89, 129.88, 127.76, 127.76, 127.74, 127.72, 125.56, 108.61, 82.10, 77.68, 77.68, 72.93, 51.65,
35.43, 33.94, 27.15, 27.15, 22.94, 19.49.

44

2.21
Methyl (S,4Z,8E)-7-hydroxyundeca-4,8-dien-10-ynoate (2.21): The reaction was done
on 0.23g (0.4mmol) of 2.10. Following the procedure described for compound 2.11 the resulting
fraction (no purification was done) was dissolved in 3ml of THF and 0.8ml of 1M TBAF
(0.8mmol) was added. After stirring for 3h solvent was removed on rotary evaporator and the
remaining oil was purified on a silica gel column with 15% of EtOAc/hexanes yielding 0.14g
(83%) of 2.21.
1
H NMR (400MHz, CDCl3) 6.27 (dd, J = 16.0, 5.3 Hz, 1H), 5.76 (ddd, J = 16.0,
2.3, 1.7 Hz, 1H), 5.60 5.39 (m, 2H), 4.28 - 4.21 (m, 1H), 3.67 (s, 3H), 2.89 (dt, J = 2.3, 0.6 Hz,
1H), 2.45 - 2.31 (m, 7H).
13
C NMR (400MHz, CDCl3) 173.87, 147.00, 131.81, 125.78, 108.92,
78.02, 77.36, 71.21, 51.85, 35.06, 33.67, 22.86.

2.13
(S)-1-(tert-Butyldiphenylsilyloxy)hept-4-yn-2-ol (2.13): 100ml flask was flame-dried
and filled with argon gas. To the flask 1-butyne (286 mg, 5.3 mmol) in dry THF (10 mL) was
added and then 2.5M n-BuLi (2.12 mL, 5.3 mmol) solution was slowly added at -78 ⁰C under
argon. After 0.25 h BF3 · Et2O (0.64 mL, 5.3 mmol) was added drop wise at -78 ⁰C. To the reaction
mixture protected glycidol 2.2 (0.5 g, 2.65 mmol) was added and stirred for 3h at -78 ⁰C under
argon. The reaction mixture was warmed to room temperature, quenched with saturated aqueous
NH4Cl (15 mL) and extracted with Et2O (3 x 15 mL). The organic layer was dried with MgSO4,
filtered and the solvent removed in vacuo. The crude reaction mixture was purified on silica gel
using EtOAc-hexanes (4%) as the eluent to afford compound 2.13 (600 mg, 94%) as a clear
colorless oil.
1
H NMR (400 MHz, CDCl3) 3.77 3.72 (m, 1H), 3.70 (dd, J = 9.9, 4.2 Hz, 1H), 3.60
(dd, J = 9.8, 5.8 Hz, 1H), 2.46 (d, J = 4.8 Hz, 1H), 2.42 2.33 (m, 2H), 2.22 2.10 (m, 2H), 1.11 (t,
45

3H), 0.90 (s, 9H), 0.08 (s, 6H).
13
C NMR (400 MHz, CDCl3) 84.15, 75.21, 70.63, 65.81, 26.03,
23.55, 18.46, 14.33, 12.55, -5.23, -5.26.

2.14
(S)-1-(tert-Butyldiphenylsilyloxy)-2-(tert-butyldiphenylsilyloxy)hept-4-yne (2.14):
25ml flask was flame-dried and filled with argon gas. To the flask with imidazole (95 mg, 1.39
mmol) and DMAP (8 mg, 0.06 mmol) in 5ml of anhydrous DCM, TBDPS-Cl (0.36 mL, 1.39
mmol) was added dropwise at 0 ⁰C under argon. The alcohol 2.13 (280 mg, 1.15 mmol) was
cannulated to the flask and stirred overnight at room temperature. The reaction mixture was
quenched with saturated aqueous NH4Cl (7 mL) and extracted with Et2O (3 x 7 mL). The organic
layer was dried with MgSO4, filtered and the solvent removed in vacuo. The crude reaction mixture
was purified on silica gel using EtOAc- hexanes (1%) as the eluent to afford the protected diol
2.14 (525 mg, 9%) as a clear colorless oil.
1
H NMR (400 MHz, CDCl3) 7.85 7.65 (m, 4H), 7.55
7.29 (m, 6H), 3.83 (p, J = 5.5 Hz, 1H), 3.55 (dd, J = 5.4, 3.3 Hz, 2H), 2.44 2.34 (m, 1H), 2.32 -
2.23 (m, 1H), 2.12 (qt, J = 7.5, 2.4 Hz, 2H), 1.10 (t, 3H), 1.07 (s, 9H), 0.84 (s, 9H), -0.03 (s, 3H),
-0.06 (s, 3H).
13
C NMR (400 MHz, CDCl3) 136.10, 136.03, 134.47, 134.34, 129.69, 129.66,
127.62, 83.29, 76.47, 72.78, 65.80, 27.09, 26.05, 24.12, 19.54, 18.46, 14.34, 12.62, -5.34, -5.35.

2.15
(S)-2-(tert-Butyldiphenylsilyloxy)hept-4-yn-1-ol (2.15): 25ml flask was flame-dried and
filled with argon gas. In the flask, to a solution of protected diol 2.14 (0.5 g, 1.04 mmol) in 5ml of
anhydrous DCM camphor sulfonic acid (144 mg, 0.62 mmol) was added at room temperature
under argon and monitored for 1 h. The reaction was quenched with Et3N (0.09 mL, 0.62 mmol)
and the solvent was evaporated in vacuo without workup. The crude reaction mixture was purified
on silica gel using EtOAc-hexanes (1:10) as the eluent to afford alcohol 2.15 (370 mg, 97%) as a
46

clear colorless oil.
1
H NMR (400 MHz, CDCl3) 7.82 - 7.72 (m, 4H), 7.57 - 7.37 (m, 6H), 4.06 -
3.87 (m, 1H), 3.70 (d, J = 4.6 Hz, 2H), 2.47 (ddt, J = 16.4, 7.7, 2.5 Hz, 1H), 2.36 (ddt, J = 16.4,
4.9, 2.4 Hz, 1H), 2.18 - 2.06 (m, 3H), 1.16 (s, 9H), 1.10 (t, J = 7.5 Hz, 3H).
13
C NMR (400 MHz,
CDCl3) 135.86, 135.71, 133.64, 133.62, 129.89, 129.85, 127.80, 127.68, 83.83, 75.43, 72.62,
65.56, 27.01, 23.91, 19.33, 14.10, 12.41.

2.16
(S, Z)-2-((tert-Butyldiphenylsilyl)oxy)hept-4-enal (2.16): 2.75g (7.5mmol) of 2.15 was
dissolved in 80ml of ethyl acetate and 0.1ml of quinoline and 40mg of Lindlar catalyst were added.
The reaction mixture was purged with hydrogen and carefully monitored by the TLC
(10%EtOAc/hexanes). After the reaction completion, the mixture was filtered out, solvent was
evaporated and the remaining oil was dissolved in 100ml of regular dichloromethane, 2ml of
pyridine and 3.3g (7.8mmol) of Dess-Martin periodinane were added under vigorous stirring at
room temperature. After 15min the reaction mixture was quenched with sodium bicarbonate-
sodium thiosulfate solution and extracted with 3x30ml dichloromethane. The organic layer was
separated and the solvent was removed. The remaining oily mixture was purified on a silica column
with 15% EtOAc/hexanes solvent giving 2.58g (94%) of the desired product.
1
H NMR (400 MHz,
CDCl3) 9.57 (d, J = 1.7 Hz, 2H), 7.71 - 7.61 (m, 4H), 7.49 - 7.33 (m, 6H), 5.52 - 5.41 (m, 1H),
5.40-5.27 (m, 1H), 4.06 (td, J = 6.5, 1.7 Hz, 1H), 2.44 (dt, J = 14.1, 6.7 Hz, 1H), 2.34 (dt, J = 13.9,
6.5 Hz, 1H), 1.99 1.87 (m, 2H), 1.12 (s, 9H), 0.90 (t, J = 7.5 Hz, 3H).
13
C NMR (400 MHz, CDCl3)
203.52, 135.95, 135.95, 135.11, 133.24, 133.12, 130.18, 130.13, 127.95, 127.89, 122.17, 77.94,
31.15, 27.08, 20.74, 19.49, 14.14.

2.17
(S, E, Z)-3-((tert-Butyldiphenylsilyl)oxy)-1-iodoocta-1,5-diene (2.17): 100ml flask was
flame-dried and filled with argon gas. To the flask, 9.3g (75.7mmol) of chromium(II) chloride was
47

added and then mixed with 30ml of anhydrous THF, and cooled down to 0 ⁰C. Then, 11.2g
(28.5mmol) of iodoform with 3.5g (9.5mmol) of 2.16 dissolved in 10ml of anhydrous THF were
cannulated to the reaction mixture and stirred at 0 ⁰C for 4h. Then it was worked up with 400ml
of saturated ammonium chloride solution and extracted with 3x80ml of dichloromethane. Solvent
was removed and the mixture was purified on a silica column with pure hexanes 2.3g (51%) of
2.17.
1
H NMR (400 MHz, CDCl3) 7.76 - 7.54 (m, 4H), 7.51 - 7.32 (m, 6H), 6.49 (dd, J = 14.4, 6.5
Hz, 1H), 5.98 (dd, J = 14.4, 1.1 Hz, 1H), 5.49 - 5.32 (m, 1H), 5.32 - 5.13 (m, 1H), 4.17 - 3.98 (m,
1H), 2.32 - 2.07 (m, 2H), 1.84 (dtd, J = 9.2, 7.4, 5.6 Hz, 2H), 1.07 (s, 9H), 0.87 (t, J = 7.5 Hz, 3H).
13
C NMR (400 MHz, CDCl3) 148.04, 136.03, 136.01, 134.54, 133.97, 133.65 129.90, 129.87,
127.74, 127.72, 123.18, 76.88, 75.93, 35.31, 27.14, 20.75, 19.48, 14.33.

2.18
(S,4E,8Z)-6-((tert-Butyldiphenylsilyl)oxy)undeca-4,8-dien-2-yn-1-ol (2.18): 10ml flask
was flame-dried and filled with argon gas. In the flask 0.53g (1.1mmol) of the vinyl iodide 2.17
was dissolved in 3ml of n-buthylamine and 0.012g (0.05mmol) of Pd(OAc)2 with 0.03g (0.1mmol)
of PPh3 were added. The reaction mixture was stirred for 15min under argon, and 0.02g
(0.05mmol) of alkyne 2.8 was added in 2ml of nbuthylamine. After stirring for overnight at room
temperature under argon, the solvent was removed on a rotary evaporator and the mixture was
purified on a silica column with 5% EtOAc/hexanes furnishing 0.40g (89%) of the compound 2.18.
1
H NMR (600MHz, CDCl3) 7.72 - 7.56 (m, 4H), 7.47 - 7.33 (m, 6H), 6.13 (dd, J = 15.9, 5.5 Hz,
1H), 5.63 (d, J = 17.4 Hz, 1H), 5.42 - 5.28 (m, 1H), 5.22 - 5.13 (m, 1H), 4.37 (d, J = 1.9 Hz, 2H),
4.21 (q, J = 5.5 Hz, 2H), 2.27-2.05 (m, 2H), 1.77 (dq, J = 14.1, 7.1 Hz, 2H), 0.83 (t, J = 7.6 Hz,
2H).
13
C NMR (600MHz, CDCl3) 146.11, 136.03, 136.01, 134.35, 134.17, 133.73, 129.87, 129.83,
127.72, 127.70, 127.68, 123.28, 108.74, 87.56, 84.29, 73.23, 51.83, 35.57, 27.16, 20.71, 19.51,
14.23.

48

2.19
(((S,4E,8Z)-1-Bromoundeca-4,8-dien-2-yn-6-yl)oxy)(tert-butyl)diphenylsilane (2.19):
25ml flask was flame-dried and filled with argon gas. In the flask, 0.35g (0.8mmol) of compound
2.18 was dissolved in 8 ml of anhydrous DCM under argon, and the mixture was cooled down to
0 ⁰C. To the reaction mixture 0.20g (0.8mmol) of PPh3 was added and after 10 min 0.14g
(0.8mmol) of NBS. After stirring for 40min at 0 ⁰C the reaction mixture was worked up with
saturated sodium bicarbonate solution, extracted with DCM(3x30ml), organic fractions were
combined and the solvent removed on a rotary evaporator. The remaining oil was purified on a
silica gel column with 1% EtOAc/hexanes solvent yielding 0.37g (93%) of pure 2.19.
1
H NMR
(400MHz, CDCl3) 7.71 - 7.58 (m, 4H), 7.46 - 7.33 (m, 6H), 6.17 (dd, J = 15.9, 5.4 Hz, 1H), 5.65
(dtd, J = 15.9, 2.2, 1.6 Hz, 1H), 5.42-5.33 (m, 1H), 5.23 - 5.13 (m, 1H), 4.25 - 4.19 (m, 1H), 4.06
(d, J = 2.3 Hz, 2H), 2.27 - 2.07 (m, 2H), 1.82 - 1.71 (m, 2H), 0.84 (t, J = 7.5 Hz, 3H).
13
C NMR
(600MHz, CDCl3) 147.17, 136.02, 135.99, 134.45, 134.10, 133.65, 129.89, 129.87, 127.74,
123.17, 108.48, 85.41, 84.44, 73.17, 35.51, 27.16, 20.71, 19.50, 15.73, 14.22.

2.22
(S,4E,8Z)-1-Bromoundeca-4,8-dien-2-yn-6-ol (2.22): The reaction was done on 0.4g
(1mmol) of 2.18. After following the procedure described for compound 2.19 the resulting oil (no
purification was done) was dissolved in 3ml of THF and 2ml (2mmol) of 1M TBAF was added.
The reaction mixture was stirred for 3h after which the solvent was removed and the remaining
fraction was purified on a silica gel column with 12% EtOAc/hexanes furnishing 0.2g (0.8mmol)
of 2.22. 1H NMR (400MHz, CDCl3) 6.26 (ddd, J = 15.9, 5.3, 1.8 Hz, 1H), 5.87 - 5.74 (m, 1H),
5.62 (dtq, J = 10.8, 7.3, 1.7 Hz, 1H), 5.38 - 5.30 (m, 1H), 5.14 (d, J = 2.0 Hz, 1H), 5.02 (d, J = 2.0
Hz, 1H), 4.23 (p, J = 6.5 Hz, 1H), 2.38 - 2.28 (m, 2H), 2.05 (s, 2H), 1.01 - 0.95 (m, 3H).
13
C NMR
49

(400MHz, CDCl3) 146.95, 136.31, 129.79, 108.69, 84.94, 77.36, 72.04, 53.56, 36.24, 26.72, 20.86,
18.92, 14.27.

2.20
Methyl (4Z,7S,8E,15E,17S,19Z)-7,17-bis((tert-butyldiphenylsilyl)oxy) docosa-
4,8,15,19-tetraen-10,13-diynoate (2.20): 50ml flask was flame-dried and filled with argon gas.
In the flask, a mixture of 0.09g (0.5mmol) of CuI, 0.07g (0.5mmol) of NaI, 0.07g (0.5mmol) of
K2CO3 and 0.1g of MS4Å was added and dissolved in 5ml of DMF under argon. Then, 0.17g
(0.4mmol) of 2.19 and 0.14g (0.3mmol) of 2.11 were cannulated in 4ml of anhydrous DMF under
argon. The reaction mixture was stirred for overnight under argon, worked up with saturated
ammonium chloride and extracted with Et2O (4x40ml). The organic fractions were combined,
solvent removed and the purification on a silica gel column with 2% EtOAc/hexanes yielded 0.2g
(74%) of 2.20.
1
H NMR (600MHz, CDCl3) 7.75 - 7.54 (m, 8H), 7.47 - 7.29 (m, 12H), 6.10 (td, J
= 15.7, 5.6 Hz, 2H), 5.66 - 5.53 (m, 2H), 5.40 - 5.25 (m, 3H), 5.23 - 5.10 (m, 1H), 4.21 (dq, J =
12.9, 5.6 Hz, 2H), 3.65 (s, 3H), 3.41 (s, 1H), 2.28-2.06 (m, 8H), 1.76 (dq, J = 13.3, 6.6 Hz, 2H),
0.83 (t, J = 7.5 Hz, 3H).
13
C NMR (600MHz, CDCl3) 173.60, 145.38, 145.10, 136.04, 136.02,
134.27, 134.25, 134.20, 133.77, 133.69, 129.99, 129.87, 129.83, 129.80, 127.74, 127.72, 127.71,
125.76, 123.41, 109.47, 109.22, 83.85, 83.62, 79.20, 79.08, 73.30, 73.06, 51.65, 35.61, 35.52,
33.97, 27.18, 22.95, 20.71, 19.51, 19.50, 14.23, 11.30.

2.23
Methyl (4Z,7S,8E,15E,17S,19Z)-7,17-dihydroxydocosa-4,8,15,19-tetraen-10,13-
diynoate (2.23): The procedure described for compound 2.20 was followed with 0.02g
50

(0.08mmol) of 2.22 and 0.03g (0.14mmol) of 2.21. Yield: 0.013g (45%) of 2.23.
1
H NMR
(600MHz, CDCl3) 6.21 - 6.04 (m, 2H), 5.82 - 5.66 (m, 2H), 5.63 - 5.49 (m, 2H), 5.48 - 5.28 (m,
2H), 4.25 - 4.10 (m, 2H), 3.67 (s, 3H), 3.42 (s, 1H), 2.49-2.25 (m, 8H), 2.06 (p, J = 7.5 Hz, 3H),
0.97 (td, J = 7.5, 1.1 Hz, 3H).
13
C NMR (600MHz, CDCl3) 173.85, 145.07, 145.04, 136.17, 136.01,
131.60, 125.91, 123.24, 123.10, 109.89, 109.84, 84.17, 84.15, 78.87, 78.83, 77.37, 77.16, 76.95,
71.64, 71.43, 51.83, 35.13, 35.03, 33.74, 22.90, 20.90, 14.33, 11.28.

2.24
Methyl(4Z,7S,8E,10Z,13Z,15E,17S,19Z)-7,17-bis((tert-butyldiphenylsilyl)oxy)
docosa-4,8,10,13,15,19-hexaenoate (2.24): 0.02 g (0.02mmol) of 2.20 was dissolved in 1ml of
EtOAc and 0.1ml of pyridine, 0.1ml of 1-octene and 0.1g of Lindlar catalyst were added. The
reaction mixture was stirred for 2 days and monitored by TLC every 6h. If the reaction goes too
slow, it is suggested to add 0.1-0.2g of Lindlar catalyst more (no overhydrogenation was
observed). After TLC showed completion, solvent was removed and the mixture was purified on
a silica gel column with 1% of EtOAc/hexanes yielding 0.013g (62%) of 2.24.
1
H NMR (600MHz,
CDCl3) 6.15 (ddd, J = 15.1, 11.1, 4.0 Hz, 2H), 5.87 (td, J = 10.9, 2.6 Hz, 2H), 5.61 (dt, J = 15.0,
7.5 Hz, 2H), 5.43 - 5.14 (m, 6H), 4.21 (p, J = 5.9 Hz, 2H), 3.64 (s, 3H), 2.76 (t, J = 7.5 Hz, 2H),
2.36 - 2.08 (m, 8H), 1.85 (p, J = 7.6 Hz, 2H), 1.08 - 1.06 (m, 9H), 1.06 - 1.04 (m, 9H), 0.85 (t, J =
7.5 Hz, 3H).
13
C NMR (400MHz, CDCl3) 173.68, 136.23, 136.13, 136.08, 136.07, 135.94, 134.51,
134.26, 134.17, 133.78, 129.73, 129.69, 129.66, 129.63, 129.53, 129.44, 129.21, 128.62, 128.50,
127.63, 127.61, 127.53, 127.52, 126.56, 125.40, 125.19, 124.20, 110.16, 74.09, 73.90, 51.65,
36.09, 34.06, 27.19, 26.42, 23.04, 20.78, 19.50, 14.30.

51

2.25
Methyl (4Z,7S,8E,10Z,13Z,15E,17S,19Z)-7,17-dihydroxydocosa-4,8,10,13,15,19-
hexaenoate (2.25): 13mg (0.015mmol) of 2.24 was dissolved in 2ml of THF and 0.06ml of 1M
TBAF (0.06mmol) was added. The reaction mixture was stirred for 8h, solvent removed and the
remaining oil was purified on a silica gel column using 35% EtOAc/hexanes solvent yielding
3.5mg (65%) of 2.25.
1
H NMR (600MHz, CDCl3) 6.59 (dddt, J = 15.1, 11.2, 5.4, 1.3 Hz, 2H), 6.02
(t, J = 10.9 Hz, 2H), 5.74 (dd, J = 15.2, 6.0 Hz, 2H), 5.62-5.32 (m, 6H), 4.24 (dq, J = 12.2, 6.2 Hz,
2H), 3.67 (s, 3H), 3.09 (t, J = 7.8 Hz, 2H), 2.37 (tdq, J = 21.5, 14.3, 7.1 Hz, 8H), 2.07 (dt, J = 14.5,
6.8 Hz, 3H), 0.97 (t, J = 7.5 Hz, 3H).
13
C NMR (600MHz, CDCl3) 173.86, 136.12, 136.08, 135.45,
131.10, 129.71, 129.67, 128.42, 128.39, 126.43, 125.38, 123.84, 109.98, 72.03, 71.86, 51.81,
35.50, 35.43, 33.86, 26.75, 22.98, 20.91, 14.36.

2.26
Octa-2,5-diyn-1-ol (2.26): 50ml flask was flame-dried and filled with argon gas. Propargyl
alcohol (0.6g, 10.7mmol) and 1-bromo-2-pentyne (1.0g, 6.8mmol) were dissolved in 4ml of
anhydrous DMF and cannulated to the mixture of CuI (1.9g, 10.0mmol), NaI (1.5g, 10.0mmol)
and K2CO3 (1.4g, 10.0mmol) in 10ml of anhydrous DMF under argon. The reaction mixture was
treated with saturated ammonium chloride aqueous solution and extracted with diethyl ether
(4x30ml). The combined organic layer was washed twice with 100ml of water and dried over
sodium sulfate. After filtering it out and removing the solvent the mixture was purified on a silica
column with 10% EtOAc/hexanes to afford the product (0.8g, 96%).
1
H NMR (400MHz, CDCl3)
4.27 (s, 2H), 3.19 (p, J = 2.3 Hz, 3H), 2.18 (qt, J = 7.5, 2.4 Hz, 3H), 1.12 (t, J = 7.5 Hz, 3H).

52

2.27
(E)-oct-2-en-5-yn-1-ol (2.27): 50ml flask was flame-dried and filled with argon gas. In the
flask 8ml of 1M LiAlH4 solution in diethyl ether was added under argon, and then the flask was
cooled down to 0 ⁰C. Then, alcohol 3.1 (0.8g, 6.6mmol) in 9ml of anhydrous diethyl ether was
cannulated under argon. The mixture was let to warm up to room temperature and then refluxed
overnight. Reaction mixture was cooled to 0 ⁰C, quenched with 50ml of water, extracted 4 times
(30ml) with diethyl ether and dried over sodium sulfate. After filtering the mixture out and
removing the solvent on the rotary evaporator, it was purified on a column with 10%
EtOAc/hexanes solvent (0.66g, 81%).
1
H NMR (400MHz, CDCl3) 5.92 (dtt, J = 15.1, 5.7, 1.8 Hz,
1H), 5.70 (dtt, J = 15.2, 5.3, 1.4 Hz, 1H), 4.15 (tq, J = 5.8, 1.4 Hz, 2H), 3.04 - 2.83 (m, 2H), 2.20
(qt, J = 7.5, 2.4 Hz, 2H), 1.33 - 1.23 (m, 2H), 1.14 (t, J = 7.5 Hz, 3H).

2.28
(2R,3R)-oct-5-yne-1,2,3-triol (2.28): 2.2g of AD-mix- and 0.16g (1.7mmol) of
methylsulfonamide were transferred to 18ml of 1:1 water : t-butanol solvent and stirred for 30min
at room temperature. The mixture was cooled down to 0 ⁰C and 0.2g (1.6mmol) of alcohol 2.27
was added with a pipet in 4ml of 1:1 water:t-butyl alcohol. After stirring overnight at 0 ⁰C the
reaction was treated with 2.4g of sodium sulfite and 50ml of water and stirred for additional 30min
at room temperature. After extraction with ethyl acetate (20x20ml) and drying over sodium sulfate,
the mixture was filtered out and the solvent removed yielding 0.2g (78%) of pure triol 2.28.
1
H
NMR (400MHz, CDCl3) 3.85 - 2.48 (m, 4H), 2.63 (d, J = 5.7 Hz, 1H), 2.49 (dt, J = 6.3, 2.5 Hz,
6H), 2.18 (qt, J = 7.5, 2.4 Hz, 2H), 2.09 (dd, J = 6.7, 4.7 Hz, 1H), 1.13 (t, J = 7.5 Hz, 3H).
13
C
NMR (400MHz, CDCl3) 77.36, 72.61, 71.22, 64.94, 60.55, 24.46, 21.21, 14.36.

53

2.29
(2R,3R)-1,2,3-tris-(tert-butyldimethylsilyloxy)-oct-5-yne (2.29): 250ml flask was
flame-dried and filled with argon gas. In the flask a mixture of 4.3g (28.6mmol) of t-
butyldimethylsilylchloride, 0.2g (1.6mmol) dimethylaminopyridine and 2.0g (29.4mmol) of
imidazole was dissolved in 40ml of anhydrous DCM and 0.45g (2.8mmol) of 2.28 was cannulated
at 0 ⁰C, allowed to warm to room temperature, and stirred overnight under argon. The reaction
was treated with 200ml of saturated ammonium chloride solution and extracted with 4x30ml of
dichloromethane. Combined organic fraction was dried over sodium sulfate, filtered out, solvent
removed and purified on a column with hexanes yielding 1.1 g (2.2mmol, 77%) of 2.29.
1
H NMR
(400MHz, CDCl3) 3.84-3.74 (m, 1H), 3.76 - 3.69 (m, 2H), 3.50 - 3.42 (m, 1H), 2.54 - 2.44 (m,
1H), 2.19 - 2.08 (m, 3H), 1.10 (t, J = 7.4 Hz, 3H), 0.89 (s, 9H), 0.88 (s, 9H), 0.10 (s, 3H), 0.08 (s,
3H), 0.07 (s, 6H), 0.04 (s, 6H).
13
C NMR (400MHz, CDCl3) 77.36, 75.26, 72.70, 63.79, 31.75,
26.15, 26.00, 25.95, 22.82, 22.66, 18.29, 14.31, 12.62, -4.06, -4.24, -4.61, -4.75, -5.08, -5.21.

2.30
(2R,3R)-2,3-di-(tert-butyldimethylsilyloxy)-oct-5-ynol (2.30): 3ml of 70% of Py·HF
solution was added at 0 ⁰C to a plastic vial containing 6ml of pyridine and 15ml of THF. 1ml of
the prepared solution was added to 0.37g (0.74mmol) of 2.29 in 10ml of THF at 0 ⁰C, warmed up
to room temperature and stirred overnight. The reaction mixture was cooled to 0 ⁰C and quenched
with 50ml of saturated sodium bicarbonate solution. After extraction with diethyl ether (4x30ml)
the combined organic phase was dried over sodium sulfate, filtered out, solvent removed and the
remaining fraction was purified with 4% EtOAc/hexanes solvent furnishing 0.20g (70%) of 2.30.
1
H NMR (400MHz, CDCl3) 3.94-3.77 (m, 2H), 3.73 (dt, J = 10.8, 5.1 Hz, 1H), 3.58 (dddd, J =
11.0, 6.9, 5.5, 1.2 Hz, 1H), 2.68-2.45 (m, 1H), 2.34-2.19 (m, 2H), 2.20 2.10 (m, 2H), 1.11 (t, J =
7.6 Hz, 3H), 0.91 (s, 9H), 0.90 (s, 9H), 0.15 (s, 3H), 0.11 (s, 3H), 0.10 (s, 3H), 0.09 (s, 3H).
13
C
54

NMR (400MHz, CDCl3) 82.97, 77.52, 74.61, 73.37, 63.32, 25.93, 25.91, 25.86, 21.90, 18.20,
14.24, 12.64, -4.31, -4.53, -4.55, -4.59.

2.31
(2R,3R,Z)-2,3-di-(tert-butyldimethylsilyloxy)-oct-5-enal (3.6): Compound 2.30 (0.17g,
0.44 mmol) was dissolved in 20ml of EtOAc and 0.05ml of quinoline and 20mg of Lindlar catalyst
were added. The reaction mixture was purged with hydrogen and monitored by TLC. After the
completion, the reaction mixture was filtered out, solvent removed and the remaining fraction was
dissolved in 20ml of regular dichloromethane. After the addition of 0.5ml (6.2mmol) of pyridine,
0.21g (0.50mmol) of Dess-Martin periodinane was added. After 20min the reaction mixture was
worked up with 50ml of sodium thiosulfate-sodium bicarbonate solution, extracted with
dichloromethane (4x30ml) and dried over sodium sulfate. Sodium sulfate was filtered out, solvent
removed and the remaining mixture was purified on a column with 5% EtOAc/hexanes yielding
0.15g (0.39mmol, 88%) of the aldehyde 2.31.
1
H NMR (400MHz, CDCl3) 9.77 (d, J = 0.9 Hz,
1H), 5.50 - 5.40 (m, 1H), 5.37 - 5.29 (m, 1H), 4.00 (dd, J = 4.6, 0.9 Hz, 1H), 3.90 (dt, J = 7.3, 4.7
Hz, 1H), 2.48 - 2.38 (m, 1H), 2.16 (dt, J = 15.5, 7.4, 1H), 2.07 - 1.95 (m, 2H), 0.95 (t, J =8.3 , 3H),
0.93 (s, 9H), 0.89 (s, 9H), 0.09 (s, 3H), 0.07 (s, 3H), 0.07 (s, 3H), 0.05 (s, 3H). 13C NMR (400MHz,
CDCl3) 203.43, 134.50, 124.78, 79.97, 75.02, 31.75, 30.57, 25.88, 25.86, 22.82, 20.88, 18.14,
14.28, -4.27, -4.38, -4.59, -5.04.

2.32
(3Z,6R,7R,8E,10E)-6,7-di-(tert-butyldimethylsilyloxy)-13,13-dibromotrideca-
3,8,10,12 -tetraene (2.32): 5ml pear-shaped flask was flame-dried and filled with argon gas. In
the flask, aldehyde 2.31 (0.4g, 1.0mmol) was dissolved in 1ml of anhydrous benzene with 0.7g
(2.3mmol) of triphenylphosphoranylidene acetaldehyde and 0.05g of molecular sieves 4Å and the
55

reaction mixture was refluxed at 85 ⁰C. The reaction progress was carefully monitored by TLC.
After 20h the reaction mixture showed completion, was dried down, and flashed through a column
with hexanes (separation of the products was not possible). Fractions containing the mixture of the
products were combined and solvent was removed. To a 25ml flame-dried round-bottom flask
under argon, 1.4g (4.2mmol) of tetrabromomethane and 1.6g (6.1mmol) of triphenylphosphine
was dissolved in 10ml of anhydrous DCM at 0 ⁰C, and allowed to stir for 30min. The mixture that
was obtained from previous purification step dissolved in 5ml of anhydrous DCM was cannulated
to the reaction mixture at 0 ⁰C under argon. The reaction was allowed to warm up to room
temperature, stirred for 30 more minutes, worked up with saturated sodium bicarbonate solution
and extracted with dichloromethane (4x30ml). The combined organic layer was dried over sodium
sulfate, filtered out and the solvent was evaporated. The remaining oily mixture was successfully
purified with pure hexanes as a solvent furnishing 0.32g (0.54mmol, 52%) of the desired product
2.32.
1
H NMR (400MHz, CDCl3) 6.95 (dd, J = 10.3, 0.8, 1H), 6.43 (dd, J = 14.8, 10.7, 1H), 6.36-
6.25 (m, 1H), 6.16 (dd, J = 14.7, 10.5, 1H), 6.02 (dd, J = 15.0, 4.5, 1H), 5.47-5.30 (m, 2H), 4.20
(dt, J = 4.5, 2.3 , 1H), 3.59 (ddd, J = 8.9, 4.6, 3.1 Hz, 1H), 2.39-2.26 (m, 1H), 2.10-1.92 (m, 2H),
1.82-1.65 (m, 1H), 0.95 (t, J = 8.3 Hz, 3H), 0.92 (s, 9H), 0.89 (s, 9H), 0.06 (s, 6H), 0.05 (s, 3H),
0.05 (s, 3H).
13
C NMR (400MHz, CDCl3) 137.33, 137.00, 136.19, 133.00, 129.72, 127.78, 126.60,
76.30, 75.12, 66.02, 34.29, 31.75, 29.36, 26.01, 25.99, 22.82, 22.50, 14.28, -4.27, -4.52, -4.67.

2.33
(3Z,6R,7R,8E,10E)- 6,7-di-(tert-butyldimethylsilyloxy)-trideca-3,8,10-trien-12-yne
(2.33): 10ml round-bottom flask was flame-dried and filled with argon gas. In the flask 0.09g
(0.15mmol) of tetraene 2.32 and 0.1g of molecular sieves 4Å were dissolved in 1ml of anhydrous
THF. The reaction mixture was cooled down to -78 ⁰C and 0.4ml (0.8mmol) of 2M solution of
LDA was added dropwise. After stirring for 2h the reaction mixture was worked up with saturated
ammonium chloride solution, extracted with dichloromethane (4x30ml), solvent was removed and
the remaining fraction was purified on a silica column with hexanes solvent furnishing 0.06g
56

(0.14mmol, 91%) of the product 2.33.
1
H NMR (400MHz, CDCl3) 6.73 (ddd, J = 15.7, 11.0, 0.8,
1H), 6.30 (dddd, J = 15.2, 10.8, 1.7, 0.6, 1H), 5.99 (dd, J = 15.3, 4.4, 1H), 5.56-5.49 (m, 1H), 5.45-
5.30 (m, 2H), 4.22 (td, J = 4.5, 1.7, 1H), 3.59 (ddd, J = 8.8, 4.8, 3.1, 1H), 3.00 (d, J = 2.3, 1H),
2.37-2.27 (m, 1H), 2.06-1.95 (m, 2H), 1.89-1.82 (m, 1H), 0.96-0.90 (m, 12H), 0.9-0.87 (s, 9H),
0.06-0.05 (s, 6H), 0.05-0.03 (m, 6H).
13
C NMR (400MHz, CDCl3) 143.56, 136.88, 133.01, 129.20,
126.59, 108.95, 83.23, 79.17, 77.36, 76.26, 74.91, 29.32, 29.03, 25.99, 25.95, 20.74, 18.31, 14.40,
-4.30, -4.60, -4.68.

2.36
(S)-methyl 8-((tert-butyldimethylsilyl)oxy)-7-hydroxyoct-4-ynoate (2.36): 25ml pear-
shaped flask was flame-dried and filled with argon gas. In the flask, a mixture of 0.54g (4.8mmol)
of 2.34 and 1.27g (6.7mmol) of 2.35 was dissolved in 5ml of THF under -78 ⁰C. Then, 0.67ml
(5.3mmol) of BF3·OEt2 and 5.3ml (5.3mmol) of 1M NaHMDS solution were added at the same
time dropwise for 2min. The mixture was stirred for 3.5h at -78 ⁰C and quenched with saturated
ammonium chloride solution. The mixture was extracted with dichloromethane (3x30ml), dried
over sodium sulfate, solvent removed and the remaining fraction was purified on a silica column
with 12% EtOAc/hexanes yielding 0.6g (2.0mmol, 41%) of 2.36.
1
H NMR (400MHz, CDCl3)
3.78-3.56 (m, 6H), 2.55-2.45 (m, 4H), 2.39-2.35 (m, 2H), 0.90 (s, 9H), 0.08 (s, 6H).

2.37
(S)-methyl 8-((tert-butyldimethylsilyl)oxy)-7-((tert-butyldiphenylsilyl)oxy)oct-4-
ynoate (3.12): 100ml round-bottom flask was flame-dried and filled with argon gas. In the flask
0.55g (1.8mmol) of 2.36, 0.15g (2.2mmol) of imidazole, 0.05g(0.4mmol) dimethylaminopyridine
were dissolved in 20ml of dichloromethane and then 0.57ml (2.2mmol) of
tertbuthyldiphenylsilylchloride was added under argon. After 15h the mixture was worked up with
57

saturated ammonium chloride solution, extracted with dichloromethane, dried down on the rotary
evaporator and purified on a silica column with 5% EtOAc/hexanes solvent yielding 0.86g
(1.6mmol, 87%) of 2.37.
1
H NMR (400MHz, CDCl3) 7.74-7.65 (m, 4H), 7.46-7.32 (m, 6H), 3.80
(p, J = 5.4 Hz, 1H), 3.67 (s, 3H), 3.53 (dd, J = 5.4, 1.0 Hz, 2H), 2.43 (dddd, J = 10.2, 9.3, 6.9, 4.6
Hz, 4H), 2.35 (dt, J = 5.8, 2.1 Hz, 1H), 2.28 (dt, J = 5.4, 2.2 Hz, 1H), 1.06 (s, 9H), 0.83 (s, 9H), -
0.04 (s, 3H), -0.07 (s, 3H).

2.38
(S)-methyl 7-((tert-butyldiphenylsilyl)oxy)-8-hydroxyoct-4-ynoate (2.38): 0.86g
(1.6mmol) of compound 2.37 was dissolved in 26ml of dichoromethane mixed with 26ml of
methanol and 0.18g (0.8mmol) of camphorsulfonic acid was added upon vigorous stirring under
argon. The reaction was monitored by TLC every 15min. After 1h TLC showed that the reaction
was completed and it was quenched with 0.45ml (3.2mmol) of triethylamine. The solvent was
removed and the mixture was purified on a silica column with 12% EtOAc/hexanes solvent which
yielded 0.62g (1.5mmol, 92%) of 2.38.
1
H NMR (400MHz, CDCl3) 7.70-7.62 (m, 4H), 7.47-7.33
(m, 6H), 3.76 (dtd, J = 7.1, 5.2, 3.5 Hz, 1H), 3.65 (s, 3H), 3.50 (qd, J = 11.9, 4.6 Hz, 2H), 2.25-
2.17 (m, 2H), 2.17 (d, J = 0.4 Hz, 1H), 1.56-1.35 (m, 4H), 1.07 (s, 3H).
13
C NMR (400MHz,
CDCl3) 136.04, 135.85, 129.96, 127.91, 127.80, 77.36, 74.14, 66.13, 34.09, 33.49, 29.18, 27.23,
24.87.

2.39
(S,Z)-methyl 7-((tert-butyldiphenylsilyl)oxy)-8-oxooct-4-enoate (2.39): 0.62g
(1.5mmol) of 2.38 was dissolved in 40ml of ethyl acetate and 0.1ml of quinoline and 20mg of
Lindlar catalyst were added. The reaction mixture was purged with hydrogen and carefully
monitored by the TLC (10%EtOAc/hexanes). After the reaction completion, the mixture was
58

filtered out, solvent was evaporated and the remaining oil was dissolved in 30ml of regular
dichloromethane. 2ml of pyridine and 0.68g (1.6mmol) of Dess-Martin periodinane was added
under vigorous stirring at room temperature. After 15min the reaction mixture was quenched with
sodium bicarbonate-sodium thiosulfate solution and extracted with 3x30ml dichloromethane. The
organic layer was separated and the solvent was removed. The remaining oily mixture was purified
on a silica column with 15% EtOAc/hexanes solvent giving 0.58g (94%) of the desired product.
1
H NMR (400MHz, CDCl3) 9.56 (d, J = 1.6 Hz, 1H), 7.67 - 7.60 (m, 4H), 7.48 - 7.32 (m, 6H),
5.45 - 5.39 (m, 2H), 4.06 (ddd, J = 6.4, 5.6, 1.6 Hz, 1H), 3.65 (s, 3H), 2.46 (dt, J = 14.9, 5.9 Hz,
1H), 2.35 (dt, J = 16.1, 5.8 Hz, 1H), 2.31 - 2.21 (m, 4H), 1.11 (s, 9H).
13
C NMR (400MHz, CDCl3)
203.44, 173.53, 135.95, 135.94, 130.92, 130.22, 130.18, 127.98, 127.93, 124.56, 53.57, 51.70,
33.85, 31.74, 27.08, 22.81, 14.27.

2.40
(S,4Z,8E)-methyl 7-((tert-butyldiphenylsilyl)oxy)-9-iodonona-4,8-dienoate (2.40):
25ml pear-shaped flask was flame-dried and filled with argon gas. In the flask 0.59g (4.8mmol)
chromium(II) chloride was mixed with 4ml of anhydrous THF under argon. Then, 0.56g
(1.4mmol) of iodoform and 0.1g (0.2mmol) of 2.39 dissolved in 2ml of anhydrous THF were
cannulated at 0 ⁰C under argon. The reaction mixture was stirred at 0 ⁰C for 4h after which it was
worked up with 100ml of saturated ammonium chloride solution and extracted with 3x30ml of
dichloromethane. Solvent was removed and the mixture was purified on a silica column with pure
pentane, then with 5% ethyl ether/pentane solvent yielding 0.06g (46%) of 2.40.
1
H NMR
(400MHz, CDCl3) 7.69-7.57 (m, 4H), 7.48-7.31 (m, 6H), 6.47 (dd, J = 14.4, 6.6 Hz, 1H), 5.98 (dd,
J = 14.4, 1.1 Hz, 1H), 5.44 - 5.26 (m, 2H), 4.22-4.00 (m, 1H), 3.65 (s, 3H), 2.30-2.17 (m, 6H),
1.06 (s, 9H).
13
C NMR (400MHz, CDCl3) 173.59, 147.85, 136.08, 136.03, 136.01, 136.00, 133.90,
133.58, 130.29, 129.93, 129.90, 127.77, 127.74, 125.55, 75.70, 51.69, 34.02, 31.75, 27.12, 22.81,
14.27.
59

2.41
(4Z,7S,8E,12E,14E,16R,17R,19Z)-methyl-16,17-bis((tert-butyldimethylsilyl)oxy)-7
((tert-butyldiphenylsilyl)oxy)docosa-4,8,12,14,19-pentaen-10-ynoate (2.41): 10ml round-
bottom flask was flame-dried and filled with argon gas. In the flask 0.02g (0.04mmol) of the vinyl
iodide 2.40 was dissolved in 3ml of n-buthylamine and 2mg (0.009mmol) of Pd(OAc)2 with 4mg
(0.015mmol) of PPh3 were added. The reaction mixture was stirred for 15min under argon and
0.02g (0.05mmol) of alkyne 2.33 was added in 2ml of n-buthylamine. After stirring for overnight
at room temperature the solvent was removed on a rotary evaporator and the mixture was purified
on a silica column with 3% EtOAc/hexanes furnishing 0.03g (88%) of the compound 2.41.
1
H
NMR (400MHz, CDCl3) 7.95-7.55 (m, 4H), 7.47-7.28 (m, 6H), 6.62 (dd, J = 15.4, 11.0, 1H), 6.29
(ddd, J = 15.4, 11.0, 1.7, 1H), 6.06 (dd, J = 15.7, 5.7, 1H), 5.94 (dd, J = 15.2, 4.8, 1H), 5.75-6.60
(m, 2H), 5.51-5.12 (m, 4H), 4.33-4.12 (m, 2H), 3.64 (s, 3H), 3.62-3.55 (m, 1H), 2.27-2.16 (m, 3H),
2.16-2.07 (m, 3H), 2.06-1.95 (m, 2H), 1.95-1.83 (m, 2H), 1.37-1.16 (m, 27H), 0.95 (t, J = 7.9, 3H),
0.05 (s, 6H), 0.04 (s, 6H). 13C NMR (600MHz, CDCl3) 173.63, 144.73, 141.55, 134.21, 133.97,
133.81, 133.71, 132.98, 130.02, 129.87, 129.83, 129.73, 129.18, 128.85, 128.66, 128.60, 128.37,
127.74, 127.72, 126.63, 125.76, 110.35, 109.98, 90.30, 89.73, 77.41, 77.16, 76.91, 73.23, 51.64,
36.25, 35.62, 34.83, 34.69, 33.97, 31.76, 22.96, 21.20, 18.92, 14.35, -4.29, -4.30, -4.56, -4.67.

60

2.42
(4Z,7S,8E,12E,14E,16R,17R,19Z)-methyl 7,16,17-trihydroxy- docosa-4,8,12,14,19-
pentaen-10-ynoate (2.42): 10ml round-bottom flask was flame-dried and filled with argon gas. In
the flask 10.0mg (0.012mmol) of 2.41 was dissolved in 2ml of anhydrousTHF and 0.2ml of 1M
TBAF (0.2mmol) was added under argon. The mixture was stirred overnight at room temperature
and then solvent was removed on a rotary evaporator. The remaining oily mixture was purified on
a silica column with 50% EtOAc/hexanes solvent yielding 2.2mg (45%) of 2.42.
1
H NMR
(600MHz, CDCl3) 6.58 (dd, J = 15.3, 11.1, 1H), 6.37 (t, J = 13.1, 1H), 6.17 (dd, 15.8, 5.5, 1H),
5.90 (d, J = 15.6, 1H), 5.80 (dd, J = 15.2, 6.3, 1H), 5.75 (d, J = 15.7, 1H), 5.63-5.49 (m, 2H), 5.49-
5.30 (m, 2H), 4.25 (q, J = 5.9, 1H), 4.05 (t, J = 6.6, 1H), 3.67 (s, 3H), 3.54 (q, J = 6.1, 1H), 2.47-
2.33 (m, 6H), 2.33-2.22 (m, 2H), 2.17 (d, J = 2.4, 1H), 2.13 (d, J = 2.13, 1H), 2.10-2.01 (m, 2H),
0.97 (t, J = 7.3, 3H).
13
C NMR (600MHz, CDCl3) 173.88, 145.07, 140.59, 135.65, 134.68, 131.95,
131.64, 125.88, 123.73, 112.39, 110.11, 90.87, 89.55, 74.94, 74.24, 71.49, 51.83, 35.16, 33.71,
31.74, 22.89, 21.20, 14.35.

2.43
(4Z,7S,8E,10Z,12E,14E,16R,17R,19Z)-methyl-7,16,17-trihydroxy-docosa-
4,8,10,12,14, 19-hexaenoate (2.43): 25ml three-neck flask was flame-dried and filled with argon
gas. In the flask 0.4g of Zn/Cu/Ag catalysts, prepared beforehand by the known procedure
22,42,52
,
1ml of freeze-thaw degassed HPLC grade water was added under argon, and the mixture was
61

stirred for a couple of minutes to wet the catalyst and then 2mg (0.005mmol) of 2.42 dissolved in
1ml of HPLC grade methanol was transferred also under argon. The mixture was stirred for 7h
under argon, and then filtered out. Solvent was removed on a rotary evaporator and the resulting
oil was purified by HPLC with 42% HPLC grade water/methanol solvent furnishing 0.6g (30%)
of the compound 2.43.
1
H NMR (600MHz, CDCl3) 6.78-6.68 (m, 2H), 6.42 (dd, J = 15.4, 10.8,
1H), 6.25 (dd, J = 15.0, 10.8, 1H), 6.06-5.98 (m, 2H), 5.77 (ddd, J = 27.6, 14.9, 6.4, 1H), 5.62-
5.44 (m, 3H), 5.40 (q, J = 8.5, 1H), 4.32-4.23 (m, 1H), 4.05 (q, J = 5.8, 1H), 3.68 (s, 3H), 3.58-
3.50 (m, 1H), 2.47-2.33 (m, 6H), 2.33-2.26 (m, 2H), 2.25 (d, J = 4.2, 1H), 2.13 (d, J = 3.7, 1H),
2.07 (p, J = 7.3, 6.8, 2H), 1.99 (d, J = 4.2, 1H), 0.97 (t, J = 7.6, 3H).
13
C NMR (600MHz, CDCl3)
173.84, 137.08, 135.55, 133.12, 132.81, 131.33, 129.62, 129.54, 128.99, 126.29, 125.59, 123.88,
75.36, 74.37, 71.88, 51.82, 35.54, 33.56, 32.09, 22.86, 20.87, 14.35.

62

2.5 Spectra

Figure 2.1:
1
H NMR spectrum of compound 2.4
63

Figure 2.2:
1
H NMR spectrum of compound 2.5
64

Figure 2.3:
1
H NMR spectrum of compound 2.6
65

Figure 2.4:
1
H NMR spectrum of compound 2.7
66

Figure 2.5:
13
C NMR spectrum of compound 2.7

67

Figure 2.6:
1
H NMR spectrum of compound 2.8
68

Figure 2.7:
13
C NMR spectrum of compound 2.8
69

Figure 2.8:
1
H NMR spectrum of compound 2.9
70

Figure 2.9:
13
C NMR spectrum of compound 2.9
71

Figure 2.10:
1
H NMR spectrum of compound 2.10
72

Figure 2.11:
13
C NMR spectrum of compound 2.10
73

Figure 2.12:
1
H NMR spectrum of compound 2.11

74

Figure 2.13:
13
C NMR spectrum of compound 2.11
75

Figure 2.14:
1
H NMR spectrum of compound 2.18
76

Figure 2.15:
13
C NMR spectrum of compound 2.18
77

Figure 2.16:
1
H NMR spectrum of compound 2.19
78

Figure 2.17:
13
C NMR spectrum of compound 2.19
79

Figure 2.18:
1
H NMR spectrum of compound 2.20
80

Figure 2.19:
1
H NMR spectrum of the olefinic region of compound 2.20
81

Figure 2.20:
13
C NMR spectrum of compound 2.20
82

Figure 2.21:
1
H NMR spectrum of compound 2.21
83

Figure 2.22:
13
C NMR spectrum of compound 2.21
84

Figure 2.23:
1
H NMR spectrum of compound 2.22
85

Figure 2.24:
13
C NMR spectrum of compound 2.22
86

Figure 2.25:
1
H NMR spectrum of compound 2.23
87

Figure 2.26:
1
H NMR spectrum of the olefinic region of compound 2.23
88

Figure 2.27:
13
C NMR spectrum of compound 2.23
89

Figure 2.28: 2D
1
H-
1
H COSY NMR spectrum of compound 2.23
90

Figure 2.29:
1
H NMR spectrum of compound 2.24
91

Figure 2.30:
1
H NMR spectrum of the olefinic region of compound 2.24
92

Figure 2.31:
13
C NMR spectrum of compound 2.24
93

Figure 2.32: 2D
1
H-
1
H COSY NMR spectrum of compound 2.24
94

Figure 2.33:
1
H NMR spectrum of compound 2.25
95

Figure 2.34:
1
H NMR spectrum of the olefinic region of compound 2.25
96

Figure 2.35:
13
C NMR spectrum of compound 2.25
97

Figure 2.36: 2D
1
H-
1
H COSY NMR spectrum of compound 2.25
98

Figure 2.37: 2D NOESY NMR spectrum of compound 2.25
99

Figure 2.38:
1
H NMR spectrum of compound 2.26

100

Figure 2.39:
1
H NMR spectrum of compound 2.27

101

Figure 2.40:
1
H NMR spectrum of compound 2.28

102

Figure 2.41:
13
C NMR spectrum of compound 2.28

103

Figure 2.42:
1
H NMR spectrum of compound 2.29

104

Figure 2.43:
13
C NMR spectrum of compound 2.29

105

Figure 2.44:
1
H NMR spectrum of compound 2.30

106

Figure 2.45:
13
C NMR spectrum of compound 2.30

107

Figure 2.46:
1
H NMR spectrum of compound 2.31

108

Figure 2.47:
13
C NMR spectrum of compound 2.31

109

Figure 2.48:
1
H NMR spectrum of compound 2.32

110

Figure 2.49:
13
C NMR spectrum of compound 2.32

111

Figure 2.50:
1
H NMR spectrum of compound 2.33

112

Figure 2.51:
13
C NMR spectrum of compound 2.33

113

Figure 2.52:
1
H NMR spectrum of compound 2.41

114

Figure 2.53:
13
C NMR spectrum of compound 2.41

115

Figure 2.54:
1
H NMR spectrum of compound 2.42

116

Figure 2.55:
13
C NMR spectrum of compound 2.42

117

Figure 2.56: 2D
1
H-
1
H COSY NMR spectrum of compound 2.42

118

Figure 2.57:
1
H NMR spectrum of compound 2.43

119

Figure 2.58:
13
C NMR spectrum of compound 2.43

120

Figure 2.59: 2D
1
H-
1
H COSY NMR spectrum of compound 2.43

121

Chapter 3: Total Synthesis of epoxy lipid mediators
3.1 Introduction
Many DHA-derived lipid mediators are envisioned to be formed through the formation of
epoxide intermediates, but it has never been confirmed experimentally. Thus, the synthesis of the
postulated epoxide intermediates is highly desirable for the final confirmation of the proposed
biosynthetic pathways. In the current work 3 different epoxide lipid compounds were synthesized,
two of which – (7R, 8R) and (13S, 14S) - are likely precursors of maresin 1 lipid mediator. Total
synthesis of the (7R, 8R) – epoxide was successfully accomplished in the current dissertation work.

Scheme 3.1. (7R, 8R) – Epoxide that was successfully synthesized in the current work
Protection D1 (PD1) was first discovered
32
in the context of its release from DHA in the brain
cells undergoing ischemia-reperfusion injury. NPD1 was shown to protect brain cells from
apoptosis by up-regulating anti-apoptotic proteins (Bcl-2, BclXl) and downregulating pro-
apoptotic ones (Bax and Bad). It also inhibits caspase-3 activation and IL-1beta-stimulated
expression of COX-2. Thus, it was initially discovered that NPD-1 protects brain cells from
oxidative stress related apoptosis. After the initial discovery NPD-1 was shown to be produced
widely in the body, not only in the brain, so the suffix “neuro-” started to be used mostly while
speaking about its expression and effects in the brain, otherwise the suffix is dropped. So the name
“protectin D1 (PD1)” is the identical compound to NPD1 but produced in other parts of the body,
but not in the brain. PD-1 was shown to have a number interesting effects in research publications.
For instance, it was shown that PD-1 inhibits replication of influenza-A viruses via RNA-transport
machinery and improves severe influenza
33
. Influenza-A is the common type of influenza and is
122

also the major source of mortality among influenza types. Thus, PD-1 can be of great importance
for the development of future anti-viral therapy against influenza-A viruses. NPD-1 has also been
shown to be of importance for retina cells survival protecting them from oxidative stress related
death
34
and in Alzheimer’s’ disease downregulating inflammatory signaling.
35

The simplified biosynthetic pathway of NPD1 formation is shown on Scheme 3.2 below.

Scheme 3.2. Simplified biosynthetic pathway for the formation of PD1/NPD1 from DHA
DHA 1 is converted to peroxide 2 by 15-lipoxygenase (15-LO). Further dehydration is supposed
to lead to epoxide 3 which is then converted to PD1/NPD1 4. Since it is not experimentally proved
that the formation of the PD1 occurs through the epoxide intermediate 3 and it is quickly
metabolized in vivo not allowing its separation and characterization, it was synthesized in the
current work to further the elucidation of the biosynthetic pathway.

123

A new pro-resolving pathway has recently been discovered leading to the production of potent
anti-inflammatory molecules named maresins (macrophage mediator in resolving inflammation).
Maresin1 was shown to have potent anti-inflammatory and pro-resolving properties in models of
zymosan-induced mouse peritonitis.
36

Scheme 3.3. (13S,14S)-epoxy maresin intermediacy in the production of Mar1

The proposed biochemical pathway leading to maresin1 (Scheme 3.3) involves two key steps:
Convertion of DHA to 14S-hydro(peroxy)-4Z,7Z,10Z,12E,16Z,19Z-DHA (14S-HpDHA) and then
to 13S,14S-epoxy-maresin by human macrophage lipoxygenase (hm12-LOX). Further enzymatic
hydrolysis leads to Mar1.

124

13S,14S-epoxy-maresin was shown to have its own intrinsic biochemical properties (Scheme
3.4). It inhibited leukotriene LTA4H limiting the production of pro-inflammatory LTB4. Human
LOX-12 AA lipoxygenation leading to the production of 12-hydroxy-5Z,8Z,10E,14Z-
eicosatetraenoic acid (12-HETE) that is involved in metastasis of cancer tumors
38
is also inhibited
but DHA lipoxygenation is not thus selectively shifting biochemistry towards the formation of
anti-inflammatory lipid mediators (LM). 13S,14S-epoxy-maresin upon incubation with human
macrophages of type 1 (M1) induced their phenotypic change to macrophages of type 2 (M2)
which gave higher levels of maresin1 then M1-phenotype further amplifying the anti-inflammatory
effects of the compound.
38

Scheme 3.4. Inhibitory pathways of 13S,14S-epoxy Maresin

125

3.2 Results
3.2.1 Retrosynthetic Analysis of the 7R, 8R-epoxide
The target compound has two conjugated (E)-double bonds next to the epoxide moiety
followed by (Z)-double bond, which immediately proposed us to use two key reactions for
achieving the desired stereochemistry. First, in our retrosynthetic analysis we cut the molecule on
the (Z)-double bond (Scheme 3.5) in hope that we can use Wittig reaction
39
with unstabilized ylide
3.11 and the conjugated aldehyde 3.10. Second, the aldehyde 3.10 can be constructed from the
respective 3.9 in one step by the Wittig reaction with stabilized
(Triphenylphosphoranylidene)acetaldehyde (PPh3CHCHO) reagent
14
achieving the desired
conjugated two (E)-double bond configuration.

Scheme 3.5. Retrosynthetic scheme of methyl (Z)-6-((2R,3R)-3-((1E,3E,5Z,8Z,11Z)-
tetradeca-1,3,5,8,11-pentaen-1-yl)oxiran-2-yl)hex-4-enoate
126

The configuration of 3 other (Z)-double bonds is achieved by the Lindlar hydrogenation
13
.
The remaining (R, R) configuration is established by starting from the (E)-4-bromobut-2-enoate
and then Sharpless epoxidation
40
of this (E)-bond on the later stage.

3.2.2 Synthesis of Building Blocks of the 7R, 8R-epoxide
The synthesis of key intermediate 4.10 is presented on Scheme 3.6 below.

Scheme 3.6. Synthesis of key intermediate 3.10. (a) LiAlH4, AlCl3, Et2O, -78 ⁰C, 33%; (b) CuI,
NaI, K2CO3, DMF, 32%; (c) H2/Lindlar cat., quinoline, EtOAc, 80%; (d) (-)-DET, Ti(OiPr)4, t-
BuOOH, 4Å MS, -40 ⁰C, 95%; (e) DMP, Py, DCM, 67%; (f) Ph3PCHCHO, Toluene, 95 ⁰C, 36%.
The synthesis starts from the reduction of (E)-4-bromobut-2-enoate by LiAlH4 with AlCl3
catalyst in ether (a)
41
. The reaction proceeds with low to moderate yield possibly due to side
reaction of LiAlH4 reduction of the bromine in the allylic position. Also, the fact that the starting
technical grade (E)-4-bromobut-2-enoate is not clean enough most probably affecting both the
reduction and the following copper-catalyzed coupling. The obtained compound 3.1 is then
127

introduced to copper-catalyzed coupling (b) with pentynoic methyl ester followed by the Lindlar
hydrogenation
13
which establishes (Z)-stereochemistry at the (4,5)-double bond of 3.4. Sharpless
epoxidation
40
of 3.4 with D-(-)-diethyl tartrate gives compound 3.8 establishing (R, R)-
stereochemistry of the epoxide ring. Subsequent Dess-Martin oxidation
17
of the alcohol group next
to the epoxide ring gives 3.9 in 67% yield. It should be noted that Dess-Martin reaction was done
in the open air and with the addition of a drop of water which speeds the reaction up and improves
the yields. Subsequent Wittig reaction
14
with stabilized (triphenylphosphoranylidene)
acetaldehyde (PPh3CHCHO) gives first the product of single chain-homologation in 1-2 hours
which is clearly observed by TLC monitoring and
1
H – NMR spectra and then completes up slowly
in the next 5-6 hours. The reaction is very critical and should be carefully monitored. TLC itself
can be very misleading giving the impression of the large presence of the product of single
homologation reaction even after 7-8 hours. The reaction should be nonetheless quenched and
purified. Otherwise, letting the reaction run for longer leads only to the destruction/further
undesired homologation of the product without increasing the yield.

128

Synthesis of the Wittig salt 3.11 is shown on the Scheme 3.7 below.

Scheme 3.7. Synthesis of key intermediate – Wittig salt 3.11. (a) CuI, NaI, K2CO3, DMF, 98%;
(b) H2/Lindlar cat., quinoline, EtOAc, 67%; (c) TsCl, Et3N, r.t., overnight, 96%; (d) NaI, acetone,
reflux, 2h, 82%; (e) PPh3, toluene, reflux, overnight, 90%.
The synthetic route starts with copper-catalyzed coupling (a) of 1-bromo-2-pentyne with
butyne-1-ol giving compound 3.2. Following Lindlar hydrogenation (b)
13
installs two (Z)-bonds
in one step. The reaction tend to go better under more dilute conditions, so adding additional ethyl
acetate during the reaction can possibly be done. Sufficient amount of quinolone is very critical,
especially on larger than 100mg reaction scale. The reaction can fail and/or go very slow if not
enough quinolone is present (0.1ml per 100mg tends to be enough). Subsequent tosylation (c)-
iodide substitution reactions (d) gave the idodide 3.7. The last step on the scheme (e) should be
done under very strict unhydrous conditions and without purification (to avoid contamination with
water) dried under P2O5 which is very critical for the success on the very last Wittig reaction step
25
.

129

After successfully obtaining Wittig salt 3.11 and the conjugated epoxide 3.10, they were
introduced to the Wittig reaction with NaHMDS in THF
42
(Later, in our lab better conditions were
found that utilize KHMDS
25
) which is shown on the Scheme 3.8 below.

Scheme 3.8. Synthesis of the final (7R, 8R)-epoxy methyl ester 3.12.
The product 3.12 was purified on silica column loaded with small amount of Et3N and
stored under low temperature in the deep freezer with some amount Et3N present to avoid he
destruction. It should be noted that 3.12 is unstable and get gradually degraded under room
temperature which requires special handling
42
.

130

3.2.3 Retrosynthetic Analysis of the 16S, 17S-epoxy Protectin
The retrosynthetic analysis of the 16S, 17S-epoxy protectin that is supposed to be
involved in the biosynthesis of PD1/NPD1 is presented on Scheme 3.9.

Scheme 3.9. Retrosynthetic analysis of 16S, 17S-epoxy protectin
The target compound 3.21 was split in retrosynthetic analysis on 11,12 – cis double bond
which was selected to be constructed by the Wittig reaction
39,42
with unstabilized ylide 3.20 and
the aldehyde 3.17. Synthesis of the compound of the Wittig salt 3.20 was accomplished by Stephen
Glynn
26
and involved the improved procedure of the synthesis of the compound 3.18 which is
followed by copper-catalyzed coupling yielding 3.19. Two cis-double bond configuration was
established by Lindlar hydrogenation
13
and the alcohol group of 3.19 was converted to the iodide
131

producing Wittig salt 3.20. Aldehyde 3.17 was envisaged to be synthesized by Wittig chain
elongation reaction from 3.16. The aldehyde was generated from the respective alcohol by Dess-
Martin oxidation
17
. The epoxide S, S – configuration was designed to be constructed by the
Sharpless asymmetric epoxidation
40
of the vinylic trans-double bond of the lithium aluminum
hydride reduction product of 3.13.
3.2.4 Synthesis of Building Blocks of the 16S, 17S-epoxy Protectin
The synthesis of key intermediate 3.17 is presented on the scheme 3.10 below.

Scheme 3.10. Synthesis of key intermediate – aldehyde 3.17. (a) CuI, NaI, K2CO3, DMF, 96%;
(b) LAH, Et2O, reflux, overnight, 81%; (c) (-)-DET, Ti(OiPr)4, t-BuOOH, 4Å MS, -40 ⁰C, 94%;
TsCl, Et3N, r.t., overnight, 96%; (d) H2/Lindlar cat., quinoline, EtOAc, then DMP, H2O, NaHCO3,
DCM, 75%; (f) Ph3PCHCHO, Toluene, 95 ⁰C, 51%.
1-Bromo-2-pentyne was reacted with propargyl alcohol yielding 3.13 which was later
reduced with aluminum hydride under reflux conditions in diethyl ether. The obtained trans-vinyl
alcohol 3.14 was then converted to (S, S) - epoxide 3.15 using stereospecific Sharpless epoxidation
reaction
40
with (-)-DET. The alkyne moiety of 3.15 was selectively hydrogenated to cis-double
bond and the alcohol oxidized by the Dess-Martin reagent
17
yielding compound 3.16. There was
no issues with the epoxide moiety upon Lindlar hydrogenation, so the epoxide is stable under the
conditions used.
132

Finally two key pieces: epoxide 3.17 and the Wittig salt 3.20 were coupled together by
Wittig reaction with KHMDS-base that was optimized by Stephen Glynn
25
, improving the yields
of the reaction (Scheme 3.11 below).

Scheme 3.11. Final Wittig coupling that establishes cis-stereochemistry at 10
th
position of 3.21.

133

3.2.5 Retrosynthetic Analysis of the 13S, 14S-epoxy Maresin
The key reaction that constructs the target compound was again selected to be the Wittig
coupling reaction (Scheme 3.12). The configuration of three cis-double bonds at 4
th
, 16
th
and 19
th

positions were constructed using Lindlar hydrogenation
13
.

Scheme 3.12. Retrosynthetic scheme of the 13S, 14S – epoxy maresin.
The epoxide configuration was established by the Sharpless epoxidation. Two trans-
double bonds were created by the Wittig homologation reaction with
(triphenylphosphoranylidene) acetaldehyde (PPh3CHCHO).

134

3.2.6 Synthesis of Building Blocks of the 13S, 14S-epoxy Maresin
The synthesis of the building block that contains epoxide group 3.29 starts with copper-
catalyzed coupling yielding alcohol 3.22 (Scheme 3.13 below, step a).

Scheme 3.13. Synthesis of the key epoxy aldehyde building block 3.29. (a) CuI, Na2CO3, Bu4NCl,
0 ⁰C, 85%; (b) LiAlH4, Et2O, reflux, then (c) MeOH, Na2CO3, 70% over two steps; (d) CuI, NaI,
K2CO3, DMF, 57%; (e) H2/Lindlar cat., quinoline, EtOAc, 92%; (f) (+)-DET, Ti(OiPr)4, t-
BuOOH, 4Å MS, -40 ⁰C, 98%; (g) DMP, H2O, NaHCO3, DCM, 50%; (h) Ph3PCHCHO, toluene,
95⁰C, 21%.
Regular copper-catalyzed conditions that we have always been previously using gave us low yields
in this particular case (step a): 30-40%. Looking in literature we found an alternative conditions
that utilize Bu4NCl reagent, avoids NaI usage and the set up occurs at 0 ⁰C, warming up slowly to
room temperature overnight
43
. The procedure is much more water sensitive due to hygroscopic
Bu4NCl reagent that should be handled carefully. It gave us way better yields that were reproduced
multiple times: 80-90%. Further LiAlH4 reduction in diethyl ether as a solvent gave us compound
135

3.23 that was deprotected further to 3.24. Further copper-catalyzed coupling (regular conditions
that we use), Lindlar hydrogenation and Sharpless epoxidation gave us alcohol 3.27, the alcohol
group of which was further oxidized with Dess-Martin reagent. It should be noted that Dess-Martin
oxidation on such substrates containing the epoxide group next to the alcohol never gave us higher
than 40-50% yield, not like with other substrates that do not contain epoxide which tend to give
75-95% yields. Further Wittig homologation should be done in toluene solvent at reflux conditions.
The yields in this case are a bit lower than in case of epoxy-protectin compound synthesis that was
discussed in the previous chapter. A characteristic difficult part of the reaction is that TLC can be
misleading and the reaction should be stopped no later than in 5-6h, even though TLC seemingly
show a plenty of mono-homologated compound being still present in the reaction mixture. The
prolongation of the reaction leads only to the reduction of the yields.
Another key building block – Wittig salt 3.37 – was synthesized in the following way
(Scheme 3.14) and started with the protection of carboxylic functionality of pentynoic acid and
subsequent nucleophilic substitution reaction of the generated acetylide with 2-(2-
iodoethoxy)tetrahydro-2H-pyran:

Scheme 3.14. Synthesis of key Wittig salt 3.37. (a) DCC, DMAP, DCM, (3-methyl-3-oxetanyl)-
methanol, 75%; (b) BF3∙OEt2, DCM, 78%; (c) n-BuLi, HMPA, 2-(2-iodoethoxy)tetrahydro-2H-
pyran, THF, 85%; (d) HCl, THF/H2O, 86%; (e) MeOH, Et3N, 87%; (f) H2/Lindlar cat., quinoline,
136

EtOAc, 88%; (g) TsCl, Et3N, DCM, 98%; (h) NaI, acetone, reflux, 98%; (i) PPh3, toluene, reflux,
92%.
Further deprotection was done with HCl and carboxylic methyl ester was generated by the
reaction with methanol under basic conditions yielding 3.33. Then, triple bond was hydrogenated
under Lindlar conditions
13
furnishing 3.34, alcohol functionality of which was further converted
to iodide 3.36. Reaction with triphenylphosphine in toluene under reflux conditions yielded Wittig
salt 3.37 that was dried with P2O5, the night before the final Wittig coupling reaction presented on
Scheme 3.15 below.

Scheme 3.15. Final KHMDS-mediated coupling that generates 13S, 14S-epoxy maresin
The reaction was first successfully accomplished by Min Zhu
42
, and then improved by
switching the base from NaHMDS to KHMDS by Stephen Glynn
25
.

3.3 Conclusion
The total stereochemical synthesis of three DHA-derived epoxy lipid mediators were
developed and successfully completed: epoxy-maresin (13S, 14S), epoxy-protectin (16S, 17S) and
(7R, 8R)-epoxide were accomplished in good overall yields. As a result of epoxy-maresin
biological investigations done by our collaborator Prof. Serhan’s group, and was published in
FASEB journal
44
.
137

3.4 Experimental Procedures
All reactions, unless otherwise noted, were carried in flame dried flasks under argon
atmosphere. Dried and concentrated refers to removal of residual water with anhydrous MgSO4,
followed by evaporation of the solvent on the rotary evaporator. THF was freshly distilled from
sodium-benzophenone, benzene and dichloromethane from CaH2 and anhydrous DMF, EtOH, and
MeOH were purchased from commercial sources.
1
H and
13
C NMR spectra were recorded on a
Varian Mercury 400 or 600 MHz using residual
1
H or
13
C signals of deuterated solvents as internal
standards. UV spectra were recorded on a Hewlett-Packard 8350 instrument. HPLC analyses were
performed on a Rainin dual pump HPLC system equipped with a Phenomenex ODS column and
an UV-VIS detector.

3.1
(E)-4-bromobut-2-en-1-ol (3.1): To a stirred suspension of LiAlH4 (19.6ml (1M), 19.6
mmol) in dry Et2O (140 mL) was carefully added AlCl3 (0.87 g, 6.5 mmol) in small portions at 0
°C. The mixture was cooled to -78 °C, and a solution of 3.2g (16.3mmol) of 85% clean tech-grade
methyl (E)-4-bromobut-2-enoate in dry Et2O (8 mL) was added over a period of 20 min. After
additional 3 h at - 78 °C, the reaction mixture was carefully quenched with a 10% H2SO4 (10 mL).
The reaction mixture was worked up with saturated solution of ammonium chloride and extracted
with diethyl ether. The organic extract was dried (Na2SO4) and concentrated to afford 0.8g (33%
yield) of the crude alcohol 3.1 which was used for the next step.
1
H NMR (400MHz, CDCl3)

3.2
Nona-3,6-diyn-1-ol (3.2): 3-butyn-1-ol (4.2g, 28.6mmol) and 1-bromo-2-pentyne (1.0g ,
14.3mmol) were mixed and dissolved in 6ml anhydrous DMF. CuI (5.4g, 28.4mmol), NaI (4.3g,
28.7mmol) and K2CO3 (3.9g, 28.2mmol) were added and the solution was stirred overnight in
dark. The reaction mixture was worked up with NH4Cl aqueous solution and extracted with ether.
After removing the solvent the mixture was purified on a silica column with 25% EtOAc/hexanes
138

to afford the product (1.94g, 98%).
1
H NMR (400MHz, CDCl3) 3.70 (t, J = 6.2 Hz, 2H), 3.13 (p,
J = 2.4 Hz, 2H), 2.44 (tt, J = 6.2, 2.4 Hz, 2H), 2.17 (qt, J = 7.5, 2.4 Hz, 2H), 1.11 (t, J = 7.5 Hz,
3H).
13
C NMR (400MHz, CDCl3) 82.27, 76.95, 76.84, 73.51, 61.25, 23.28, 13.99, 12.51, 9.87.

3.3
Methyl-(Z)-9-hydroxynon-4-en-7-ynoate (3.3): The same procedure as for compound
3.2 was followed with 4-Pentynoic acid methyl ester (1.2g, 10.7mmol) and 1.0g (14.3mmol) of
3.1 was used. The reaction furnished 0.3g (yield - 32%) of the product 3.3 which was obtained
after purification with 35% EtOAc/hexanes.
1
H NMR (400MHz, CDCl3) 5.90 (dtt, J = 15.1, 5.7,
1.8 Hz, 1H), 5.68 (dtt, J = 15.2, 5.3, 1.4 Hz, 1H), 4.17-4.11 (m, 2H), 3.70 (s, 3H), 2.95-2.89 (m,
2H), 2.56-2.47 (m, 5H).
13
C NMR (400MHz, CDCl3) 172.69, 130.58, 127.07, 63.39, 51.91, 33.89,
21.83, 14.92.

3.4
Methyl (4Z,7Z)-9-hydroxynona-4,7-dienoate (3.4): 0.05g (0.27 mmol) of 3.3 was
dissolved in 40ml of ethyl acetate. 0.1ml of quinolone, and 0.02g of Lindlar catalyst were added.
The reaction mixture was purged with hydrogen and carefully monitored by the TLC
(10%EtOAc/hexanes). After the reaction completion the mixture was filtered, solvent removed
and purification was done with 25%EtOAc/hexanes on a silica column yielding 0.04g (80%) of
the product 3.4.
1
H NMR (400MHz, CDCl3) 5.71- 5.64 (m, 2H), 5.48-5.38 (m, 2H), 4.17-4.02 (m,
2H), 3.67 (s, 3H), 2.86-2.78 (m, 2H), 2.39-2.35(m, 5H).
13
C NMR (400MHz, CDCl3) 173.72,
131.05, 129.63, 128.90, 128.39, 63.82, 51.74, 34.14, 30.08, 22.90.

3.5
(3Z,6Z)-nona-3,6-dien-1-ol (3.5): The same procedure as for compound 3.4 (look above)
was followed. 0.15g (1.1mmol) of compound 3.3 was used and 0.10g (67%) of the product 3.5
139

was obtained after purification with 15% EtOAc/hexanes solvent.
1
H NMR (400MHz, CDCl3)
5.62-5.49 (m, 1H), 5.46-5.34 (m, 2H), 5.34-5.26 (m, 1H), 3.66 (q, J = 6.3 Hz, 2H), 2.82 (t, J = 7.2
Hz, 2H), 2.41-2.30 (m, 2H), 2.14-2.02 (m, 2H), 1.43-1.34 (m, 1H), 0.97 (t, J = 7.5 Hz, 3H).
13
C
NMR (400MHz, CDCl3) 132.34, 131.72, 126.99, 125.47, 62.40, 30.95, 25.81, 20.73, 14.39.

3.6
(3Z,6Z)-nona-3,6-dien-1-yl 4-methylbenzenesulfonate (3.6): 0.05g (0.36mmol) of
alcohol 3.5 was dissolved in 0.8 ml DCM. To the flask 0.18ml triethylamine (0.16 mmol) and 0.1g
of p-toluenesulfonyl chloride were added sequentially and the reaction was stirred overnight at
room temperature. The solvent was removed and the reaction mixture was purified on a silica
column with 15% EtOAc/hexanes to afford 0.11g of tosylate 3.6 in 96% yield.
1
H NMR (400MHz,
CDCl3) 7.81-7.77 (m, 2H), 7.36-7.32 (m, 2H), 5.51-5.43 (m, 1H), 5.42-5.33 (m, 1H), 5.28-5.19
(m, 2H), 4.02 (t, J = 7.0 Hz, 3H), 2.72 (ttt, J = 7.3, 1.6, 0.7 Hz, 2H), 2.44-2.39 (m, 2H), 2.07-1.98
(m, 2H), 0.95 (t, J = 7.5 Hz, 1H).
13
C NMR (400MHz, CDCl3) 144.84, 133.36, 132.52, 132.21,
129.95, 128.06, 126.52, 123.11, 69.77, 27.25, 25.72, 21.79, 20.69, 14.36.

3.7
(3Z,6Z)-1-iodonona-3,6-diene (3.7): 50ml round bottom flask with 0.03g of molecular
sieve powder inside was flame-dried. In the flask 0.1g (0.34mmol) of tosylate 3.6 was dissolved
in 3 ml of anhydrous acetone, and then 0.13g (0.85mmol) of NaI and 0.09g (0.67mmol) of K2CO3
were added. The reaction was refluxed for 2 hours and worked up with saturated Na2S2O3 aqueous
solution, and extracted with ether. After removing the solvent on a rotary evaporator the mixture
was purified on a silica column with pure pentanes solvent to afford product 3.7 in 82% yield
(0.07g).
1
H NMR (400MHz, CDCl3) 5.58-5.47 (m, 1H), 5.46-5.24 (m, 3H), 3.15 (t, J = 7.3 Hz,
2H), 2.78 (t, J = 7.2 Hz, 2H), 2.66 (q, J = 7.3 Hz, 2H), 2.13-1.98 (m, 2H), 0.98 (t, J = 7.5 Hz, 1H).
13
C NMR (400MHz, CDCl3) 132.48, 130.95, 128.20, 126.69, 31.65, 25.88, 20.75, 14.40, 5.37.

140

3.8
Methyl (Z)-6-((2S,3R)-3-(hydroxymethyl)oxiran-2-yl)hex-4-enoate (3.8): Flame-dry a
10 ml flask with 25mg 4Å molecular sieve powder in it and add 1 ml of DCM. The flask was
cooled down to -20⁰C and 0.02ml of (-)-Diethyl tartrate, 0.03ml of Ti(O-iPr)4 and 0.20ml of 5M
solution (1.0mmol) of t-BuOOH were added sequentially. After stirring for 1 hour 0.03g
(0.16mmol) of alcohol 3.4 dissolved in 1 ml (0.5ml, then again 0.5ml) DCM was cannulated into
the solution and the reaction stirred further for 3 hours. The reaction mixture was filtered, DCM
removed, and the mixture was purified on a silica column with 50% EtOAc/hexanes to afford
product 3.8 (0.03g, 94%).
1
H NMR (400MHz, CDCl3) 5.56-5.42 (m, 2H), 3.90 (ddd, J = 12.6, 5.3,
2.7 Hz, 1H), 3.71-3.60 (m, 4H), 3.01 (td, J = 5.3, 2.3 Hz, 1H), 2.97 (dt, J = 4.7, 2.4 Hz, 1H), 2.43-
2.33 (m, 6H), 1.64 (dd, J = 7.4, 5.5 Hz, 1H).
13
C NMR (400MHz, CDCl3) 173.60, 130.95, 124.84,
61.70, 57.96, 55.16, 51.75, 33.98, 29.35, 23.03.

3.9
Methyl (Z)-6-((2S,3S)-3-formyloxiran-2-yl)hex-4-enoate (3.9): Alcohol 3.4 (0.055 g,
0.28 mmol) was dissolved in 5 ml DCM, then 0.24 g Dess-Martin periodinane and 0.24 g NaHCO3
were added and the slurry solution was stirred for 1 hour. The reaction was worked up with 1:1
NaHCO3/Na2S2O3 saturate solution and extracted 3 times (20ml) with DCM. DCM was removed
on the rotary evaporator and the mixture was purified on a silica column with 20% EtOAc/hexanes
to afford the aldehyde 3.9 (0.036g, 67%).
1
H NMR (400MHz, CDCl3) 9.03 (d, J = 6.2 Hz, 1H),
5.59-5.53 (m, 1H), 5.46-5.39 (m, 1H), 3.68 (s, 3H), 3.29 (td, J = 5.1, 1.9 Hz, 1H), 3.18 (dd, J =
6.2, 1.9 Hz, 1H), 2.51 (ddt, J = 7.4, 5.0, 1.2 Hz, 2H), 2.42-2.34 (m, 5H).
13
C NMR (400MHz,
CDCl3) 198.33, 173.43, 132.12, 123.38, 58.60, 55.98, 51.79, 33.79, 28.85, 23.01.

3.10
141

Methyl (Z)-6-((2S,3R)-3-((1E,3E)-5-oxopenta-1,3-dien-1-yl)oxiran-2-yl)hex-4-enoate
(3.10): 0.036g (0.18mmol) of Aldehyde 3.9 and 0.083g (0.27mmol)
(triphenylphosphoranylidene)acetaldehyde were dissolved in 0.8ml of toluene and refluxed for 2h.
The (triphenylphosphoranylidene)acetaldehyde was added again (0.028g, 0.09mmol), and then
again in the same amount (0.028g, 0.09mmol) after 2h. TLC (20% EtOAc/Hexanes) showed
completion, the reaction mixture was dried down on a rotary evaporator and the remaining fraction
was purified on column with 20%EtOAc/hexanes solvent (500ml), then switching to
30%EtOAc/hexanes (300ml) yielding aldehyde 3.10 (0.016g, 36%).
1
H NMR (600MHz, CDCl3)
9.58 (d, J = 7.9 Hz, 1H), 7.08 (dd, J = 15.7, 10.7 Hz, 1H), 6.64 (dd, J = 15.3, 10.9 Hz, 1H), 6.17
(dd, J = 15.4, 7.9 Hz, 1H), 5.98 (dd, J = 15.3, 7.4 Hz, 1H), 5.57-5.50 (m, 1H), 5.49-5.43 (m, 1H),
3.68 (s, 3H), 3.27 (dd, J = 7.5, 2.1 Hz, 1H), 2.96 (td, J = 5.3, 2.1 Hz, 1H), 2.47-2.42 (m, 2H), 2.41-
2.36 (m, 4H).
13
C NMR (600MHz, CDCl3) 193.67, 173.52, 150.05, 141.21, 132.37, 131.36,
131.14, 124.32, 60.73, 56.88, 51.76, 33.93, 29.71, 23.05.

3.11
((3Z,6Z)-nona-3,6-dien-1-yl)triphenylphosphonium iodide (3.11): Iodide 3.7 (0.07g,
0.28mmol) was dissolved in 0.5ml toluene and PPh3 (0.117 g, 0.45 mmol) was added. The reaction
mixture was refluxed overnight, and then, after removing toluene under vacuum, the residue was
dissolved in 0.5ml MeOH and transferred to a 15 ml plastic centrifuge tube. 5ml of pentane was
added and the mixture was shaken violently and then centrifuged for 5min. The supernatant
solution was taken up using a Pasteur pipet and another 5ml of pentane was added. The cycle was
repeated for another 10-15 times until no PPh3 can be detected in the supernatant by TLC. The
solvent was removed affording product 3.11 as thick colorless oil (0.13 g, 90%).
1
H NMR
(400MHz, CDCl3) 7.90-7.77 (m, 9H), 7.74-7.67 (m, 6H), 5.61 (dtt, J = 10.5, 7.2, 1.6 Hz, 1H),
5.45-5.36 (m, 1H), 5.36-5.29 (m, 1H), 5.17-5.09 (m, 1H), 3.89-3.80 (m, 2H), 2.58-2.52 (m, 2H),
2.53-2.43 (m, 2H), 1.93-1.84 (m, 2H). 0.88 (t, J = 7.1 Hz, 1H).
13
C NMR (400MHz, CDCl3)
135.28, 135.25, 134.00, 133.90, 132.54, 130.74, 130.61, 126.29, 118.72, 117.87, 25.69, 23.85,
20.70, 14.33.
142

3.12
Methyl (Z)-6-((2R,3R)-3-((1E,3E,5Z,8Z,11Z)-tetradeca-1,3,5,8,11-pentaen-1-
yl)oxiran-2-yl)hex-4-enoate (3.12): Phosphonium salt 3.11 (0.033g, 0.06mmol) was dried under
vacuum and P2O5 overnight. Under Argon atmosphere, the phosphonium salt was dissolved in
0.2ml anhydrous THF and cooled to -78 ºC. NaHMDS (0.06ml, 0.06mmol) in 1.0 M THF solution
was added dropwise and the reaction was stirred for 30 minutes and warmed to 0 ºC for 20 minutes,
during which a bright orange color solution was produced. The reaction mixture was cooled to -
78 ºC again and aldehyde 3.10 was cannulated in (8mg, 0.03mmol) three times: with 0.2ml, 0.1ml,
0.1ml of anhydrous THF and the reaction was stirred for 1h. The solvent was quickly removed
under vacuum and the mixture was purified on a silica column with 5% EtOAc/5% Et3N/hexanes
eluent to afford the product (3 mg, 38%). Product was stored at -78ºC in benzene with 1% Et3N.
UV: λmax = 280nm (in hexane).
1
H NMR (600MHz, CDCl3) 6.63 (dd, J = 14.8, 11.2 Hz, 1H),
6.47 (dd, J = 15.2, 10.8 Hz, 1H), 6.27-6.07 (m, 2H), 5.60-5.39 (m, 6H), 3.43 (s, 3H), 3.12 (dd, J =
7.7, 1.9 Hz, 1H), 3.03 (t, J = 7.1 Hz, 2H), 2.94-2.86 (m, 2H), 2.79 (td, J = 5.2, 2.1 Hz, 1H), 2.38-
2.26 (m, 4H), 2.26-2.19 (m, 2H), 2.15-2.05 (m, 2H).
13
C NMR (600MHz, CDCl3) 172.70, 134.13,
132.38, 132.28, 131.38, 131.13, 130.92, 129.33, 129.15, 127.33, 125.26, 60.08, 57.68, 51.04,
34.99, 30.24, 25.98, 25.66, 23.20, 20.96, 14.47.

3.13
Octa-2,5-diynol (3.13): (See compound 2.26 in chapter 2).

143

3.14
(E)-Oct-2-en-5-ynol (3.14): (See compound 2.27 in chapter 2).

3.15
((2S,3S)-3-(pent-2-yn-1-yl)oxiran-2-yl)methanol (3.15): Flame-dry a 10 ml flask with
25mg 4Å molecular sieve powder in it and add 1 ml of DCM. The flask was cooled down to -
20⁰C and 0.01ml of (-)-DET, 0.02ml of Ti(O-iPr)4 and 0.25ml of 5M solution (1.0mmol) of t-
BuOOH were added sequentially. After stirring for 1 hour 0.04g (0.3mmol) of alcohol 3.14
dissolved in 1 ml (0.5ml, then again 0.5ml) DCM was cannulated into the solution and the
reaction stirred further for 3 hours. The reaction mixture was filtered, DCM removed, and the
mixture was purified on a silica column with 50% EtOAc/hexanes to afford product 3.8 (0.045g,
98%).
1
H NMR (500 MHz, Chloroform-d) δ 4.00 – 3.91 (m, 1H), 3.74 – 3.62 (m, 1H), 3.16 –
3.09 (m, 2H), 2.66 – 2.56 (m, 1H), 2.54 – 2.45 (m, 1H), 2.21 – 2.12 (m, 2H), 1.12 (t, J = 7.5 Hz,
3H).
13
C NMR (126 MHz, cdcl3) δ 84.42, 77.37, 73.41, 72.12, 62.67, 61.32, 57.88, 53.69.

3.16
(2R,3S)-3-((Z)-pent-2-en-1-yl)oxirane-2-carbaldehyde (3.16): Compound 3.15 (0.045g,
0.32 mmol) was dissolved in 20ml of EtOAc, and 0.05ml of quinoline and 20mg of Lindlar catalyst
were added. The reaction mixture was purged with hydrogen and monitored by TLC. After the
completion, the reaction mixture was filtered out, solvent removed and the remaining fraction was
dissolved in 20ml of regular dichloromethane. Then ~1g of NaHCO3 and 0.1g (0.24mmol) of Dess-
144

Martin periodinane were added together with a drop of tap water. After 1h the reaction mixture
showed completion by TLC and was worked up with 50ml of sodium thiosulfate-sodium
bicarbonate solution, extracted with dichloromethane (4x30ml) and dried over sodium sulfate.
Sodium sulfate was filtered out, solvent removed and the remaining mixture was purified on a
column with 5% EtOAc/hexanes yielding 0.15g (0.39mmol, 88%) of the aldehyde 3.16.
1
H NMR
(500 MHz, Chloroform-d) δ 9.03 (d, J = 6.2 Hz, 1H), 5.65 – 5.55 (m, 1H), 5.36 – 5.28 (m, 1H),
3.30 – 3.24 (m, 1H), 3.20 – 3.14 (m, 1H), 2.54 – 2.36 (m, 2H), 2.10 – 1.99 (m, 2H), 0.98 (t, J =
7.5 Hz, 3H).
13
C NMR (126 MHz, cdcl3) δ 198.45, 136.27, 120.95, 58.70, 56.18, 28.80, 20.87,
14.23.

3.17
(2E,4E)-5-((2S,3S)-3-((Z)-pent-2-en-1-yl)oxiran-2-yl)penta-2,4-dienal (3.17): The
reaction should not be done over 4h which leads to gradual deterioration of the reaction yields.
To 10ml pear-shaped flame-dried flask 0.21g (1.5mmol) of aldehyde 3.16 and 0.5g (1.6mmol)
(triphenylphosphoranylidene) acetaldehyde were dissolved in 0.8ml of toluene and refluxed for
2h. Then (triphenylphosphoranylidene)acetaldehyde was added again (0.2g, 0.6mmol). After 2h
more TLC (20% EtOAc/Hexanes) showed completion, the reaction mixture was dried down on a
rotary evaporator and the remaining fraction was purified on column with 20%EtOAc/hexanes
solvent (500ml), then switching to 30%EtOAc/hexanes (300ml). After the purification, 0.09g
(0.6mmol) of unreacted aldehyde 3.16 was recovered and clean product 3.17 (0.08g, 0.4mmol,
49%).
1
H NMR (400 MHz, Chloroform-d) δ 9.58 (d, J = 7.9 Hz, 1H), 7.08 (dd, J = 15.4, 11.0 Hz,
1H), 6.63 (dd, J = 15.3, 11.0 Hz, 1H), 6.17 (dd, J = 15.4, 7.9 Hz, 1H), 5.99 (dd, J = 15.3, 7.4 Hz,
1H), 5.68 – 5.49 (m, 1H), 5.45 – 5.29 (m, 1H), 3.28 – 3.22 (m, 1H), 2.95 (td, J = 5.3, 2.0 Hz, 1H),
2.52 – 2.30 (m, 2H), 2.12 – 2.00 (m, 2H).
13
C NMR (101 MHz, cdcl3) δ 193.67, 150.09, 141.37,
135.52, 132.33, 131.04, 121.89, 60.98, 56.93, 31.75, 22.82, 14.28.

145

3.21

Methyl (4Z,7Z,10Z,12E,14E)-15-((2R,3R)-3-((Z)-pent-2-en-1-yl)oxiran-2-
yl)pentadeca-4,7,10,12,14-pentaenoate (3.21): The phosphonium salt 3.20 (178mg, 0.312
mmols) was dried under vacuum and P2O5 in the reaction flask overnight. 1.5 mL of still dried
THF was added and the mixture was then cooled to -78°C. To the reaction mixture a 1M KHMDS
solution (58 mg, 0.288 mmols) was added dropwise via syringe over 10 min the reaction was then
allowed to stir at 0°C for 20 min, then rt for 10 min until the reaction became an red/orange/brown
color. The reaction mixture was then cooled to -78°C and the aldehyde 3.17 (30 mg, 0.16 mmols)
was added dropwise via syringe over 10 min, the reaction was allowed to slowly warm to rt and
stirred for 1 h. The reaction mixture was directly subjected to purification without workup or
removal of solvent. The crude reaction mixture was purified on silica gel using NEt3-EtOAc-
hexanes (5% - 5% - 90%) as the eluent to afford the cis-selective Wittig product (6.1) (50 mg,
88%) as yellow colored oil store in NEt3-benzene (1%).
1
H NMR (400 MHz, Benzene-d6) 6.38
(m, 2H), 6.06 (m, 2H), 5.34 (m, 8H), 3.41 (m, 3H), 3.14 (tt, J = 7.7, 2.6 Hz, 1H), 3.01 (ddd, J =
7.3, 5.4, 1.7 Hz, 1H), 2.89 (dddt, J = 7.3, 4.1, 1.7, 0.8 Hz, 1H), 2.80 (dtt, J = 9.5, 4.3, 1.7 Hz, 1H),
2.34 (m, 1H), 2.11 (m, 5H), 1.95 (m, 2H), 1.22 (m, 2H), 0.98 (t, J = 7.5 Hz, 3H).
13
C NMR (400
MHz, c6d6) 172.76, 134.67, 134.18, 132.38, 131.42, 131.09, 129.33, 129.16, 128.95, 128.83,
128.54, 127.92, 123.22, 60.26, 57.75, 51.08, 34.02, 30.11, 26.62, 25.99, 23.17, 21.01, 14.41.

146

3.22
6-(trimethylsilyl)hexa-2,5-diyn-1-ol (3.22): To a 100ml flame-dried flask under nitrogen
in the glove box 3.2g of Bu4NCl (11.5 mmol), 1.7g of Na2CO3 (16.0 mmol) and 2.2g of CuI (11.5
mmol) were transferred. The flask was filled with argon and 5ml of anhydrous DMF was added.
The reaction mixture was cooled down to 0 ⁰C with ice bath and 0.7ml of propargyl alcohol (12.2
mmol) followed by 1.7ml of (3-bromoprop-1-yn-1-yl)trimethylsilane (10.4 mmol) were added.
The reaction mixture was covered with aluminum foil and stirred overnight. The reaction mistured
was worked up with saturated ammonium chloride solution and extracted with diethyl ether
8x30ml. The extract was washed one time with 300ml of saturated ammonium chloride solution,
ether removed on the rotary evaporator and the resulting oily mixture was purified on silica column
using 20% of EtOAc in hexanes which yielded 1.5g (87 %) of the alcohol 3.22.
1
H NMR (400
MHz, CDCl3) 4.25 (m, 2H), 3.25 (m, 2H), 0.15 (s, 9H).
13
C NMR (400 MHz, CDCl3) 99.5, 85.6,
79.8, 79.0, 51.4, 11.1, 0.01.

3.24
(E)-hex-2-en-5-yn-1-ol (3.24): Transfer 6 ml of 1.0M diethyl ether solution of LiAlH4 into
a 50ml flame-dried flask under argon and cool it to 0 ⁰C. Cannulate 1.0g (6.0mmol) of alcohol 3.22
in 3ml diethyl ether into the solution and let the reaction warm up to r.t., then reflux overnight.
Work up with NH4Cl aqueous solution and extract with ether. After removing the solvent the oily
mixture was dissolved in 50ml of MeOH and 5g of Na2CO3 was added. The reaction mixture was
stirred violently overnight at room temperature, filtered, solvent removed and the remaining oil
was purified on a silica column with 30% Et2O/pentanes solvent yielding 0.4g (4.2mmol, 70%) of
147

the desired product 3.24.
1
H NMR (400 MHz, CDCl3) 5.95 (dtt, J = 14.8, 5.6, 1.8 Hz, 1H), 5.70
(dtt, J = 15.3, 5.4, 1.5 Hz, 1H), 4.22 – 4.06 (m, 3H), 2.98 (ddq, J = 5.5, 2.9, 1.5 Hz, 2H), 2.12 (t, J
= 2.7 Hz, 1H).

3.25
(E)-undeca-2-en-5,8-diyn-1-ol (3.25): To a 100ml flame-dried round-bottom flask under
argon 1.2g (6.3mmol) of CuI, 1.0g (6.7mmol) of NaI and 0.9g (6.5mmol) of K2CO3 were added.
0.2g (2.1mmol) of alcohol 3.25 and 0.64ml (0.92g, 6.2mmol) of 1-bromo-2-pentyne in 6ml of
anhydrous DMF were cannulated in. After the reaction mixture was allowed to stir overnight in
dark at room temperature, it was worked up with NH4Cl aqueous solution and extracted with ether.
After removing the solvent the mixture was purified on a silica column with 20% EtOAc/hexanes
to afford 0.18g (1.1mmol, 52%) of the desired product 3.25.
1
H NMR (600 MHz, CDCl3) 5.94 –
5.87 (m, 1H), 5.72 – 5.65 (m, 1H), 4.16 – 4.11 (m, 2H), 3.16 – 3.13 (m, 2H), 2.97 – 2.93 (m, 2H),
2.21 – 2.13 (m, 2H), 1.12 (t, J = 7.5 Hz, 3H).
13
C NMR (151 MHz, CDCl3) 130.79, 126.76, 82.18,
73.62, 63.35, 21.88, 14.01, 12.53, 9.88.

3.26
(2E,5Z,8Z)-undeca-2,5,8-trien-1-ol (3.26): The reaction can prove unsuccessful if either
there is not enough quinolone or the reaction mixture is too concentrated (not enough solvent
added). In a 100ml round-bottom flask 0.18g (1.1mmol) of compound 3.25 was dissolved in 30ml
of EtOAc, and 0.05ml of quinolone and 20mg of Lindlar catalyst were added. The reaction mixture
was purged with hydrogen and monitored by TLC. After completion, the reaction mixture was
filtered out, solvent removed and the remaining fraction was purified on silica column with 25%
EtOAc/hexanes solvent yielding 0.2g (1.2mmol, 92%) of the desired product 3.26.

1
H NMR (400
MHz, CDCl3) 5.75 – 5.61 (m, 2H), 5.49 – 5.25 (m, 4H), 4.13 – 4.04 (m, 2H), 2.87 – 2.70 (m, 4H),
148

2.13 – 1.96 (m, 4H), 0.97 (t, J = 7.5 Hz, 3H).
13
C NMR (101 MHz, CDCl3) 132.22, 131.20, 127.06,
126.93, 63.83, 30.13, 25.61, 20.70, 14.40.

3.27
((2S,3S)-3-((2Z,5Z)-octa-2,5-dien-1-yl)oxiran-2-yl)methanol (3.27): Flame-dry a 10 ml
flask with 25mg 4Å molecular sieve powder in it and add 1 ml of anhydrous DCM. Cool down the
flask to -20⁰C and add 0.02ml of (+)-Diethyl tartrate, 0.03ml of Ti(O-iPr)4 and 0.72ml of 5M t-
BuOOH were added sequentially. After stirring for 1 hour 0.20g (1.2mmol) of alcohol 3.26
dissolved in 2 ml (1ml, then again 1ml) of anhydrous DCM was cannulated into the solution and
the reaction stirred further for 3 hours. The reaction mixture was filtered, DCM removed, and the
mixture was purified on a silica column with 30% EtOAc/hexanes to afford product 3.27 (0.22g,
1.2mmol, 98%).
1
H NMR (400 MHz, CDCl3) 5.62 – 5.22 (m, 4H), 3.97 – 3.83 (m, 1H), 3.68 –
3.56 (m, 1H), 3.06 – 2.87 (m, 2H), 2.83 – 2.66 (m, 1H), 2.51 – 2.24 (m, 1H), 2.15 – 1.91 (m, 4H),
1.81 – 1.70 (m, 1H), 1.02 – 0.91 (m, 3H).

3.28
(2R,3S)-3-((2Z,5Z)-octa-2,5-dien-1-yl)oxirane-2-carbaldehyde (3.28): On the open air,
to a 50ml flask containing 0.22g (1.21mmol) of the alcohol 3.27 ~1g of NaHCO3 and 0.67g
(1.6mmol) of Dess-Martin periodinane were added together with a drop of tap water. After 2h the
reaction mixture showed completion by TLC and was worked up with 50ml of sodium thiosulfate-
sodium bicarbonate solution, extracted with dichloromethane (4x30ml) and dried over sodium
sulfate. Sodium sulfate was filtered out, solvent removed and the remaining mixture was purified
on a column with 15% EtOAc/hexanes yielding 0.11g (0.61mmol, 50%) of the aldehyde 3.16.
149

1
H NMR (400 MHz, CDCl3) 9.03 (t, J = 6.0 Hz, 1H), 5.67 – 5.24 (m, 4H), 3.32 – 3.20 (m,
1H), 3.20 – 3.11 (m, 1H), 2.80 (s, 1H), 2.58 – 2.37 (m, 1H), 2.12 – 1.95 (m, 4H), 1.01 – 0.93 (m,
3H).
13
C NMR (101 MHz, CDCl3) 198.59, 132.81, 132.34, 126.34, 121.85, 59.29, 58.65, 56.87,
31.28, 29.42, 26.95, 25.48.

3.29
(2E,4E)-5-((2S,3S)-3-((2Z,5Z)-octa-2,5-dien-1-yl)oxiran-2-yl)penta-2,4-dienal (3.29):
The reaction should not be done over 4h which leads to gradual deterioration of the reaction
yields. To 10ml pear-shaped flame-dried flask 0.15g (0.83mmol) of aldehyde 3.28 and 0.38g
(1.25mmol) of (triphenylphosphoranylidene)acetaldehyde were dissolved in 3ml of anhydrous
toluene and refluxed for 2h. Then (triphenylphosphoranylidene)acetaldehyde was added again
(0.13g, 0.43mmol). After 2h more TLC (20% EtOAc/Hexanes) showed completion, the reaction
mixture was dried down on a rotary evaporator and the remaining fraction was purified on column
with 10%EtOAc/hexanes solvent (500ml), then switching to 15%EtOAc/hexanes (300ml). 0.1g
(0.49mmol) of mono-reacted aldehyde 3.30 was recovered and 0.04g (0.17mmol, 21%) of the
clean product 3.29 obtained. Product 3.29:
1
H NMR (400 MHz, CDCl3) 9.57 (d, J = 7.9 Hz, 1H),
7.08 (dd, J = 15.3, 11.0 Hz, 1H), 6.68 – 6.58 (m, 1H), 6.17 (dd, J = 15.4, 7.9 Hz, 1H), 5.98 (dd, J
= 15.3, 7.4 Hz, 1H), 5.64 – 5.24 (m, 4H), 3.29 – 3.13 (m, 1H), 3.00 – 2.86 (m, 1H), 2.84 – 2.68
(m, 1H), 2.55 – 2.31 (m, 1H), 2.10 – 1.97 (m, 4H), 1.00 – 0.93 (m, 3H).

13
C NMR (101 MHz,
CDCl3) 193.73, 150.12, 141.28, 132.54, 132.33, 132.03, 131.11, 126.59, 122.76, 60.82, 56.92,
31.74, 29.74, 22.81, 14.28.
Mono-reacted aldehyde 3.30:
1
H NMR (400 MHz, CDCl3) 9.56 (d, J = 7.7 Hz, 1H), 6.54 (dd, J =
15.7, 6.9 Hz, 1H), 6.38 (ddd, J = 15.7, 7.6, 0.6 Hz, 1H), 5.62 – 5.24 (m, 4H), 3.37 (dd, J = 6.8,
2.1 Hz, 1H), 3.02 (td, J = 5.2, 2.0 Hz, 1H), 2.84 – 2.76 (m, 2H), 2.58 – 2.36 (m, 2H), 2.12 – 2.00
(m, 2H), 1.01 – 0.94 (m, 3H).

150

3.5 Spectra

Figure 3.1:
1
H NMR spectrum of compound 3.2
151

Figure 3.2:
13
C NMR spectrum of compound 3.2
152

Figure 3.3:
1
H NMR spectrum of compound 3.3
153

Figure 3.4:
13
C NMR spectrum of compound 3.3
154

Figure 3.5:
1
H NMR spectrum of compound 3.4

155

Figure 3.6:
13
C NMR spectrum of compound 3.4

156

Figure 3.7:
1
H NMR spectrum of compound 3.5

157

Figure 3.8:
13
C NMR spectrum of compound 3.5

158

Figure 3.9:
1
H NMR spectrum of compound 3.6

159

Figure 3.10:
13
C NMR spectrum of compound 3.6

160

Figure 3.11:
1
H NMR spectrum of compound 3.7

161

Figure 3.12:
13
C NMR spectrum of compound 3.7

162

Figure 3.13:
1
H NMR spectrum of compound 3.8

163

Figure 3.14:
13
C NMR spectrum of compound 3.8

164

Figure 3.15:
1
H NMR spectrum of compound 3.9

165

Figure 3.16:
13
C NMR spectrum of compound 3.9

166

Figure 3.17:
1
H NMR spectrum of compound 3.10

167

Figure 3.18:
13
C NMR spectrum of compound 3.10

168

Figure 3.19:
1
H NMR spectrum of compound 3.11

169

Figure 3.20:
13
C NMR spectrum of compound 3.11

170

Figure 3.21:
1
H NMR spectrum of compound 3.12

171

s

Figure 3.22:
13
C NMR spectrum of compound 3.12

172

Figure 3.23:
1
H NMR spectrum of compound 3.24
173

Figure 3.24:
1
H NMR spectrum of compound 3.25
174

Figure 3.25:
13
C NMR spectrum of compound 3.25
175

Figure 3.26:
1
H NMR spectrum of compound 3.26
176

Figure 3.27:
13
C NMR spectrum of compound 3.26
177

Figure 3.28:
1
H NMR spectrum of compound 3.27
178

Figure 3.29:
1
H NMR spectrum of compound 3.28
179

Figure 3.30:
13
C NMR spectrum of compound 3.28
180

Figure 3.31:
1
H NMR spectrum of compound 3.29
181

Figure 3.32:
13
C NMR spectrum of compound 3.29
182

Figure 3.33:
1
H NMR spectrum of compound 3.30
183

Chapter 4: Total Synthesis of the Methyl
(4Z,7Z,12E,14S,16Z,19Z,21R)-14,21-dihydroxydocosa-4,7,12,16,19-
pentaen-10-ynoate
4.1 Introduction
It was shown that omega-3 fatty acids significantly improve wound healing in the blister
wound model
45
, and when applied directly to wounds with gel-controlled release
46
. Further
research investigations, with the help of splinted excisional wound murine model, led to the
discovery of a novel series of 14,21-diHDHA lipid mediators that significantly improve wound
healing
47
. They were shown to be generated with the help of 12-lipoxigenase and cytochrome P450
working in tandem. The discovered biosynthetic pathway is presented below on Scheme 4.1:

Scheme 4.1. Biosynthetic scheme of the formation of novel 14,21-diHDHA lipid mediators that
were shown to be extremely important for wound healing process.
184

It can be seen from the scheme that 14,21-diHDHA diastereomers are produced from
docosahexaenoic acid (DHA) with the help of 12-LOX and p450. 12-LOX is able to introduce
peroxide at 14
th
position that is further converted to hydroxyl group. P450, in turn, is capable of
introducing hydroxyls both at 14
th
and 21
st
positions. Thus, the formation of 14,21-lipid mediators
presumably occurs through 14- and 21- HDHA isomers by P450 and by 12-LOX.
In the current work we set out to synthesize 14S, 21R – diHDHA. The synthesis was not
fully finished but plenty of work was done towards this goal. The problems encountered, possible
solutions and proposals for further work towards the goal of synthesis of enantiomerically pure
14,21-lipid mediators are discussed in the next section.

185

4.2 Results
4.2.1 Retrosynthetic Analysis of the Methyl (4Z,7Z,12E,14S,16Z,19Z,21R)-
14,21-dihydroxydocosa-4,7,12,16,19-pentaen-10-ynoate
Retrosynthetic analysis of the target compound 4.27 is presented on Scheme 4.2 below.
Compound 4.27 was retrosynthetically split at 10,11 double bond the construction of which was
envisioned to be made through two key steps: Sonogashira coupling
26
of the vinyl iodide 4.18 with
ester 4.23 that has terminal triple bond, and then stereoselective reduction of the triple bond at
10,11 position. So, the terminal triple bond of 4.23 served as a retrosynthetic equivalent of 10,11
cis- double bound in the target compound 4.27.

Scheme 4.2. Retrosynthetic analysis of the compound 4.27
186

Trans- vinyl iodide moiety of compound 4.18, that can be created by Takai reaction
20
from
aldehyde group, established 12,13-trans double bound through Sonogashira coupling
26
. Other four
double bonds that have cis- configuration: 4,5; 7,8; 16,17; 19,20; were constructed by using typical
Lindlar hydrogenation
13
of the respective triple bonds. Alcohol 4.14 can be obtained from
propargyl bromide 4.7 and terminal alkyne 4.11 through copper-catalyzed coupling. Compound
4.11 contains hydroxyl that establishes (S) – configuration at 14
th
position in the target compound
4.27. It can be established by the stereospecific (S)-protected glycidol opening reaction
42
. The
other (R)-hydroxyl group configuration at 21
st
position in 4.27 comes from compound 4.7 and was
proposed to be generated by Corey-Bakshi-Shibata (CBS) reduction
48
of the respective ketone
compound.

4.2.2 Synthesis of Building Blocks of the Methyl (4Z,7Z,12E,14S,16Z,19Z,21R)-
14,21-dihydroxydocosa-4,7,12,16,19-pentaen-10-ynoate
The synthesis of the compound 4.7 that establishes the stereochemistry of the hydroxyl
group at carbon 14 in the target compound 4.27 is presented on scheme 4.2 below.

Scheme 4.3. Synthesis of alcohol 4.7. (a) BuLi, THF, -78⁰C  0⁰C, 56%; (b) CBS, catechol
borane, EtNO2, 58%; (c) TBDPSCl, DMAP, imidazole, DCM, 65%; (d) CSA, MeOH/DCM, 85%;
(e) PPh3, NBS, DCM, 91%; (f) TBAF, THF, 42%;
187

TBS-protected propargyl alcohol was reacted with BuLi producing the respective lithium
acetylide which reacted with acetylmorpholine giving ketone 4.2
49
. Next key step b that actually
was supposed to introduce the enantiomerically pure alcohol stereocenter at position 22 of the
target compound 4.27 with (R)-configuration most probably failed and produced (R, S)-mixture of
the diastereomeres. Such an assumption was made due to observation of doubling of carbon signals
in compounds further down the line of the synthesis. For example, on Scheme 4.4 below we see
six signals from three alcoholic carbons of two diastereomers (see also figures in the spectra section of the
current chapter).

Scheme 4.4. Alcohol region of compound 4.15 shows the doubling of carbon signals that
is attributed to the mixture of diastereomers.
The unsuccessful CBS-reduction might be attributed to the sub stoichiometric amounts of
CBS while most probably stoichiometric were needed and/or the need of dimethylsulfide borane
instead of catechol borane. As a good alternative Noyori hydrogenation
50
is proposed to try in the
188

future attempts at the pure enantiomeric synthesis. Another method that might work has recently
been utilized for the synthesis of natural products (R)-Strongylodiols C and D
51
.
The other hydroxyl stereocenter is supposed to be enantiomerically pure due to the fact that
we have been using the procedure for a long time and the quality of the products has been
thoroughly tested
42
. The scheme of the 14
th
alcohol stereocenter enantiomeric generation through
epoxide opening is presented on the Scheme 4.5 below.

Scheme 4.5. Synthesis of the protected diol 4.11. (a) TBSCl, DMAP, imidazole, DCM, 98%; (b)
BuLi, THF, Et2O BF3, 63%; (c) TBDPSCl, DMAP, imidazole, DCM; then MeOH, Na2CO3, 60%;
The enantiomerically pure glycidol was protected with TBS group and introduced into
stereospecific reaction of epoxide opening at -78 ⁰C. The obtained free hydroxyl group of
compound 4.9 was further protected with TBDPS group to allow for easier TBS-selective group
removal in further steps.

189

On the Scheme 4.6 the synthesis of the key intermediate 4.18 is presented.

Scheme 4.6. Synthesis of the key diol 4.18. (a) CuI, NaI, K2CO3, DMF, 67%; (b) TBDPSCl,
DMAP, imidazole, DCM, 86%; (c) CSA, MeOH/DCM, 57%; (d) H2/Lindlar cat., quinoline,
EtOAc, 66%; (e) DMP, NaHCO3, DCM, 67%; (f) CHI3, CrCl2, THF, 33%; (g) TBAF, THF, 50%;
Propargyl bromide 4.7 was coupled with terminal alkyne 4.11 yielding 4.12. The hydroxyl
group of 4.12 was protected with TBDPS-group and TBS-group was selectively deprotected using
CSA reagent furnishing 4.14
42
. Selective hydrogenation with Lindlar catalyst in the presence of
quinolone
13
yielded compound 4.15 which established two cis-double bonds configuration. It
should be noted that it is crucial for the hydrogenation to have enough of quinolone to avoid side
reactions and overhydrogenation products. The reaction is sped up with larger volumes of EtOAc,
so generally if the reaction is sluggish, it can be sped up by reaction mixture dilution with EtOAc.
Then, primary alcohol group was oxidized with Dess-Martin periodinane (DMP) reagent
17
. The
reaction is best done on the open air with an addition of a drop of water. Previously we used to use
190

dry conditions under argon which gave lower yields and larger reaction times. The obtained
aldehyde was converted to trans-vinyl iodide 4.17 with Takai reaction
20
.
Dr. Min Zhu provided us with the compound 4.21 (see his dissertation work for further
details)
42
.

Scheme 4.7. Synthesis of the methyl ester 4.21 accomplished by Min Zhu. (a) CuI, NaI, K2CO3,
DMF; (b) NBS, PPh3, DCM; (c) CuI, NaI, K2CO3, DMF.
Repeating copper-catalyzed couplings with TMS-propargyl bromide for epoxy maresin1
(see chapter 3) we found the yields to be unacceptable using the regular procedure
42
. Thus, we
tried another one
43
that utilizes Bu4NCl, Na2CO3 and CuI and is set up at 0 ⁰C and it stably gives
two times higher yields when one of the starting materials was TMS-propargyl bromide substrate.
So, even though for the current synthesis regular procedure was utilized (due to the fact we have
not yet found the better procedure in the literature), in future attempts, if any issues found with the
regular conditions, the other procedure can be utilized that can be found in Chapter 3 for
compound 3.22.

191

Compound 4.21 was further selectively hydrogenated and TMS-group removed (Scheme
4.8 below)
42
.

Scheme 4.8. Synthesis of the methyl ester 4.23. (a) H2/Lindlar cat., quinoline, EtOAc, then (b)
MeOH, Na2CO3, 59%;
Finally compounds 4.18 and 4.23 were coupled together using regular Sonogashira reaction
conditions - Scheme 4.9.

Scheme 4.9. Final steps of the synthesis: Sonogashira coupling and failed attepmpt at reducing
10,11 - triple bond of 4.24
First, it should be noted that regular Sonogashira reaction conditions
26
that utilizes CuI and
Pd(PPh3)4 is generally inferior to the conditions that we found in the literature
21
and utilized later
for the syntheses of other compounds: see Chapter 2 of the present work and Dr. Jeremy Winkler
52

192

and Dr. Stephen Glynns’ Dissertation works
25
for additional examples. The improved procedure
does not use CuI (which can lead to terminal alkyne dimerization side reactions) and instead of
unstable and light sensitive Pd(PPh3)4 directly, generates it in situ from much more stable
Pd(OAc)2 and PPh3, is much easier in implementation and generally gives higher yields. The
procedure was reported by French researches, and for all of our attempts proved to be superior to
the regular Sonogashira reaction conditions.
The next step - triple bond Boland reduction using Ni/Al/Zn, H2O/MeOH reaction
conditions
22
was not working and gave no measurable quantities of the product. The same issue
was faced with RvD5 which also has dienyne moieties. Ni/Al/Zn – H2O reaction is generally
effective for the reduction of the compounds that have trieneyne moiety, for dienyne it works way
worse, for enyne usually being completely unsuccessful. So, we found a better procedure that can
be utilized for the hydrogenation of TBDPS-protected compounds with enyne bonds motif
24
, and
applied it successfully with high yield for RvD5 (See Chapter 2 of the present work) in the current
work and for other compounds in our lab too.

193

4.3 Conclusion
Thus an attempt towards the synthesis of 14S, 21R –diHDHA lipid mediator was pursued.
The results of the current work can be used to improve on the current approach. Several
possibilities for improvement and how the synthesis may be finally finished can be found in
resolvin D5 (RvD5) total synthesis successfully finished and discussed in Chapter 2.

194

4.4 Experimental Procedures

4.2
5-((tert-butyldimethylsilyl)oxy)pent-3-yn-2-one (4.2): Under the argon to a solution of
3.45g (20mmol) of TBS-protected propargyl alcohol 4.1 in 25ml of DrySolv THF in flame-dried
100ml flask, 8ml (20mmol) of 2.5M BuLi THF solution was added dropwise over 5min at -78 ⁰C.
After 30min the solution was warmed up to 0 ⁰C and 2.3ml (20mmol) of acetyl morpholine
dissolved in 10ml of DrySolv THF was cannulated to the reaction mixture. After 1h stirring at 0
⁰C the reaction was quenched with saturated NH4Cl solution and extracted with diethyl ether
(4x30ml). Ether was removed on the rotary evaporator and the remaining oily mixture was purified
on silica column with 3%EtOAc / hexanes solvent yielding 2.38g (56%) of the desired product
4.2.
1
H NMR (400 MHz, CDCl3) 4.46 (s, 2H), 2.35 (s, 3H), 0.94 – 0.89 (m, 9H), 0.16 – 0.11 (m,
6H).

13
C NMR (101 MHz, CDCl3) 184.27, 90.28, 84.42, 51.65, 32.66, 25.87, 18.39.

4.3
5-((tert-butyldimethylsilyl)oxy)pent-3-yn-2-ol (4.3): To 100ml flame-dried flask 30ml of
EtNO2 was added and cooled to -78 ⁰C. To the flask 2.25ml (2.3mmol) of 1M CBS reagent and
then 1.91ml (18.0mmol) of catechol borane were added. After 15min 2.38g (11.2mmol) of the
ketone 4.2 in 8ml of EtNO2 was cannulated. After 3h the reaction was warmed up to room
temperature, quenched with saturated NaHCO3 solution and extracted with diethyl ether (4x30ml).
The organic extract was washed with 100ml of 1M NaOH solution. Ether was removed on the
rotary evaporator and the remaining oil was purified on silica column with 10% EtOAc / hexanes
solvent yielding 1.4g (58%) of 4.3.
1
H NMR (600 MHz, CDCl3) 4.56 (dddd, J = 11.8, 6.6, 5.2,
195

1.7 Hz, 1H), 4.34 (d, J = 1.5 Hz, 2H), 1.73 (dd, J = 5.3, 2.1 Hz, 1H), 1.45 (d, J = 6.5 Hz, 3H), 0.93
– 0.89 (m, 9H), 0.14 – 0.11 (m, 6H).
13
C NMR (151 MHz, CDCl3) 86.76, 82.92, 58.60, 51.86,
25.99, 24.35, 18.47, -4.95.

4.4
2,2,5,10,10,11,11-heptamethyl-3,3-diphenyl-4,9-dioxa-3,10-disiladodec-6-yne (4.4):
To flame-dried 100ml round-bottom flask 1.4g (6.5mmol) of 2.5, 1.5g (22mmol) of imidazole,
0.5g(4mmol) dimethylaminopyridine were added under argon and dissolved in 30ml of
dichloromethane, and 5.8ml (22mmol) of tertbuthyldiphenylsilylchloride was added to the reaction
mixture. After 15h the mixture was worked up with saturated ammonium chloride solution,
extracted with dichloromethane, dried down on the rotary evaporator and purified on a silica
column with 3% EtOAc/hexanes solvent yielding 1.92g (1.6mmol, 65%) of 4.4.
1
H NMR (400
MHz, CDCl3) 7.77 – 7.66 (m, 4H), 7.47 – 7.34 (m, 6H), 4.50 (qt, J = 6.5, 1.6 Hz, 1H), 4.24 (t, J =
1.6 Hz, 2H), 1.37 (d, J = 6.5 Hz, 3H), 1.09 – 1.05 (m, 9H), 0.91 – 0.87 (m, 9H), 0.11 – 0.07 (m,
6H).
13
C NMR (151 MHz, CDCl3) 136.10, 135.92, 134.05, 133.79, 129.80, 129.73, 127.70, 127.59,
87.16, 82.35, 60.17, 51.87, 31.75, 27.03, 25.99, 25.26, 22.82, 19.36, 18.43, 14.28, -4.94.

196

4.5
4-((tert-butyldiphenylsilyl)oxy)pent-2-yn-1-ol (4.5): Under argon to a solution of
protected diol 4.4 (1.92g, 4.2mmol) in 40ml 1:1 mixture of CH2Cl2 and MeOH, camphor sulfonic
acid (0.59g, 2.5mmol) was added at room temperature and monitored for 1 h by TLC. The reaction
was quenched with Et3N (1.2 mL, 13.3 mmol) and the solvent was evaporated in vacuo without
workup. The crude reaction mixture was purified on silica gel using 15% EtOAc / hexanes solvent
to afford alcohol 4.5 (1.22g, 85%).
1
H NMR (400 MHz, CDCl3) 7.78 – 7.67 (m, 4H), 7.46 – 7.35
(m, 6H), 4.53 (qt, J = 6.5, 1.7 Hz, 1H), 4.08 (dd, J = 6.2, 1.7 Hz, 2H), 1.41 (d, J = 6.5 Hz, 3H),
1.08 – 1.05 (m, 9H).
13
C NMR (101 MHz, CDCl3) 136.19, 135.94, 134.13, 133.82, 129.89, 129.78,
127.75, 127.52, 88.37, 82.23, 60.05, 51.22, 27.01, 25.17, 19.30.

4.6
((5-bromopent-3-yn-2-yl)oxy)(tert-butyl)diphenylsilane (4.6): 1.22g (3.6mmol) of
compound 4.5 was dissolved in 13 ml of DCM and the mixture was cooled down to 0 ⁰C. To the
reaction mixture 1.04g (4.0mmol) of PPh3 was added and after 10 min 0.71g (4.0mmol) of NBS.
After stirring for 40min at 0 ⁰C the reaction mixture was worked up with saturated sodium
bicarbonate solution, extracted with DCM(3x30ml), organic fractions were combined and the
solvent removed on a rotary evaporator. The remaining oil was purified on a silica gel column with
1% EtOAc/hexanes solvent yielding 1.31g (91%) of pure 4.6.
1
H NMR (600 MHz, CDCl3) 7.77 –
7.66 (m, 4H), 7.46 – 7.35 (m, 6H), 4.50 (qt, J = 6.6, 1.9 Hz, 1H), 3.81 (d, J = 1.9 Hz, 2H), 1.39 (d,
J = 6.5 Hz, 3H), 1.09 – 1.06 (m, 9H).

13
C NMR (151 MHz, CDCl3) 136.09, 135.92, 133.72, 133.64,
129.91, 129.82, 127.78, 127.65, 89.36, 78.93, 60.12, 27.01, 24.96, 19.33, 14.72.

197

4.7
5-bromopent-3-yn-2-ol (4.7): To a solution of 0.65g (1.6mmol) of 4.6 in 40ml of THF
1.6ml of 1M TBAF (1.6mmol) was added. The mixture was stirred overnight at room temperature
and then solvent was removed on a rotary evaporator. The remaining oily mixture was purified on
a silica column changing from 25% EtOAc/hexanes to 20% solvent yielding 0.11g (42%) of 4.7.
1
H NMR (400 MHz, CDCl3) 4.63 – 4.55 (m, 1H), 3.94 (d, J = 1.9 Hz, 2H), 1.81 (d, J = 5.4 Hz,
1H), 1.46 (d, J = 6.6 Hz, 3H).
13
C NMR (101 MHz, CDCl3) 88.65, 79.36, 60.55, 58.59, 24.16.

4.9
(S)-1-((tert-butyldimethylsilyl)oxy)-5-(trimethylsilyl)pent-4-yn-2-ol (4.9): To a
solution of TMS acetylene (2.8ml, 20mmol) in 20 ml THF was added 8ml of 2.5M n-BuLi (39.8
mmol) at -78°C. After 10min 2.5ml (20mmol) of BF3·Et2O was added drop wise at - 78°C. After
10min more, 2.5g (13mmol) of (R)-O-t-butyldimethylsilyl glycidol 4.8 was added to the reaction
mixture and the reaction was stirred for 3h at -78°C. The reaction mixture was warmed up to room
temperature, quenched with 50ml of saturated aqueous NH4Cl and extracted with Et2O (3x50ml).
The extract was dried on the rotary evaporator and the remaining mixture purified on silica column
with 7% EtOAc/hexanes solvent furnishing 2.2g (7.7mmol) of the desired product 4.9.
1
H NMR
(400 MHz, CDCl3) δ 3.78 (dt, J = 11.1, 5.9 Hz, 1H), 3.72 (dd, J = 10.0, 4.1 Hz, 1H), 3.63 (dd, J =
10.0, 5.6 Hz, 1H), 2.51 – 2.41 (m, 2H), 1.64 (s, 1H), 0.91 (s, 11H), 0.14 (s, 2H), 0.09 (s, 5H), 0.08
(s, 6H).
13
C NMR (400 MHz, CDCl3) δ 102.96, 87.19, 70.32, 65.60, 26.03, 24.67, 18.48, 0.17, -
5.24, -5.28.

198

4.11
(S)-2,2,8,8,9,9-hexamethyl-3,3-diphenyl-5-(prop-2-yn-1-yl)-4,7-dioxa-3,8-
disiladecane (4.11): To a solution of 1.1g (3.8mmol) of 4.9 in 40ml of DrySolv DCM was added
2.9ml (11.1mmol) of TBDPS-Cl, 0.66g of imidazole (9.7mmol), and 0.07g (0.6mmol) of DMAP
at 0°C. The reaction was allowed to stir at room temperature overnight. It was then quenched with
40ml of saturated aqueous NH4Cl and extracted with Et2O (3x30ml). The combined extract was
dried on the rotary evaporator and purified on silica column with 2% of EtOAc/hexanes solvent.
The obtained purified TMS-protected compound 4.10 was further introduced to the next step: it
was dissolved in 40ml of MeOH, 10g of Na2CO3 added and stirred for overnight. The reaction
mixture was filtered, solvent removed on rotary evaporator and the remaining oil was purified on
silica column with 3% EtOAc/hexanes solvent furnishing 0.76g (2.3mmol, 60% over two steps)
of 4.11.
1
H NMR (400 MHz, CDCl3) 3.86 – 3.75 (m, 1H), 3.60 – 3.47 (m, 2H), 2.50 (dd, J = 16.8,
5.3 Hz, 1H), 2.30 (dd, J = 16.8, 6.5 Hz, 1H), 0.89 (s, 18H), 0.14 (s, 9H), 0.11 (s, 3H), S7 0.08 (s,
3H), 0.05 (s, 3H), 0.02 (s, 3H).
13
C NMR (400 MHz, CDCl3) 104.86, 85.95, 72.25, 66.83, 26.13,
26.01, 18.53, 18.29, 0.23, -2.78, -4.29, -4.44, -5.18, -5.24.

4.12
(9S)-10-((tert-butyldimethylsilyl)oxy)-9-((tert-butyldiphenylsilyl)oxy)deca-3,6-diyn-2-
ol (4.12): To a mixture of 0.17g (0.9mmol) of CuI, 0.13g (0.9mmol) of NaI, 0.12g (0.9mmol) of
K2CO3 in 5ml of DMF in flame-dried flask under argon, 0.11g (0.7mmol) of 4.7 with 0.40g
(0.9mmol) of 4.11 were cannulated in 4ml of DrySolv DMF. The reaction mixture was stirred for
overnight, worked up with saturated ammonium chloride and extracted with Et2O (4x40ml). The
organic fractions were combined, solvent removed and the purification on a silica gel column with
10% EtOAc/hexanes yielded 0.24g (67%) of 4.12.
1
H NMR (400 MHz, CDCl3) 7.74 – 7.68 (m,
4H), 7.45 – 7.34 (m, 6H), 4.54 – 4.45 (m, 1H), 3.83 (p, J = 5.5 Hz, 1H), 3.53 (d, J = 5.5 Hz, 2H),
199

3.12 – 3.08 (m, 2H), 2.45 – 2.36 (m, 1H), 2.34 – 2.25 (m, 1H), 1.68 (d, J = 5.2 Hz, 1H), 1.42 (d, J
= 6.6 Hz, 3H), 1.06 (s, 9H), 0.83 (s, 9H), -0.04 (s, 3H), -0.07 (s, 3H).

13
C NMR (126 MHz, CDCl3)
136.11, 136.02, 134.29, 134.22, 129.75, 129.74, 127.67, 127.66, 82.15, 79.07, 78.16, 75.10, 72.42,
65.75, 58.64, 27.09, 26.03, 24.48, 24.12, 19.51, 18.43, 9.93, -5.34.

4.13
(12S)-12-((tert-butyldiphenylsilyl)oxy)-2,2,5,15,15,16,16-heptamethyl-3,3-diphenyl-
4,14-dioxa-3,15-disilaheptadeca-6,9-diyne (4.13 To flame-dried 100ml round-bottom flask
0.24g (0.45mmol) of 4.12, 0.06g (0.9mmol) of imidazole, 0.03g(0.3mmol) dimethylaminopyridine
were added under argon and dissolved in 30ml of dichloromethane, and 0.24ml (0.9mmol) of
tertbuthyldiphenylsilylchloride was added to the reaction mixture. After 15h the mixture was
worked up with saturated ammonium chloride solution, extracted with dichloromethane, dried
down on the rotary evaporator and purified on a silica column with 2% EtOAc/hexanes solvent
yielding 0.30g (0.4mmol, 86%) of 4.13.
1
H NMR (400 MHz, Chloroform-d) 7.81 – 7.61 (m, 9H),
7.49 – 7.32 (m, 12H), 4.52 – 4.42 (m, 1H), 3.89 – 3.82 (m, 1H), 3.61 – 3.58 (m, 2H), 3.58 – 3.48
(m, 2H), 2.51 – 2.28 (m, 2H), 1.37 (d, J = 6.5 Hz, 3H), 1.10 – 1.05 (m, 18H), 0.15 – 0.12 (m, 3H),
-0.03 – -0.05 (m, 3H), -0.05 – -0.08 (m, 3H).

4.14
(2S)-2,9-bis((tert-butyldiphenylsilyl)oxy)deca-4,7-diyn-1-ol (4.14): Under argon to a
solution of protected diol 4.13 (0.30g, 0.4mmol) in 4ml 1:1 mixture of CH2Cl2 and MeOH,
camphor sulfonic acid (0.045g, 0.2mmol) was added at room temperature and monitored for 1 h
by TLC. The reaction was quenched with Et3N (0.11mL, 0.78mmol) and the solvent was
evaporated in vacuo without workup. The crude reaction mixture was purified on silica gel using
200

15% EtOAc / hexanes solvent to afford alcohol 4.14 (0.15g, 57%).
1
H NMR (400 MHz,
Chloroform-d) 7.77 – 7.65 (m, 8H), 7.43 – 7.31 (m, 12H), 4.44 (qt, J = 6.2, 1.8 Hz, 1H), 3.82 (p,
J = 5.4 Hz, 1H), 3.52 (d, J = 5.4 Hz, 2H), 2.97 (d, J = 1.9 Hz, 2H), 2.44 – 2.35 (m, 1H), 2.32 –
2.23 (m, 1H), 1.35 (d, J = 6.5 Hz, 3H), 1.07 – 1.06 (m, 9H), 1.06 – 1.04 (m, 9H).
13
C NMR (151
MHz, Chloroform-d) 136.11, 135.98, 135.90, 135.83, 135.81, 133.56, 133.48, 130.13, 130.09,
130.05, 129.76, 129.67, 128.01, 127.99, 127.91, 127.86, 127.67, 127.53, 82.74, 80.54, 78.19,
76.63, 76.11, 72.48, 72.16, 70.58, 65.65, 65.43, 34.83, 31.75, 29.22, 27.12, 27.02, 23.57.

4.15
(2S,4Z,7Z)-2,9-bis((tert-butyldiphenylsilyl)oxy)deca-4,7-dien-1-ol (4.15): 0.15g (0.22
mmol) of 4.14 was dissolved in 15ml of ethyl acetate. 0.1ml of quinolone, and 0.01g of Lindlar
catalyst were added. The reaction mixture was purged with hydrogen and carefully monitored by
the TLC (10%EtOAc/hexanes). After the reaction completion the mixture was filtered, solvent
removed and purification was done with 8%EtOAc/hexanes on a silica column yielding 0.1g
(0.2mmol, 66%) of the product 4.15.
1
H NMR (500 MHz, Chloroform-d) 7.69 – 7.62 (m, 8H),
7.44 – 7.29 (m, 12H), 5.51 – 5.44 (m, 1H), 5.17 – 5.10 (m, 1H), 5.10 – 4.96 (m, 2H), 4.57 – 4.49
(m, 1H), 3.75 – 3.69 (m, 1H), 3.48 – 3.35 (m, 2H), 2.28 – 2.08 (m, 3H), 2.03 – 1.97 (m, 1H), 1.14
(d, J = 6.2 Hz, 3H), 1.07 – 1.05 (m, 9H), 1.04 – 1.02 (m, 9H).
13
C NMR (151 MHz, Chloroform-
d) 136.02, 136.00, 135.95, 135.81, 135.26, 135.23, 134.71, 130.13, 130.10, 130.00, 129.97,
129.64, 129.56, 127.92, 127.80, 127.64, 127.54, 126.20, 126.18, 124.98, 73.79, 73.75, 66.03,
66.00, 65.78, 34.83, 31.75, 31.66, 31.64, 27.18, 27.09, 25.79, 25.76.

201

4.16
(2S,4Z,7Z)-2,9-bis((tert-butyldiphenylsilyl)oxy)deca-4,7-dienal (4.16): Alcohol 4.15
(0.08 g, 0.12 mmol) was dissolved in 5 ml DCM, then 0.10g Dess-Martin periodinane and 0.10g
NaHCO3 were added and the slurry solution was stirred for 1 hour. The reaction was worked up
with 1:1 NaHCO3/Na2S2O3 saturate solution and extracted 3 times (20ml) with DCM. DCM was
removed on the rotary evaporator and the mixture was purified on a silica column with 5%
EtOAc/hexanes to afford the aldehyde 4.16 (0.06g, 67%).
1
H NMR (600 MHz, CDCl3) 7.69 –
7.60 (m, 8H), 7.44 – 7.29 (m, 12H), 5.52 – 5.45 (m, 1H), 5.23 – 5.16 (m, 1H), 5.15 – 5.07 (m, 1H),
5.05 – 4.96 (m, 1H), 4.55 – 4.48 (m, 1H), 4.18 – 4.11 (m, 1H), 4.09 – 4.03 (m, 1H), 3.96 – 3.90
(m, 1H), 2.28 – 2.02 (m, 4H), 1.14 (d, J = 6.2 Hz, 3H), 1.03 (s, 18H).
13
C NMR (151 MHz, CDCl3)
185.37, 158.82, 136.08, 136.01, 135.96, 135.94, 135.41, 134.68, 133.64, 130.76, 130.74, 129.98,
129.86, 129.66, 129.59, 127.81, 127.79, 127.65, 127.55, 125.94, 124.05, 70.49, 70.44, 69.78,
69.77, 31.99, 31.75, 27.08, 27.05, 25.82, 25.79, 24.72, 22.81, 19.38, 19.32.

4.17
(6Z,9Z,12S)-12-((E)-2-iodovinyl)-2,2,5,15,15-pentamethyl-3,3,14,14-tetraphenyl-4,13-
dioxa-3,14-disilahexadeca-6,9-diene (4.17): To 0.09g (0.7mmol) chromium(II) chloride mixed
with 4ml of THF 0.10g (0.3mmol) of iodoform and 0.06g (0.09mmol) of 4.17 dissolved in 2ml of
THF were cannulated under 0 ⁰C. The reaction mixture was stirred at 0 ⁰C for 4h after which it
was worked up with 10ml of saturated ammonium chloride solution and extracted with 3x10ml of
dichloromethane. Solvent was removed and the mixture was purified on a silica column with pure
pentane, then with 2% ethyl ether/pentane solvent yielding 0.025g (0.03mmol, 33%) of 4.17.
1
H
NMR (400 MHz, CDCl3) 7.70 – 7.57 (m, 8H), 7.44 – 7.30 (m, 12H), 6.38 (ddd, J = 14.4, 6.6, 1.7
Hz, 1H), 5.92 (dd, J = 14.4, 2.9 Hz, 1H), 5.49 (t, J = 9.6 Hz, 1H), 5.23 – 4.97 (m, 3H), 4.58 – 4.48
202

(m, 1H), 4.06 – 3.98 (m, 2H), 2.30 – 2.11 (m, 1H), 1.65 – 1.53 (m, 1H), 1.15 (d, J = 6.2 Hz, 3H),
1.05 (s, 9H), 1.04 (s, 9H).
13
C NMR (151 MHz, CDCl3) 147.84, 136.01, 135.95, 135.26, 135.25,
134.70, 134.40, 133.89, 133.58, 130.26, 129.92, 129.90, 129.65, 129.58, 127.73, 127.72, 127.65,
127.55, 126.24, 124.35, 124.33, 75.67, 75.63, 66.03, 66.01, 35.14, 27.12, 27.09, 25.91, 25.87,
24.75, 19.46, 19.32.

4.18
(3Z,6Z,9S,10E)-11-iodoundeca-3,6,10-triene-2,9-diol (4.18): To a solution of 0.025g
(0.032mmol) of 4.17 in 1ml of THF 0.23ml of 1M TBAF (0.23mmol) was added. The mixture
was stirred overnight at room temperature and then solvent was removed on a rotary evaporator.
The remaining oily mixture was purified on a silica column changing from 45% EtOAc/hexanes
yielding 0.005g (0.016mmol, 50%) of 4.18.
1
H NMR (400 MHz, CDCl3) 6.59 (ddd, J = 14.5, 5.8,
2.0 Hz, 1H), 6.38 (ddd, J = 14.5, 6.0, 1.3 Hz, 1H)., 5.68 – 5.57 (m, 1H), 5.49 – 5.36 (m, 3H), 4.67
(dddt, J = 12.6, 10.0, 6.3, 3.1 Hz, 1H), 4.24 – 4.14 (m, 1H), 3.02 (ddt, J = 31.6, 16.1, 8.5 Hz, 1H),
2.84 – 2.64 (m, 1H), 2.45 – 2.22 (m, 3H), 1.25 (d, J = 1.5 Hz, 1H).
13
C NMR (126 MHz, CDCl3)
171.29, 147.67, 147.54, 134.44, 134.27, 131.98, 131.85, 128.67, 128.58, 124.77, 77.62, 77.54,
73.95, 73.76, 63.84, 63.59, 34.97, 34.54, 26.32, 23.63, 23.53.

4.23
Methyl (4Z,7Z)-undeca-4,7-dien-10-ynoate (4.23): 1.4g (5.3mmol) of 4.21 was dissolved
in 100ml of ethyl acetate. 1ml of quinolone, and 0.1g of Lindlar catalyst were added. The reaction
mixture was purged with hydrogen and carefully monitored by the TLC (5%EtOAc/hexanes).
After the reaction completion the mixture was filtered and solvent removed. The remaining
mixture was dissolved in 40ml of methanol and 5g (47mmol) of Na2CO3 was added. The mixture
was stirred under argon for overnight, filtered and solvent removed. The remaining oil was purified
with 5%EtOAc/hexanes on a silica column yielding 0.6g (3.1mmol, 59%) of the product 4.23.
1
H
203

NMR (400 MHz, CDCl3) 5.51 – 5.34 (m, 4H), 3.68 (s, 3H), 3.02 – 2.90 (m, 2H), 2.88 – 2.77 (m,
2H), 2.45 – 2.34 (m, 4H), 1.98 (t, J = 2.7 Hz, 1H).
13
C NMR (101 MHz, CDCl3) 173.64, 130.13,
128.68, 128.50, 124.24, 82.70, 68.29, 51.73, 34.10, 25.63, 22.95, 17.04.

4.24
Methyl (4Z,7Z,12E,14S,16Z,19Z)-14,21-dihydroxydocosa-4,7,12,16,19-pentaen-10-
ynoate (4.24): Precaution: Copper-free Sonogashira reaction should work much better for the
reaction; see chapter 2, compound 2.41 for further details. Under the argon 2mg (0.006mmol) of
vinyl iodide 4.18, 10mg (0.052mmol) alkyne 4.23, 6mg (0.005mmol) Pd(PPh3)4, 1.9mg
(0.01mmol) CuI, and 0.14ml (1mmol) Et3N were added in 1.5ml benzene and stirred at room
temperature overnight. The reaction mixture was worked up with saturated ammonium chloride
aqueous solution and ether. The organic layer was combined and washed with brine. Evaporated
the solvent and purified the mixture on a silica column using 20% EtOAc/hexanes to afford the
1.4mg of pure product 4.24 (0.004mmol, 67%).
1
H NMR (400 MHz, CDCl3) 6.07 (ddd, J = 14.5,
8.7, 5.9 Hz, 1H), 5.79 – 5.67 (m, 1H), 5.68 – 5.54 (m, 1H), 5.52 – 5.33 (m, 6H), 4.73 – 4.62 (m,
1H), 4.28 – 4.12 (m, 1H), 3.68 (s, 3H), 3.12 – 2.92 (m, 3H), 2.89 – 2.65 (m, 3H), 2.46 – 2.22 (m,
7H), 2.14 – 1.99 (m, 1H), 1.26 – 1.24 (m, 3H).
13
C NMR (151 MHz, CDCl3) 173.70, 143.66,
143.50, 134.41, 134.29, 131.61, 131.57, 129.93, 129.90, 128.80, 128.69, 128.53, 128.43, 125.20,
124.66, 124.49, 124.48, 110.74, 89.28, 78.35, 71.72, 71.52, 63.82, 63.54, 35.36, 34.92, 34.12,
32.09, 30.81, 29.86, 29.82, 29.52, 26.34, 25.66, 23.59, 23.48, 22.96, 22.85, 18.01.

204

4.4 Spectra

Figure 4.1:
1
H NMR spectrum of compound 4.2

205

Figure 4.2:
13
C NMR spectrum of compound 4.2
206

Figure 4.3:
1
H NMR spectrum of compound 4.3
207

Figure 4.4:
13
C NMR spectrum of compound 4.3
208

Figure 4.5:
1
H NMR spectrum of compound 4.4
209

Figure 4.6:
13
C NMR spectrum of compound 4.4
210

Figure 4.7:
1
H NMR spectrum of compound 4.5
211

Figure 4.8:
13
C NMR spectrum of compound 4.5
212

Figure 4.9:
1
H NMR spectrum of compound 4.6
213

Figure 4.10:
13
C NMR spectrum of compound 4.6
214

Figure 4.11:
1
H NMR spectrum of compound 4.7
215

Figure 4.12:
13
C NMR spectrum of compound 4.7
216

Figure 4.13:
1
H NMR spectrum of compound 4.12
217

Figure 4.14:
13
C NMR spectrum of compound 4.12
218

Figure 4.15:
1
H NMR spectrum of compound 4.13
219

Figure 4.16:
1
H NMR spectrum of compound 4.14
220

Figure 4.17:
13
C NMR spectrum of compound 4.14

221

Figure 4.18:
1
H NMR spectrum of compound 4.15
222

Figure 4.19:
13
C NMR spectrum of compound 4.15

223

Figure 4.20:
1
H NMR spectrum of compound 4.16
224

Figure 4.21:
13
C NMR spectrum of compound 4.16
225

Figure 4.22:
1
H NMR spectrum of compound 4.17
226

Figure 4.23:
13
C NMR spectrum of compound 4.17
227

Figure 4.24:
1
H NMR spectrum of compound 4.18
228

Figure 4.25:
13
C NMR spectrum of compound 4.18
229

Figure 4.26:
1
H NMR spectrum of compound 4.23
230

Figure 4.27:
13
C NMR spectrum of compound 4.23
231

Figure 4.28:
1
H NMR spectrum of compound 4.24
232

Figure 4.29:
13
C NMR spectrum of compound 4.24
233

Chapter 5: Total Synthesis of the Methyl (5S,6R,E)-5,6-
dihydroxy-8-(5-((R,E)-3-hydroxyoct-1-en-1-yl)thiophen-2-yl)oct-7-
enoate (Thiolipoxin)

5.1 Introduction
Lipoxins are endogenously produced lipid mediators that have potent anti-inflammatory
effects
53
. They are produced by platelets in combination with neutrophils
4
. Two of them are
presented on Scheme 5.1 below.

Scheme 5.1. Two endogenous lipoxins: lipoxin A4 and lipoxin B4 that have potent anti-
inflammatory effects
One of the studied pathways by which lipoxins A4 and B4 are formed involves the
peroxidation of arachidonic acid to form 15S-HpETE that is reduced further to 15S-HETE – key
intermediate in the biosynthesis of lipoxins – by 15-lipoxygenase (15-LOX) and further epoxide
formation-opening reaction by 5-lipoxygenase (5-LOX) that occurs inside of activated
polymorphonuclear cells (PMNs). The biosynthetic pathway of the formation of LXA4 and its
epimeric form is presented on Scheme 5.2 on the next page
4
.

234

Scheme 5.2. Biosynthesis of LXA4 and its epimeric form.
Endogenously produced lipoxins are unstable and rapidly get inactivated by eicosanoid
oxidoreductase
54
. The synthesis of stable fatty acid compounds that would mimic endogenous
lipoxins is one of the research directions in search for drugs that help managing inflammatory
processes. One of the approaches which proved to make potent and stable anti-inflammatory
compounds that mimic lipoxins is to substitute the cis-double bond in the lipoxin tetraene moiety
235

with a benzene ring since tetraene system is chemically unstable
4,55
. Also, benzene ring makes the
analogs more rigid disallowing achieving the conformation needed for eicosanoid oxidoreductase
(EOR) substrate recognition, thus making them much worse substrates for one the deactivation
pathways. Another approach is to substitute one of the fatty branches with some similar groups.
Some of the lipoxin analogs are presented on Scheme 5.3 below
4
.

Scheme 5.3. Some lipoxin A4 (LXA4) analogs previously synthesized and the anti-inflammatory
properties
The presence of 15-(R)-hydroxy group instead of (S)- was also shown to make lipoxins resistant
to EOR deactivation. The activity of the benzo-lipoxins is also highly dependent on the angle
between the two saturated branches that comes out of the benzene ring. Compound 3 (Scheme 5.3
above) that has metha-substituents was shown to have higher anti-inflammatory activity than
ortho-substituted analogs, e.g. compound 2. Thus, it is of interest to see how the other
substitution/change of the benzene core to other heterocyclic compounds would affect the
236

biological properties of the analogs. In the current work we synthesized another lipoxin analog
that contains thiophene ring which is shown on the Scheme 5.4 below.

Scheme 5.4. New lipoxin analog synthesized in the current dissertation work. First known
example of a lipoxin analog with a heterocycle in the tetraene moiety.

237

5.2 Results
5.2.1 Retrosynthetic Analysis of the Methyl (5S,6R,E)-5,6-dihydroxy-8-(5-
((R,E)-3-hydroxyoct-1-en-1-yl)thiophen-2-yl)oct-7-enoate
Retrosynthetically compound 5.15 can be split into three key building blocks: trans-iodide
5.7, 5-bromo-2-thienylboronic acid 5.12 and alcohol 5.9 as shown on Scheme 5.5 below.

Scheme 5.5. Retrosynthetic scheme of the thiolipoxin 5.15
Three main building blocks can be combined together sequentially by using different Suzuki
reaction conditions. One trans-double bond of 5.15 is established by the usage of trans-vinyl iodide
5.7 which is accessible from the respective aldehyde through Takai reaction; the other is
guaranteed by hydroboration of the alcohol 5.9. Vinyl iodide is easily accessible from
commercially available deoxy-D-ribose 5.1. Protected compound 5.9 can be obtained from the
unprotected and commercially available stereochemically pure (R)-oct-1-yn-3-ol alcohol.

238

5.2.2 Synthesis of Building Blocks of the (5S,6R,E)-5,6-dihydroxy-8-(5-((R,E)-
3-hydroxyoct-1-en-1-yl)thiophen-2-yl)oct-7-enoate
Synthesis of the key building block 5.7 (Scheme 5.6) starts from deoxy-D-ribose 5.1 which
is a commercially available compound. Wittig reaction of the aldehyde group with Methyl
(triphenylphosphoranylidene)acetate yields compound 5.2. Double bond of the compound 5.2 can
be easily hydrogenated with Pd/C to yield the respective reduced compound 5.3, the three alcohol
groups of which were further protected with three TBS groups.

Scheme 5.6. Synthesis of key vinyl iodide building block 5.7; (a) Ph3PCHCO2Me, THF, reflux,
98%; (b) Pd/C, 5%, H2, 98%; (c) TBSCl, DMAP, imidazole, DCM, 40%; (d) CSA, MeOH / DCM
= 1:1, 0⁰C, Et3N, 35%; (e) DMSO, COCl2, Et3N, 82%; (f) CHI3, CrCl2, THF, 38%;

Camphorsulphonic acid (CSA) reagent allowed for the selective removal of the primary protected
alcohol group with low yield. At the time we did not know that there is much better alternative for
the selective primary TBS-group removal: Py-HF
29
reagent described in the 2
nd
chapter of the
present dissertation work. So, it is better to try using Py-HF instead of the CSA to improve the
yield of the selective deprotection. The alcohol group of 5.5 was oxidized using Swern conditions
56

239

and the resulting aldehyde group was further converted to trans-vinyl iodide using Takai
olefination
20
thus furnishing key building block 5.7.
Another key building block 5.11 was obtained and directly used in the next Suzuki
coupling. The steps to prepare 5.11 are outlines on Scheme 5.7 below.

Scheme 5.7. Synthesis of the catechol boronate 5.11. (a) TBSCl, DMAP, imidazole, DCM, 81%;
(b) No solvent reaction, 65 ⁰C, overnight, and was introduced directly without workup and
purification to the nect Suzuki coupling.

Alcohol 5.8 which is commercially available in enantiomeric pure form was protected with TBS
group and terminal triple bond was hydroborated with catechol borane to yield trans-boronic ester
5.11
57
.

240

The final steps that combine all of the three key building blocks is presented below on
Scheme 5.8. Vinyl iodide group of 5.7 was reacted with commercially available 5.12 using Suzuki
reaction affording 5.13 with high yield which was then coupled with 5.11 to furnish 5.14 also with
high yield.

Scheme 5.8. Synthesis of the final thiolipoxin compound 5.15. (a) K3PO4, Pd(PPh3)4, DMF, 32%;
(b) 5.11, K2CO3, Pd(PPh3)4, H2O, dioxane, 95%; (c) TBAF, THF, then CH2N2, 45%.
Compound 5.14 was deprotected with TBAF to furnish mixture of the respective acid, methyl ester
5.15 and the lactone which was treated with diazomethane to convert the acid to methyl ester
42,52
.
The formation of the lactone that cannot be avoided due to the fact that alcohol group is at 5
th

carbon from the ester group which leads to cyclization with 6-membered ring formation lowering
the yield of 5.15
52
.

241

5.3 Conclusion
Thus, thio-lipoxin 5.15 was obtained in 9 steps with the total yield of 0.6%. Key steps
involved Takai and hydroboration reactions for establishing the configuration of the two trans-
double bonds and finally two Suzuki coupling reactions. The yield might be improved by using
Py-HF selective deprotection of the compound 5.4 instead of using CSA reagent.

5.4 Experimental Procedures

5.4
Methyl (5S,6R)-5,6,7-tris((tert-butyldimethylsilyl)oxy)heptanoate (5.4): 250ml flask
was flame-dried, filled with argon and 10.4g (69.1mmol) of t-butyldimethylsilylchloride, 0.33g
(2.7mmol) dimethylaminopyridine, 4.7g (69.1mmol) of imidazole and 50ml of dichloromethane
were added. The reaction mixture was cooled down to 0 ⁰C and 2.2g (11.5mmol) of 5.2 was
cannulated in 5ml of anhydrous DCM. The reaction mixture was warmed up to room temperature
stirred overnigh. The reaction was treated with 200ml of saturated ammonium chloride solution
and extracted with 4x30ml of dichloromethane. Combined organic fraction was dried over sodium
sulfate, filtered out, solvent removed and purified on a silica column with 3%EtOAc/hexanes
solvent yielding 2.5g (4.7mmol, 40%) of 5.4.
1
H NMR (400 MHz, CDCl3) 3.75 – 3.69 (m, 1H),
3.67 – 3.61 (m, 4H), 3.60 – 3.54 (m, 1H), 3.47 – 3.41 (m, 1H), 2.32 – 2.23 (m, 2H), 1.82 – 1.68
(m, 1H), 1.67 – 1.49 (m, 2H), 1.49 – 1.37 (m, 1H), 0.95 – 0.79 (m, 27H), 0.11 – -0.03 (m, 18H).

242

5.5
Methyl (5S,6R)-5,6-bis((tert-butyldimethylsilyl)oxy)-7-hydroxyheptanoate (5.5): It is better to
use Py-HF (see chapter 2, AT-RvD2 synthesis, compound 2.30) which can give 70% yield or more
instead of generally below 40% for the procedure described here with CSA reagent. To a 100ml
flask 21ml of MeOH and 21ml of DCM were added, mixed and cooled down to 0 ⁰C. To the
prepared solvent 1.34g (2.5mmol) of 5.4 and 0.53g (2.3mmol) of camphorsulfonic acid (CSA)
were added. The reaction was carefully controlled by TLC and when it showed the completion,
the reaction mixture was quenched with 1.1ml (7.9mmol) of Et3N. The solvent was removed on
rotary evaporator and the remaining oil was purified on silica column with 15% EtOAc/hexanes
solvent yielding 1.0g (2.3mmol, 35%) of the product 5.5.

5.6
Methyl (5S,6S)-5,6-bis((tert-butyldimethylsilyl)oxy)-7-oxoheptanoate (5.6): From our
experience, Dess-Martin oxidation (see chapters 2 and 3) generally works faster with same or
higher yields, more reliable, and the reaction set up is much easier. In a 25ml flame-dried flask
under argon 5ml of anhydrous DCM and 0.21ml (3.0mmol) of DMSO were added and cooled
down to -78 ⁰C. To the reaction mixture 0.18ml (2.1mmol) of oxalyl chloride was added. After
15min 0.41g (1.0mmol) of alcohol 5.5 in 2ml of anhydrous DCM was cannulated in and the
reaction mixture was stirred for 45min more. Then, 0.71ml (5.1mmol) of Et3N was added and
waited for 3h more. The reaction mixture was warmed up to room temperature, worked up with
10ml of water and extracted with diethyl ether (3x10ml). The combined organic extract was dried
on rotary evaporator and the remaining oily mixture was purified on silica column with 5%
EtOAc/hexanes solvent furnishing 0.34g (0.8mmol, 82%) of the desired product 5.6.
1
H NMR
(400 MHz, CDCl3) 9.60 (s, 1H), 3.99 – 3.94 (m, 1H), 3.90 – 3.85 (m, 1H), 3.67 (s, 3H), 2.40 –
2.34 (m, 2H), 2.01 – 1.77 (m, 2H), 0.94 – 0.89 (m, 9H), 0.88 – 0.84 (m, 9H), 0.10 – 0.05 (m, 12H).
243

5.7
Methyl (5S,6R,E)-5,6-bis((tert-butyldimethylsilyl)oxy)-8-iodooct-7-enoate (5.7): To a
50ml flame-dried round-bottom flask, 0.49g (4.0mmol) chromium(II) chloride was transferred in
glove box under nitrogen atmosphere and 4ml of DrySolv THF was added. Then, 0.95g (2.4mmol)
of iodoform and 0.34g (0.8mmol) of aldehyde 5.6 dissolved in 2ml of THF were cannulated to the
reaction mixture under 0 ⁰C. The reaction mixture was stirred at 0 ⁰C for 3h after which it was
worked up with 100ml of saturated ammonium chloride solution and extracted with 3x30ml of
dichloromethane. Solvent was removed and the mixture was purified on a silica column with pure
pentane, then with 2% EtOAc/hexanes solvent yielding 0.17g (0.3mmol, 39%) of 5.7.
1
H NMR
(400 MHz, CDCl3) 6.47 (dd, J = 14.5, 7.1 Hz, 1H), 6.21 (d, J = 14.5 Hz, 1H), 3.86 (t, J = 6.0 Hz,
1H), 3.64 (s, 3H), 3.58 (q, J = 5.2 Hz, 1H), 2.38 – 2.31 (m, 2H), 1.85 – 1.75 (m, 2H), 0.85 (s, 18H),
0.05 – -0.03 (m, 12H).

5.13
Methyl (5S,6R,E)-8-(5-bromothiophen-2-yl)-5,6-bis((tert-butyldimethylsilyl) oxy)oct-
7-enoate(5.13): In a 10ml flame-dried flask, 0.08g (0.38mmol)) of (3-bromophenyl)boronic acid,
0.20g (0.96mmol) of K3PO4 and 0.005g (0.04mmol) of Pd(PPh3)4 were dissolved in 1 ml of
anhydrous DMF under argon. 0.17g (0.32mmol) of vinyl iodide 5.7 was dissolved in 1 ml DMF
and cannulated to the solution. The reaction was allowed to stir at 65 ⁰C for 5 hours. Work up with
50ml of NH4Cl aqueous saturated solution and extract with ether (4x20ml). The solvent was
removed on rotary evaporator and the resulting oily mixture was purified on a silica column using
5% EtOAc/hexanes solvent to afford 0.058g (0.1mmol) of the product 5.13.
1
H NMR (400 MHz,
CDCl3) 6.90 (d, J = 3.8 Hz, 1H), 6.68 – 6.62 (m, 1H), 6.53 – 6.46 (m, 1H), 5.88 (dd, J = 15.8, 7.0
Hz, 1H), 4.02 (ddd, J = 6.8, 5.2, 1.2 Hz, 1H), 3.70 – 3.62 (m, 4H), 2.44 – 2.37 (m, 2H), 1.92 – 1.83
244

(m, 2H), 0.92 – 0.89 (m, 9H), 0.88 – 0.86 (m, 9H), 0.09 – 0.06 (m, 3H), 0.05 – 0.03 (m, 3H), 0.03
– 0.01 (m, 6H).

5.14
Methyl(5S,6R,E)-5,6-bis((tert-butyldimethylsilyl)oxy)-8-(5-((R,E)-3-((tert-
butyldimethylsilyl) oxy)oct-1-en-1-yl)thiophen-2-yl)oct-7-enoate (5.14): To a 10ml pear-
shaped flame-dried flask 0.06g (0.25mmol) of TBS-protected alcohol 5.9 was added under
nitrogen in glove box. The flask was filled with argon, cooled down to 0 ⁰C with an ice bath, and
0.027ml (0.03g, 0.25mmol) of cateholborane was added. Ice-bath was switched to oil bath, argon
ballon removed, flask parafilmed, and the reaction mixture was heated up to 70 ⁰C and stirred
overnight. The next day the reaction mixture was cooled down to room temperature and 0.005g
(0.04mmol) Pd(PPh3)4 and 0.25g (1.8mmol) of K2CO3 were added under nitrogen. The reaction
mixture was filled with argon. Under argon 0.03g (0.05mmol) of 5.13 was cannulated into the
reaction mixture in 0.8ml of anhydrous dioxane, after which 1.6ml of deoxygenated water was
added. Argon balloon was removed from the flask, the flask parafilmed and left stirring overnight
at 80 ⁰C. Next day the reaction was dried down on a rotary evaporator and purified with 1.5% of
EtOAc/hexanes furnishing 0.04g (0.05mmol, 95%) of the product 5.14.
1
H NMR (400 MHz,
CDCl3) 6.77 – 6.73 (m, 2H), 6.53 (dd, J = 15.7, 1.2 Hz, 2H), 5.95 (ddd, J = 26.5, 15.7, 6.6 Hz,
2H), 4.25 – 4.13 (m, 1H), 4.08 – 4.01 (m, 1H), 3.70 – 3.64 (m, 4H), 2.51 (dd, J = 5.8, 2.6 Hz, 1H),
2.41 (dd, J = 9.0, 7.0 Hz, 1H), 1.92 – 1.84 (m, 2H), 1.29 – 1.21 (m, 13H), 0.92 – 0.91 (m, 9H),
0.90 – 0.90 (m, 9H), 0.88 – 0.87 (m, 9H), 0.08 – 0.02 (m, 18H).

245

5.15
Methyl (5S,6R,E)-5,6-dihydroxy-8-(5-((R,E)-3-hydroxyoct-1-en-1-yl)thiophen-2-
yl)oct-7-eno -ate (5.15): To a 10ml round bottom flask containing 0.04g (0.05mmol) of 5.14 3ml
of anhydrous THF and 0.3ml of TBAF were added at room temperature. The reaction mixture was
stirred for 3h, worked up with 10ml of saturated aqueous solution of NH 4Cl and extracted with
diethyl ether (15x3ml). The organic extract was treated with freshly prepared diazomethane, dried
down and purified with 5% MeOH/DCM solvent furnishing 0.01g (0.02mmol) of the product 5.15.
1
H NMR (600 MHz, CDCl3) 6.83 – 6.78 (m, 2H), 6.75 – 6.69 (m, 1H), 6.67 – 6.60 (m, 1H), 6.04
(ddd, J = 15.7, 10.7, 6.7 Hz, 2H), 4.27 – 4.20 (m, 2H), 4.12 (q, J = 7.1 Hz, 1H), 3.69 (s, 3H), 2.59
– 2.48 (m, 2H), 2.39 – 2.32 (m, 1H), 1.90 – 1.81 (m, 2H), 1.81 – 1.68 (m, 3H), 0.95 – 0.82 (m,
9H).
13
C NMR (126 MHz, CDCl3) 177.38, 141.74, 139.97, 133.12, 127.46, 126.52, 124.81, 123.39,
81.94, 72.83, 72.58, 51.06, 37.48, 31.91, 28.64, 25.24, 22.75, 21.39, 14.19.

246

5.5 Spectra

Figure 5.1:
1
H NMR spectrum of compound 5.4
247

Figure 5.2:
1
H NMR spectrum of compound 5.7
248

Figure 5.3:
1
H NMR spectrum of compound 5.13
249

Figure 5.4:
1
H NMR spectrum of compound 5.14
250

Figure 5.5:
1
H NMR spectrum of compound 5.15
251

Figure 5.6:
13
C NMR spectrum of compound 5.15
252

Figure 5.7:
1
H-
1
H COSY NMR spectrum of compound 5.14

253

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Abstract (if available)

Abstract Current work provides the accomplished total syntheses of potent pro-resolving antiinflammatory lipid mediators to help further biological research in the field. ❧ In Chapter 1 a brief introduction is done into the field of lipid mediators and their involvement in inflammatory processes. ❧ Chapter 2 discusses the total syntheses of resolvin D5 (RvD5) and aspirin-triggered resolvin D2 (AT-RvD2) which play significant role in the resolution phase of inflammation with and without aspirin influence respectively. To accomplish the syntheses new reaction techniques were developed and already discovered were applied to improve the yields and reduce the number of steps. Of particular importance is epoxide opening reaction by pentynoic methyl ester the reaction conditions of which were optimized and helped to cut down the number of steps significantly

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Core Title Total synthesis of specialized pro-resolving lipid mediators and their analogs

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Publication Date 01/26/2017

Defense Date 08/09/2016

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