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Design and synthesis of helicene-based macromolecules

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Design and synthesis of helicene-based macromolecules

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DESIGN AND SYNTHESIS OF HELICENE-BASED MACROMOLECULES

by

Janet M. Olsen

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)

December 2014

Copyright 2014 Janet M. Olsen
ii
Dedication

To my sister, Jacelyn.

iii
Acknowledgements
First and foremost, I would like to thank Professor Thieo Hogen-Esch, my advisor, for his
guidance and support throughout my graduate experience. Thank you for always having an open
door, and for many valuable discussions. I am truly grateful for his encouragement and
mentorship. I am fortunate to have been a member of his research group.
I would like to extend a special thank you to those who have served on my qualifying
exam and dissertation committees: Professors G. K. Surya Prakash, Nicos Petasis, Richard
Brutchey, Ralf Langen, and Katherine Shing. I also wish to thank Professor Kyung Jung for
providing guidance during the early part of my graduate career, and the late Dr. Kyung Soo Yoo
for training me in experimental technique as a new graduate student. He is truly missed.
Thank you to the current and past members of the Hogen-Esch lab: Dr. Peng Jiang, Dr.
Victoria Piunova, Merve Yurdacan, Bing Xu, Ming Li, and Sergey Mukhin. You have all been
incredibly helpful to me throughout this process, and it has been a pleasure to work with you.
I also wish to thank the many friends I have made during my time in the USC chemistry
department. Dr. Jie Cao, Dr. Jamie Jarusiewicz, Dr. Frederick Krause, and Dr. Fang Wang have
been dear friends since our first year in the program together. Dr. Alejandra Beier, Dr. Beate
Burkhart, Dr. Anna Dawsey, Dr. Abigail Joyce, Dr. Somesh Kumar, Jenna Howard, Jotheeswari
Kothandaraman, Sankarganesh Krishnamoorthy, and Arjun Narayanan have each helped me
deepen my understanding of chemistry and made the graduate experience a more enjoyable one.
I am grateful for the opportunities and support during my time as a teaching assistant with
Dr. Jennifer Moore. Thank you for many insightful discussions, and for teaching me valuable
skills that will be helpful to me throughout my career.
iv
A special thanks to the staff of the Loker Hydrocarbon Institute and the USC Department
of Chemistry: Dr. Robert Anizfeld, Michele Dea, David Hunter, Jessy May, and Carole Phillips.
Finally, a heartfelt thanks to those closest to me: my mother and father, Deborah and
Thomas Olsen, my brother and sister, Timothy and Jacelyn, and my dear companion, Carl
Allendorph. Thank you for your continual support and encouragement. Without you, this would
not have been possible.

v
Table of Contents

Dedication ii
Acknowledgements iii
List of Figures vii
List of Schemes viii
Abstract x
List of Abbreviations and Symbols Used xi

Chapter 1. Introduction 1
1.1 Chiral Conjugated Polymers 1
1.2 The Development of Helicenes 4
1.3 Applications of Helicenes 6
1.4 References 8

Chapter 2. Synthesis and Polymerization of a [5]Helicene Monomer 10
2.1 Introduction 10
2.2 Monomer Design 15
2.3 Synthesis of a [5]Helicene Monomer 18
2.4 Polymerization of a [5]Helicene Monomer 25
2.5 Resolution 27
2.6 References 31

Chapter 3. Progress Toward a [6]Helicene Monomer 32
3.1 Introduction 32
3.2 Synthesis of a [6]Helicene Monomer 33
3.3 References 36

vi
Chapter 4. Conclusions 37
4.1 Summary of the Thesis 37
4.2 Future Work 38
4.3 References 36

Chapter 5. Experimental and Spectral Data 42
5.1 General Procedures 42
5.2 Chapter 2 Experimental and Spectral Data 44
5.3 Chapter 3 Experimental and Spectral Data 66
5.4 References 84

Bibliography 85

vii
List of Figures
Figure 1.1. Conjugated polymers with chiral pendant groups. 3
Figure 1.2. [5]Helicene. 3
Figure 1.3. [6]Helicene enantiomers and their helical configurations (M and P). 4 1-5
Figure 1.4. Helicenebisquinone used in SHG experiments. 7 1-8
Figure 2.1. 1,1’-Binaphthalene. 13 2-4
Figure 2.2. 1,1’-Binaphthyl-based helical polymer capable of mediating SHG. 13
Figure 2.3. R-1,1’-Bi-2-naphthol (BINOL) side and top views. 14 2-5
Figure 2.4. Target helicene monomer. 17 2-8
Figure 2.5. Bonding of an o-methoxy substituent with phosphorus in the cis-OPA
and the trans-OPA. 19 2-11

Figure 2.6. Ball-and-stick model of three units of a copolymer composed of
acetylene-functionalized [5]helicene and p-diiodobenzene. 25 2-16

Figure 2.7. Normalized absorption spectra of model monomer 2.14 and polymer 2.15
in CHCl
3
at 25 °C. 27 2-18

Figure 2.8. [6]Helicene with menthyl chiral auxiliaries at positions 2 and 15. 28
Figure 2.9. [6]Helicene with camphanic chiral auxiliaries at positions 3 and 14. 28
Figure 2.10. Helicene diol, a precursor to the monomer. 29 2-20
Figure 2.11. S(+)-2-(2,4,5,7-tetranitro-9-fluorenylidene-aminooxy) propionic acid (TAPA). 29
Figure 3.1. Target naphthalene (3.1) for the preparation of a [6]helicene, and
previously reported naphthalenes prepared by Furukawa (3.2 and 3.3. 33

Figure 4.1. Electron-withdrawing aryl connectors that can be prepared in one step
from commercially available starting materials. 40 4-4

viii
List of Schemes
Scheme 1.1. Photochemical preparation of [14]helicene. 5 1-6
Scheme 1.2. Enantioselective synthesis of a chiral alcohol in the presence of
(M)-(-)-[6]helicene. 6 1-8
Scheme 2.1. Synthesis of a helical conjugated polymer. 11 2-2
Scheme 2.2. Helical copolymer prepared from [6]helicene and a para-substituted aryl
connector. 11 2-3
Scheme 2.3. Cyclic polymer prepared from [6]helicene and an ortho-substituted aryl
connector. 12 2-3
Scheme 2.4. Unsuccessful attempts toward a helicene monomer. 15 2-6
Scheme 2.5. Conversion of a Z,Z-stilbene into a [5]helicene via a C-H arylation reaction. 16 2-7
Scheme 2.6. Simplified depiction of the preparation of a helicene-based copolymer
with electron acceptor (A) and electron donor (D) groups. 18
Scheme 2.7. Z,Z-selective preparation of a stilbene substrate for C-H arylation. 20
Scheme 2.8. Preparation of the triphenylphosphine salt. 20 2-11
Scheme 2.9. Preparation of the dialdehyde. 21 2-12
Scheme 2.10. Simplified depiction of DOM leading to the observed regiochemistry of the
dialdehyde. 21 2-12
Scheme 2.11. Preparation of the Z,Z-stilbene via a Wittig reaction. 22 2-13
Scheme 2.12. Palladium-mediated double C-H arylation reaction. 23 2-14
Scheme 2.13. Deprotection of the methoxy groups, followed by alkylation. 23
Scheme 2.14. Insertion of the TIPS-protected alkyne groups, followed by deprotection
of the TIPS groups. 24 2-15
Scheme 2.15. Preparation of a model monomer. 26 2-17
Scheme 2.16. Polymerization between the helicene monomer and p-diiodobenzene. 26
Scheme 3.1. Formation of a [6]helicene via a double C-H arylation reaction. 33
ix
Scheme 3.2. Preparation of the desired naphthalene. 34 3-3
Scheme 3.3. Preparation of the naphthalene-based triphenylphosphine salt. 34
Scheme 3.4. Stepwise preparation of the asymmetrical Z,Z-stilbene. 35 3-4
Scheme 3.5. C-H arylation to form the [6]helicene and subsequent demethylation. 35
Scheme 4.1. Possible route toward the preparation of a new triphenylphosphine salt. 38
Scheme 4-2. Preparation of a possible dimethylated Z,Z-stilbene. 39
Scheme 4.3. Synthesis of a new alkyne-functionalized helicene with methyl groups at the
1- and 14-positions. 39

x
Abstract
The synthetic route toward a helicene monomer and its subsequent copolymerization with
an aryl connector are presented. The introduction (Chapter 1) provides an overview of the
significance of chiral conjugated polymers. Following this, helicene and its properties are
discussed in the context of presenting it as a desirable component of these polymers.
Chapter 2 begins with a discussion of the desirable features of a helicene-based polymer
and continues with a description of the synthetic strategies that may be utilized to incorporate
desired functionalities. The route toward the helicene monomer is centered around a palladium-
catalyzed double C-H arylation reaction. The remaining reactions focus on either the preparation
of the precursor to this key transformation, or the subsequent functionalization that readies this
helicene for polymerization. The copolymerization of the functionalized helicene with an aryl
connector is described, along with the resulting absorption spectra, which provide evidence of the
desired extended conjugation between the monomer units.
Chapter 3 presents the progress made on a synthetic route toward a longer, more
conformationally stable helicene monomer. The C-H arylation is still utilized, but a modified
substrate for that reaction is required. Chapter 4 extends the theme of preparing a more stable
helicene, with the description of additional synthetic strategies toward this goal. Together, this
chemistry opens up helicenes as tunable components for use in new chiral conjugated polymers.

xi
List of Abbreviations and Symbols Used
δ chemical shift
Ac acetate
ACN acetonitrile
BPO benzoyl peroxide
Cy cyclohexyl
d doublet
DCM dichloromethane
DDQ 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
DEE diethyl ether
DEG diethylene glycol
DIPA diisopropylamine
DMA dimethylacetamide
DMF dimethylformamide
ε molar absorptivity
E trans
Et ethyl
HPLC high-performance liquid chromatography
h hour(s)
Hz hertz
J
XY
coupling constant between atom X and atom Y
m multiplet
Me methyl
xii
min minute(s)
mp melting point
NBS N-bromosuccinimide
NLO nonlinear optical
NMR nuclear magnetic resonance
q quartet
R
f
retardation factor
rt room temperature
SEC size exclusion chromatography
SHG second-harmonic generation
TBAF tetrabutylammonium fluoride
TEA triethylamine
THF tetrahydrofuran
TIPS triisopropylsilyl
TLC thin layer chromatography
TMEDA tetramethylethylenediamine
UV-Vis ultraviolet-visible
XPhos 2-dicyclohexylphosphino-2’,4’,6’-triisopropylbiphenyl
Z cis

1
Chapter 1. Introduction

1.1 Chiral Conjugated Polymers
Conjugated polymers represent an important class of structures within materials science.
1,2

Owing to the delocalization of their π electrons along the main chain, these macromolecules are
capable of impressive functions including electrical conductivity, luminescence, and photon-
harvesting.
3,4
These properties can be modified and tuned through manipulation of the
organization of these polymers,
5
and control over this arrangement is highly desirable in the
design of new organic materials.
Chiral conjugated polymers have attracted much interest, because they address
requirements not satisfied by their achiral counterparts. Circularly polarized photoluminescence,
6

a characteristic which is desirable for a number of photonic technologies including LCD
backlights and optical communication,
7
is a feature of certain chiral conjugated polymers. The
organization of these polymers into helices is often achieved through the incorporation of chiral
monomers, which are able to impart their sense of directionality to the larger structure.
3

Chiral molecules and polymers are noncentrosymmetric,
8
which is necessary for materials
capable of mediating second-order nonlinear optical (NLO) processes. Absorbing light of a
particular frequency and emitting photons of double that frequency, a process known as frequency
doubling or Second-Harmonic Generation (SHG), is an example of an NLO process. Materials
capable of this frequency doubling process are useful for the fabrication of laser sources emitting
blue light for biological, medical and electronic applications.
9
Additionally, these materials are of
interest for electro-optic (EO) devices.
10
With increasing amounts of data being transmitted
between sources and users, researchers are looking for ways to increase both the speed and
2
quantity of this transmission. In the context of long-range communication, optical fibers are
capable of transmitting more information with fewer losses when compared with copper wires.
10

However, in order for optical cables to be used, electrical signals must be translated into optical
ones and then translated back into electrical signals once the information has been transferred
over the fiber-optic network. This process of electronic-to-optical signal transduction is currently
the rate-determining step in fiber-optic data transfer. An EO modulator can mediate this process,
and these devices require noncentrosymmetric materials.
Commercial EO modulators are currently fabricated from inorganic crystals, such as
lithium niobate, but the EO coefficient (a measure of the control of the index of refraction of a
material by application of a voltage) is typically limited to 31 pm/V.
11
Through organic synthesis,
chromophores can be designed and tuned for specific NLO applications, and some of these
organic materials are capable of displaying EO coefficients an order of magnitude greater than
their inorganic counterparts.
12
Incorporating chiral chromophores into a polymer is a particularly
attractive strategy, because it facilitates the alignment of the polymers, which is required in order
for these effects to be observed.
9
Organic materials also offer the benefits of ease of fabrication
and processing when compared with inorganic crystals.
With these applications in mind, various chiral conjugated polymers have been prepared.
In many cases, chiral pendant groups are included to induce helicity in the main chain (Figure
1.1).
3
However, the helical sense of these polymers is often susceptible to conformational changes
dependent on external factors such as the composition of the solvent.
13
A more robust sense of
helicity can be achieved by incorporating chiral compounds into the main chain of a polymer.
14

Examples of polymers of this type exist,
15
but their full potential remains to be realized.

3

Figure 1.1. Conjugated polymers with chiral pendant groups.
13,16,17

One class of molecules which is poised to make a significant impact on chiral conjugated
materials is helicenes. Helicenes are polycyclic structures composed of ortho-fused aromatic
rings. The classic nomenclature for helicenes is the [n]helicene terminology, where n refers to the
number of ortho-fused rings.
18

Figure 1.2. [5]Helicene.
H
N O
ONa
O
H
n
O O
H
n
O O
O O
n
1
2
3
4 5
6
7
8
9
10 11
12
13
14
4
When n reaches five or more, the molecule experiences steric repulsion between the terminal
rings, causing the molecule to twist into a helix. When this twisting results in a right-handed
helix, it is denoted P (“plus”), and when a left-handed helix results, it is denoted M (“minus”).
19

Figure 1.3. [6]Helicene enantiomers and their helical configurations (P and M).
The inherent chirality of these molecules gives rise to large optical rotation (several thousand
degrees)
20
and high circular dichroism values.
19
Preparing a polymer featuring these units in its
backbone would allow for its evaluation as a chiral conjugated material, and is the focus of this
work.

1.2 The Development of Helicenes
More than one hundred years ago, a synthesis of [4]helicene was first reported.
21
This was
followed a few years later by a report of the first [5]helicene.
22
During the next few decades, the
preparations of several other helicenes were reported, but they were largely considered molecules
of curiosity and the number of publications per year remained stagnant.
19

A major turning point in the understanding of helicenes occurred in the 1950s, when
[6]helicene was both synthesized and resolved.
20
With this development, circular dichroism
(P)-(+)-[6]helicene
Clockwise helicity
Right-handed
(M)-(-)-[6]helicene
Anticlockwise helicity
Left-handed
5
spectroscopy
23
and specific rotation measurements
24
were used to characterize these molecules.
Subsequently, new syntheses for helicenes were developed, with a focus placed on increasing the
number of fused rings.
19

Development of the photochemical synthetic method for the preparation of helicenes in
the 1960s allowed for significantly longer versions to be accessed. This method features the
oxidative photocyclization of stilbene-type precursors and was used in the first synthesis of
[7]helicene,
25
as well as in the longest example, [14]helicene (Scheme 1.1).
26
The main drawback
of this method is the requirement of high dilution conditions to avoid dimerization of the stilbene
substrate. These concentrations allow for the production of only small amounts at a time (tens of
milligrams per liter), motivating the development of additional strategies for the synthesis of
helicenes.

Scheme 1.1. Photochemical preparation of [14]helicene.
In recent decades, efforts to fabricate helicenes have increased further, leading to a diverse
selection of strategies for their preparation. Diels-Alder cycloadditions,
27
olefin metathesis,
28
and
metal-mediated cycloadditions
29
have successfully been employed in more efficient synthetic
hν, I
2
C
6
H
6
[14]helicene
6
routes. These new methods made possible the fabrication of helicenes with varying functionality,
which allowed for their application in many different fields to be explored.

1.3 Applications of Helicenes
As inherently chiral molecules, helicenes have the potential to be useful in many
applications from asymmetric catalysis to materials chemistry. With the successful use of C
2
-
symmetric 1,1’-binaphthyl-based ligands in asymmetric catalysis,
30
helicenes (which also feature
C
2
-symmetry) were anticipated to be promising candidates in this field. In the 1980s, this concept
was explored, and functionalized helicenes were found to mediate many stereoselective reactions,
including epoxidations, alkylations, and the reduction of ketones.
31
Complete resolution of the
helicene ligands was not required for these reactions to take place. For example, merely
enantioenriched versions of unfunctionalized [5]- and [6]helicene were found to mediate the
enantioselective addition of diisopropyl zinc to aldehydes.
32

Scheme 1.2. Enantioselective synthesis of a chiral alcohol in the presence of (M)-(-)-[6]helicene.
Another significant milestone in the history of helicenes was reached in the 1990s, when a
study of the supramolecular aggregation of helicenebisquinones (Figure 1.4) was reported.
33
In
solution, π-interactions between individual helicene units acted as a driving force for their self-
assembly into columnar stacks. Films of the stacks comprised of enantiopure helicenes were
N
N
i-Pr
2
Zn
93% yield, 93% ee
t-Bu
H
O
N
N
t-Bu
OH
7
found to generate strong SHG signals, with a 30-fold increase in intensity compared with a film
made from the racemic version.
33
AFM images of films prepared from both racemic and
nonracemic samples of this helicene revealed that the nonracemic version allowed for better
helicene organization, resulting in large long-range assembly domains. This is contrasted with the
racemic version, which features many enantiomorphous domains. Given that both films were
composed entirely of molecules with identical connectivity, the ability of the nonracemic version
to organize more efficiently is directly responsible for the observed difference in response.
33

Figure 1.4. Helicenebisquinone used in SHG experiments.
Since this discovery, helicenes and helicene-based compounds have continued to be
featured in new applications. Several of these compounds have been evaluated as
semiconductors
34
with differing results for racemic versus nonracemic versions.
35
Helicenes have
also been used as emitters in organic light-emitting diodes (OLEDs).
36,37
Of great potential for
commercial application is the discovery that polymeric helicenes are capable of producing
circularly polarized electroluminescence,
7
a characteristic which is desirable for a number of
photonic technologies including LCD backlights and optical communication.
7
The list of
applications continues to grow, and new helicenes must be developed to meet the demand.

O
O
O
O
OC
12
H
25
OC
12
H
25
C
12
H
25
O
C
12
H
25
O
8
1.4 References
(1) Lehnherr, D.; Tykwinski, R. R. Aust. J. Chem. 2011, 64, 919.
(2) Günes, S.; Neugebauer, H.; Sariciftci, N. S. Chem. Rev. 2007, 107, 1324.
(3) Watanabe, K.; Suda, K.; Akagi, K. J. Mater. Chem. 2013, 1, 2797.
(4) Bundgaard, E.; Krebs, F. C. Sol. Energy Mater. Sol. Cells 2007, 91, 954.
(5) Hoeben, F. J. M.; Jonkheijm, P.; Meijer, E. W.; Schenning, A. P. H. J. Chem. Rev. 2005,
105, 1491.
(6) Oda, M.; Meskers, S.; Nothofer, H.; Scherf, U.; Neher, D. Synth. Met. 2000, 111–112, 575.
(7) Yang, Y.; Da, R.; Smilgies, D. Adv. Mater. 2013.
(8) Kauranen, M.; Verbiest, T.; Boutton, C.; Teerenstra, M. N.; Clays, K.; Schouten, A. j; Nolte,
R. J. M.; Persoons, A. Science 1995, 270, 966.
(9) Kajzar, F.; Chollet, P.-A. Poled Polymers and their Applications to SHG and EO Devices;
Miyata, S.; Sasabe, H., Eds.; Advances in Nonlinear Optics; Gordon and Breach Science
Publishers, 1997; Vol. 4.
(10) Dalton, L. In Polymers for Photonics Applications I; Advances in Polymer Science; Springer
Berlin Heidelberg, 2002; pp. 1–86.
(11) Turner, E. H. Appl. Phys. Lett. 1966, 8, 303.
(12) Kim, T.-D.; Kang, J.-W.; Luo, J.; Jang, S.-H.; Ka, J.-W.; Tucker, N.; Benedict, J. B.; Dalton,
L. R.; Gray, T.; Overney, R. M.; Park, D. H.; Herman, W. N.; Jen, A. K.-Y. J. Am. Chem.
Soc. 2007, 129, 488.
(13) Zhao, X.; Schanze, K. S. Langmuir 2006, 22, 4856.
(14) Cho, M. J.; Choi, D. H.; Sullivan, P. A.; Akelaitis, A. J. P.; Dalton, L. R. Prog. Polym. Sci.
2008, 33, 1013.
(15) Shockravi, A.; Javadi, A.; Abouzari-Lotf, E. RSC Adv. 2013, 3, 6717.
(16) Suda, K.; Akagi, K. Macromolecules 2011, 44, 9473.
(17) Satrijo, A.; Meskers, S. C. J.; Swager, T. M. J. Am. Chem. Soc. 2006, 128, 9030.
(18) Balaban, A. T. Polycycl. Aromat. Compd. 2003, 23, 277.
(19) Gingras, M. Chem. Soc. Rev. 2013, 42, 968.
(20) Newman, M. S.; Lednicer, D. J. Am. Chem. Soc. 1956, 78, 4765.
(21) Weitzenböck, H.; Lieb, R. Monatsh. Chem. Verw. TL 1912, 33, 549.
(22) Weitzenböck, R.; Klingler, A. Monatsh. Chem. 1918, 39, 315.
(23) Bürgi, T.; Urakawa, A.; Behzadi, B.; Ernst, K.-H.; Baiker, A. New J. Chem. 2004, 28, 332.
(24) Martin, R. H.; Marchant, M.-J. Tetrahedron Lett. 1972, 35, 3707.
(25) Flammand-Barbieux, M.; Nasielski, J.; Martin, R. H. Tetrahedron Lett. 1967, 8, 743.
(26) Martin, R. H.; Baes, M. Tetrahedron 1975, 31, 2135.
(27) Wang, Z. Y.; Qi, Y.; Bender, T. P.; Gao, J. P. Macromolecules 1997, 30, 764.
(28) Collins, S. K.; Grandbois, A.; Vachon, M. P.; Côté, J. Angew. Chem. Int. Ed. 2006, 45, 2923.
(29) Teplý, F.; Stará, I. G.; Starý, I.; Kollárovič, A.; Šaman, D.; Rulíšek, L.; Fiedler, P. J. Am.
Chem. Soc. 2002, 124, 9175.
(30) Berthod, M.; Mignani, G.; Woodward, G.; Lemaire, M. Chem. Rev. 2005, 105, 1801.
(31) Gingras, M. Chem. Soc. Rev. 2013, 42, 1051.
(32) Yamamoto, J.; Shibata, T.; Soai, K. Angew. Chem. Int. Ed. 2001, 40, 1096.
(33) Verbiest, T.; Elshocht, S. V.; Kauranen, M.; Hellemans, L.; Snauwaert, J.; Nuckolls, C.;
Katz, T. J.; Persoons, A. Science 1998, 282, 913.
(34) Yang, Y.; da Costa, R. C.; Fuchter, M. J.; Campbell, A. J. Nat. Photonics 2013, 7, 634.
9
(35) Hatakeyama, T.; Hashimoto, S.; Oba, T.; Nakamura, M. J. Am. Chem. Soc. 2012, 134,
19600.
(36) Sahasithiwat, S.; Mophuang, T.; Menbangpung, L.; Kamtonwong, S.; Sooksimuang, T.
Synthetic Metals 2010, 160, 1148.
(37) Shi, L.; Liu, Z.; Dong, G.; Duan, L.; Qiu, Y.; Jia, J.; Guo, W.; Zhao, D.; Cui, D.; Tao, X.
Chem-Eur J. 2012, 18, 8092.

10
Chapter 2. Synthesis and Polymerization of a [5]Helicene Monomer

2.1 Introduction
Although interesting results have been published on the use helicenes in various
applications, these reports have all dealt with helicenes on the molecular level, i.e. small
molecules. The results from these studies have motivated the development of a highly extended
helicene-based structure that would allow for the evaluation of its chiral properties on a larger
scale. Unfortunately, as the number of ortho-fused rings in a helicene increases, so does the
congestion experienced by the molecule as more rings are forced to overlap. Because of this, the
construction of a highly extended helix composed entirely of ortho-fused benzene rings is not
feasible.
Another option for creating a molecule that will allow for the evaluation of chiral
helicenes on the macromolecular level is to incorporate helicenes into a copolymer. If a helicene
molecule is copolymerized along with an aryl “connector,” the resulting alternating structure
could feature both extended conjugation and the helical shape provided by the chiral helicene
monomer. In a few instances helicenes have, in fact, been copolymerized with aryl connectors to
generate helical structures.
1–3
Due to the synthetic challenge posed simply in the preparation of
helicene monomers, the number of reports is not extensive.
4
Hence, there is potential for the
synthesis of new and more effective helicene polymers. Additionally, these reports tend to be for
very specific polymeric structures, without much room for modification as would be desirable for
evaluating their effectiveness as materials in various applications. Still, these efforts inform the
design of new helicene-based materials and shed light on their potential resulting properties.
In 1996, Katz and co-workers reported the first helicene polymer (Scheme 2.1).
3
Here, a
[6]helicene was prepared with functionality capable of reacting with 1,2-phenylenediamine and
11
nickel acetate to produce a structure with extended conjugation. The resulting polymer was
roughly eight helicene units in length, and the helical shape was preserved, as evidenced by the
circular dichroism spectrum. Retention of the sense of helicity was a significant finding and
influenced subsequent polymerization attempts.

Scheme 2.1. Synthesis of a helical conjugated polymer. a) o-phenylenediamine in refluxing
ethanol, followed by Ni(OAc)
2
in refluxing THF and EtOH (95 %). R = CH
2
CH
2
On-Bu.

Two years later, Fox and co-workers published a study in which they compared the effects
of using derivatives of either p- or o-diiodobenzene as the aryl connector in a copolymerization
with an acetylene-functionalized [6]helicene.
2

Scheme 2.2. Helical copolymer prepared from [6]helicene and a para-substituted aryl connector
(R = CON[C
8
H
17
]
2
).
N
N
O
O O
O
N
N
Ni Ni
OR OR
MeO
OMe
OR
MeO
RO
OH HO
O O
MeO
RO
OMe
OR
a
OMe
R
R I
R
R I
n
I
I
R
R
Pd(PPh
3
)
4
, CuI
DIPA, toluene
12

The polymer prepared with the para-substituted aryl connector (Scheme 2.2) showed red-shifted
circular dichroism and UV-Vis spectra when compared with the corresponding monomer spectra.
This indicates that increased conjugation is present in this helicene polymer. However, the
polymer prepared with the ortho-substituted aryl connector gave only a cyclic structure with
significant twisting between the helicene and the aryl groups. The resulting spectra for these
macrocyclic helicenes were very close to the corresponding monomer spectra, and it was
concluded that this structure inhibits π-delocalization. The authors noted that this phenomenon is
analogous to what occurs in binaphthyl-based polymers.

Scheme 2.3. Cyclic polymer prepared from [6]helicene and an ortho-substituted aryl connector
(R = CON[C
8
H
17
]
2
).

During the 1990s, Pu and co-workers synthesized many polymers in which 1,1’-
binaphthalenes (Figure 2.1) were alternated with aryl connectors to produce structures with main-
chain chirality.
5
Enantiopure versions of 1,1’-binaphthalene-based starting materials are readily
R
R
R
R
n
I
R
Pd(PPh
3
)
4
, CuI
DIPA, toluene
R
I
13
available, and from there only a few steps are required to produce monomers with functionality
suitable for undergoing copolymerization with aryl connectors.

Figure 2.1. 1,1’-Binaphthalene.
The synthetic accessibility afforded from the 1,1’-binaphthyl motif has allowed for wide
variability in the functional groups, resulting in a relative ease of tuning the electronic nature of
each unit of the polymer. Among the more interesting results obtained from studies of these
polymers is that they were capable of electroluminescence (as evaluated when incorporated into a
light emitting diode) and SHG.
5
The latter is observed because the binaphthyl groups are
noncentrosymmetric.

Figure 2.2. 1,1’-Binaphthyl-based helical polymer capable of mediating SHG (R = C
18
H
37
).
1
2
3
4 5
6
7
8
1'
2'
3'
4' 5'
6'
7'
8'
O
2
N NO
2
O
2
N NO
2
OR OR OR OR
14

One significant drawback to this work relates to the nature of the 1,1’-binaphthyl unit.
Through comparison of UV-Vis absorption spectra of a polymer and its model repeat units, Pu
demonstrated that there is almost no extended conjugation across the 1,1’-bond in the binaphthyl
units when they are incorporated into the backbone of a polymer.
6
The dihedral angle of 1,1’-
binaphthalene is 68°, and it increases with substitution at the 2- and 2’-positions
7
. The large
dihedral angle between the two naphthalene groups impedes conjugation across this bond (Figure
2.3).

Figure 2.3. R-1,1’-Bi-2-naphthol (BINOL) side (a) and top (b) views.
Unlike 1,1’-binaphthalene, the conjugation in helicene can extend across the entire
molecule.
3
Copolymerizing the latter with an aryl connector can allow for further extension, as
long as that connector does not induce significant twisting (as seen above). However, helicenes
with polymerization potential represent a more synthetically challenging target which has, thus
far, limited the number of polymers with this feature. Hence, simplified synthetic routes toward
helicene-based polymers is a worthy objective.

OH
OH OH
OH
Θ = 80.8°
(a) (b)
15
2.2 Monomer Design
In order for the successful incorporation of a helicene monomer into a polymer, the
helicene must contain reactive functionality. This poses a formidable challenge, as only a handful
of examples of this have been reported.
1–3
It is also important that additional easily modifiable
functional groups are included to allow for tuning of the chemical and/or physical properties of
the helicene. Currently, there are no reports in which a polymerizable helicene meets this
additional constraint.
Initial attempts in our lab toward functionalized helicene monomers featured 1,1’-
binaphthalene or 3,3’,4,4’-tetrahydro-1,1’-binaphthalene intermediates (Scheme 2.4). These
routes proved challenging, with key reactions several steps into either sequence being
unsuccessful.

Scheme 2.4 Unsuccessful attempts toward a helicene monomer (R = alkyl group).
A more successful approach was then developed, inspired by a 2007 report by Kamikawa and co-
workers. The focus of this work was the conversion of Z,Z-stilbenes into helicenes, in one step via
a palladium-mediated C-H arylation reaction (Scheme 2.5).
8

Br
Br
X
OR
OR
Br
Br
OH
OH
X
NR
2
16

Scheme 2.5. Conversion of a Z,Z-stilbene into a [5]helicene via a C-H arylation reaction.
Upon replacement of the fluorine with an acetylene group, this helicene would be capable
of reacting with an aryl halide to generate a fully conjugated polymer under Sonogashira reaction
conditions. This is a very high-yielding carbon-carbon bond forming reaction that has been used
successfully in the preparation of many conjugated polymers,
9,10
including those in which
binaphthyl-based monomers were copolymerized with aryl connectors.
11
While the direct
conversion of aryl fluorides into acetylenes is difficult, a [5]helicene structure featuring a more
reactive halogen (i.e. bromine or iodine) should make this reaction possible. However, it was a
concern that these more reactive halogens react prematurely in the synthetic sequence, as they
would be susceptible to the irreversible oxidative addition of palladium occurring in the first step
of the C-H arylation reaction. This competitive side reaction was envisioned to compete
significantly with formation of the arylation product.
Alternatively, the fluorine could be replaced by chlorine. Although chlorine is much less
reactive than bromine or iodine, Buchwald and co-workers have developed a set of conditions that
allows for this transformation.
12
Aryl chlorides are poor substrates for the C-H arylation reaction
and not expected to compete significantly with the aryl bromide during this reaction.
F
F
MeO
MeO
Br
Br
F
F
MeO
MeO
Pd(II)
86%
17
The methoxy groups on this helicene offer another opportunity for modification. Polymers
composed of helicenes will be at risk for significant π-π interactions that can render a resulting
polymer insoluble in the common organic solvents used for processing and characterization. This
concern can be addressed by including solubilizing groups, such as long alkyl chains.
13
Cleavage
of the methyl ether, followed by alkylation with a longer chain will help to ensure that the
resulting polymer will stay dissolved during its polymerization and subsequent processing.

Figure 2.4. Target helicene monomer (R = 2-ethylhexyl).
Additionally, the methoxy functional group serves as an electron-donor (D). The general
D-π-A (where π is a conjugated linker, and A is an electron-acceptor) structure has been
determined to be most effective for chromophores in polymers capable of mediating nonlinear
optical processes.
14
These processes depend on the hyperpolarizability of the chromophores, and
the ability to tune the electronic structure through the modification of these groups allows for
optimization of the hyperpolarizability. An aryl group functionalized with A groups and then
polymerized with a D-containing helicene could give an extended structure of these D-π-A units.
In addition, the methoxy group can be replaced or modified for further tuning of electronic
properties.

RO
RO
2.1
18

Scheme 2.6. Simplified depiction of the preparation of a helicene-based copolymer with electron
acceptor (A) and electron donor (D) groups (X = halogen).

Having considered the possibilities for modification, a route toward 2.1 was developed. It
should be noted, however, that the racemization barrier for [5]helicene (24.1 kcal/mol at 27 °C)
15

is low enough that it racemizes at room temperature within a few hours.
16
Because of this, the
synthesis of a [5]helicene-based chiral polymer is not the main objective, but rather, a
demonstration of a viable synthetic route toward this goal. Strategies for increasing the
racemization barrier through synthesis will be discussed below.

2.3 Synthesis of a [5]Helicene Monomer
The synthesis of this target structure (2.1) begins with the assembly of a Z,Z-stilbene,
which is the substrate for the C-H arylation reaction. The Z,Z stereochemistry is preferred,
because this isomer will allow the carbon atoms participating in bond-formation to be in close
proximity. As mentioned in the previous section, the fluorine atoms from the stilbene prepared by
Kamikawa and co-workers need to be replaced with chlorine atoms in order to ultimately
functionalize the helicene with acetylene groups. It is important to consider what effect (if any)
this change will have on the stereochemistry of the stilbene.
D
D
A
A
n
D
D
A
X
X
A
+
polymerization
19
In a separate study by Dunne and co-workers on the effects of ortho-substituents on the
stereochemical outcome of the Wittig reaction, it was determined that the ratio of Z to E alkenes
was highest when both the aldehyde and the triphenylphosphine salt contained a single ortho-
substituent relative to the reactive functionality.
17
This preference is more strongly affected by the
substituent on the aldehyde. The interaction between this substituent and the phosphorus of the
salt are shown in Figure 2.5.

Figure 2.5. Bonding of an o-methoxy substituent with phosphorus in (a) the cis-OPA and (b) the
trans-OPA.

This interaction can be accommodated by puckering of the oxaphosphetane (OPA) intermediate,
which stabilizes the cis-OPA by reducing unfavorable 1,2-interactions.
17
The authors proposed
that an ortho-substituent on the salt would contribute to the steric interactions in the trans-OPA
more so than in the cis-OPA, thereby enhancing Z-selectivity. The fluorine is meta in relation to
the triphenylphosphine group (Scheme 2.7), and does not contribute significantly to the observed
stereochemistry. Indeed, the desired stereochemistry in stilbenes prepared by Kamikawa was
achieved, as expected, through mono-ortho-substitution of the aryl rings of the two reaction
partners.
8
Hence, replacement of fluorine with chlorine is not expected to cause the desired Z-
selectivity to diminish to an appreciable extent.
O
P
O
O
O
H
Ph O
P
O
O
O
H
H
H Ph
Ph
Ph
Ph
Ph
Ph
Ph
(a) (b)
20

Scheme 2.7. Z,Z-selective preparation of a stilbene substrate for C-H arylation.
A chlorinated derivative of 2.2 was synthesized by, first, selecting a phenyl group with the
appropriate substitution as a precursor to the triphenylphosphine salt. This compound (2.5) is
commercially available and was reacted with triphenylphosphine to afford the corresponding salt
(2.6) in near quantitative yield.
18,19

Scheme 2.8. Preparation of the triphenylphosphine salt.
No deviations from the structure of the dialdehyde (2.3) used by Kamikawa were
necessary, and it was prepared according to previous reports, via double directed ortho-lithiation
of veratrole (2.7).
20

Br
Br
F
F
MeO
MeO
MeO
MeO
O
O
H
H
F
PPh
3
Br
Br
+ (2)
KOt-Bu
54%
Z,Z : Z,E = 7:1
2.2
2.3 2.4
Cl
Br
Br
Cl
PPh
3
Br
Br
PPh
3
, DMF
reflux, 3 h
98%
2.6 2.5
21

Scheme 2.9. Preparation of the dialdehyde.
The regiochemistry of the product is due to directed ortho metalation (DOM).
21
As depicted in
Scheme 2.10, coordination between lithium and oxygen lead to preferential deprotonation at the
positions ortho to methoxy functionality and to formation of an aryllithium species. DMF acts as
an electrophile in a subsequent electrophilic aromatic substitution, generating dialdehyde 2.3 upon
workup. The relatively low yield of this reaction (34%) was likely due to the reduced solubility of
the aryllithium intermediate.
21
After the first lithiation the resulting species tended to precipitate,
making the second lithiation difficult.

Scheme 2.10. Simplified depiction of DOM leading to the observed regiochemistry of the
dialdehyde.

With both aldehyde 2.3 and triphenylphosphine salt 2.6 in hand, the two were combined
under basic conditions to generate Z,Z-stilbene 2.9 (Scheme 2.11).
8

MeO
MeO
MeO
MeO
O
O
H
H
1. n-BuLi, TMEDA, DEE
-78 °C to reflux, 16 h
2. DMF, -78 °C to rt, 1 h
34%
2.3
2.7
MeO
MeO
MeO
MeO
MeO
MeO
O
O
H
H
n-BuLi
DMF
Li
Li
2.7 2.3 2.8
22

Scheme 2.11. Preparation of the Z,Z-stilbene via a Wittig reaction.
a
Isolated yield of the Z,Z
isomer.

A comparison of the coupling constants for the major product in this reaction with coupling
constants for the previously reported compounds supported the assignment of Z,Z stereochemistry
to the major isomer (6:1 Z,Z:Z,E). This Z,Z:Z,E ratio is similar to that previously obtained for the
fluorinated version (Scheme 2.7).
8

The subsequent conversion of stilbene 2.9 into a [5]helicene was accomplished via a
palladium-catalyzed double C-H arylation reaction. The conditions used here were similar to
those used to prepare the analogous fluorinated compound.
8
In our case the reaction temperature
was decreased by 10 °C in order to reduce the oxidative addition of palladium into the carbon-
chlorine bond.
22
Upon completion of this reaction and very careful chromatographic separation,
the desired product (2.10) was obtained in 63% yield.

Br
Br
Cl
Cl
MeO
MeO
MeO
MeO
O
O
H
H
Cl
PPh
3
Br
Br
KOt-Bu, THF:H
2
O (10:1)
0 °C to rt, 30 min
68%
a
Z,Z : Z,E = 6:1
+ (2)
2.3
2.6 2.9
23

Scheme 2.12. Palladium-mediated double C-H arylation reaction.
This helicene derivative has limited solubility in common organic solvents (DCM, THF,
and ACN). Because it is important that a polymer composed from helicenes be soluble in the
organic solvents to be used in processing, the decision was made to functionalize 2.10 with two 2-
ethylhexyl groups.
23
Installation of the 2-ethylhexyl groups was achieved by, first, cleavage of the
methoxy ether functionality using boron tribromide.
24,25
The resulting diol (2.11) was
subsequently alkylated with 2-ethylhexyl bromide. This reaction proceeded slowly, but with the
inclusion of dibenzo-18-crown-6 as a catalyst, a moderate yield (38%) of the alkylated product
(2.12) was obtained as a viscous oil.
26
Compound 2.12 was significantly more soluble in common
organic solvents in comparison with its predecessor (2.10).

Scheme 2.13. Deprotection of the methoxy groups, followed by alkylation (R = 2-ethylhexyl).
Br
Br
Cl
Cl
MeO
MeO
Cl
Cl
MeO
MeO
20 mol% Pd(OAc)
2
40 mol% PCy
3
·HBF
4
K
2
CO
3
, Ag
2
CO
3
DMA, 120 °C, 16 h
63%
2.9
2.10
Cl
Cl
MeO
MeO
Cl
Cl
HO
HO
Cl
Cl
RO
RO
Br
BBr
3
, DCM
-78 °C to °0 C, 5 h
57%
dibenzo-18-crown-6
K
2
CO
3

DMF, 90 °C, 48 h
38%
2.10 2.11 2.12
24
The remaining task for completing this monomer was the addition of the alkyne groups
that will allow this monomer to participate in a polymerization reaction. Using the method
reported by Buchwald,
12
two TIPS-protected acetylene groups were added to the helicene
(Scheme 2.14). In this case, doubling the ratio of ligand to metal (6:1 rather than 3:1) was
necessary for optimal yields. Deprotection of the TIPS groups was accomplished with
tetrabutylammonium fluoride.
27
This reaction proceeded without incident, thus completing the
synthesis of the target compound (2.1).

Scheme 2.14. Insertion of the TIPS-protected alkyne groups, followed by deprotection of the
TIPS groups (R = 2-ethylhexyl).

Cl
Cl
RO
RO
RO
RO
RO
RO
TIPS
TIPS
TIPS
4 mol% PdCl
2
(CH
2
CN)
2
24 mol% XPhos, Cs
2
CO
3
1,4-dioxane, 90 °C, 16 h
80%
TBAF, THF
0 °C to rt, 16 h
96%
XPhos =
PCy
2
i-Pr
i-Pr
i-Pr
2.12
2.13
2.1
25
2.4 Polymerization of a [5]Helicene Monomer
In order to demonstrate that this pathway is successful in producing a viable monomer, 2.1
was subjected to a step polymerization with p-diiodobenzene. The selection of the p-
diiodobenzene was intended to maximize the distance between neighboring helicenes in order to
allow for extended conjugation along the polymer backbone. Figure 2.6 shows a simplified
model of three polymer units. We believe that the aryl co-monomer will allow sufficient spacing
between the helicenes to prevent kinking.

Figure 2.6. Ball-and-stick model of three units of a copolymer composed of acetylene-
functionalized [5]helicene and p-diiodobenzene. This model is color-coded for depth, with atoms
closer to the reader in red and further away in blue.

Additionally, a model compound (2.14) was prepared
9
so that the properties of the polymer could
be compared with those of a simpler molecule (Scheme 2.15).
26

Scheme 2.15. Preparation of a model monomer (R = 2-ethylhexyl).
Polymerization was accomplished by a palladium-catalyzed Sonogashira reaction of 2.1
and p-diiodobenzene in the presence of catalytic amounts of Pd(PPh
3
)
4
Cl and CuI to afford
polymer 2.15 in 80% yield.
9
This polymer was soluble in common organic solvents, including
THF, DCM, and CHCl
3
. The number-average molecular weight (M
n
) was determined to be 4,411
g/mol (PDI = 1.48) by SEC, using polystyrene standards in THF.
28,29

Scheme 2.16. Polymerization between the helicene monomer and p-diiodobenzene
(R = 2-ethylhexyl).

As shown in Figure 2.7, the absorption maxima at 286, 348, and 382 nm of polymer 2.15
are red-shifted compared with model monomer 2.14 having maxima at 283, 332, and 372 nm,
with red shifts of 3, 16, and 12 nm, respectively. These spectral differences are consistent with the
extended conjugation of the π structure.
30
This finding is significant, because extended
RO
RO
RO
RO
Pd(PPh
3
)
4
Cl, CuI
TEA, THF
40 °C, 16 h
I
+
2.1 2.14
(2)
RO
RO
n
RO
RO I
I
+
Pd(PPh
3
)
4
Cl, CuI
TEA, THF
40 °C, 48 h
80%
2.1 2.15
27
conjugation is a desired characteristic in the design of many organic materials.
31
As discussed
earlier, extended conjugation is absent from polymers composed of 1,1’-binaphthyl moieties,
because the large degree of twisting around the single bond connecting the two naphthalenes
impedes the overlap of π-orbitals.
6
For the helicene moiety in 2.15, this twisting is absent, and
conjugation may continue along the polymer chain.
32

Figure 2.7. Normalized absorption spectra of model monomer 2.14 (332 nm, ε = 49,900 L mol
-1

cm
-1
) and polymer 2.15 (348 nm, ε = 85,100 L mol
-1
cm
-1
) in CHCl
3
at 25 °C.

2.5 Resolution
With the preparation of a [5]helicene monomer, it was demonstrated that this molecule is
capable of participating in a polymerization reaction to form a macromolecule. Ultimately, it
would be desirable for an enantiopure helicene of this type to be incorporated in a polymer as
well. Hence, an effort was made to resolve the helicene monomer.
With chirality being the key feature of interest for the helicenes, many methods for the
stereoselective preparation and resolution of these molecules have been reported.
33
The inclusion
0

0.2

0.4

0.6

0.8

1

240
290
340
390
440

Normalized
Intensity

Wavelength
(nm)

Polymer

Monomer

28
of a chiral auxiliary has been successful in synthesizing helicene diastereomers that can be
separated by flash chromatography (Figure 2.8).
2
For this to work, however, the chiral group
needs to be positioned at the 1- or 2-position (the “bay area”) of the molecule.

Figure 2.8. [6]Helicene with menthyl chiral auxiliaries at positions 2 and 15. These diastereomers
can be separated by column chromatography.

Previous studies have shown that when the chiral auxiliary is positioned further away from the
helical core (as in Figure 2.9), it does not induce enough of a difference between the
diastereomers for them to be separated by column chromatography or recrystallization.
34

Figure 2.9. [6]Helicene with camphanic chiral auxiliaries at positions 3 and 14. These
diastereomers are inseparable by either column chromatography or recrystallization.

O
O
O
O
CH
3
H
3
C
O
O
O
O
O
O
O
O
29
If reaction with a chiral auxiliary were to be used to resolve the [5]helicene, the simplest
point along the route to attempt this would be following the formation of the diol (2.11), allowing
the free hydroxyls to participate in an esterification. Unfortunately, the oxygen atoms on this
molecule are located at positions 7 and 8, and this resolution method is not expected to be
successful.

Figure 2.10. Helicene diol, a precursor to the monomer.
Another extensively used separation technique for helicenes is chiral HPLC, which has
been successfully utilized in the separation of helicenes ranging in size from [5]- to [14]helicene,
both functionalized and unfunctionalized. The first example of this type of chiral separation of
unfunctionalized [6]helicenes utilized S(+)-TAPA (10-25 wt%) coated on silica gel as the chiral
stationary phase.
35
Since then, many other chiral stationary phases, both prepared in the
laboratory and purchased from commercial sources, have been used successfully.
36

Figure 2.11. S(+)-2-(2,4,5,7-tetranitro-9-fluorenylidene-aminooxy) propionic acid (TAPA).
Cl
Cl
HO
HO
2.11
NO
2
NO
2
NO
2
O
2
N
N
O
CO
2
H
H
3
C
H
30

With this in mind, chiral HPLC appeared to be a more appropriate method for the
resolution of 2.11. Accordingly, a racemic sample of the diol was injected into an HPLC setup
with an AD-H (chiral) column employing ACN as the eluent, and nearly complete separation of
the two enantiomers was observed. Having demonstrated that a helicene with this structure can be
separated with this method is valuable to keep in mind as other helicenes of this type with
additional rings are prepared. Notably, it has been shown that the ease of resolution increases with
an increase in the size of the helicene.
37
Hence, this set of conditions can be used as a starting
point for the resolution of larger helicenes. Finally, the ability to resolve the diol is advantageous
in the context of developing a more efficient synthetic sequence, as the resolved product can
subsequently be alkylated with any desirable group, not just 2-ethylhexyl, which should allow for
greater flexibility with respect to the final monomer structure.

31
2.6 References
(1) Takahira, Y.; Sugiura, H.; Yamaguchi, M. J. Org. Chem. 2006, 71, 763.
(2) Fox, J. M.; Lin, D.; Itagaki, Y.; Fujita, T. J. Org. Chem. 1998, 63, 2031.
(3) Dai, Y.; Katz, T. J.; Nichols, D. A. Angew. Chem. Int. Ed. 1996, 35, 2109.
(4) Gingras, M. Chem. Soc. Rev. 2013, 42, 1051.
(5) Pu, L. Macromol. Rapid Commun. 2000, 21, 795.
(6) Pu, L. Chem. Rev. 1998, 98, 2405.
(7) Shockravi, A.; Javadi, A.; Abouzari-Lotf, E. RSC Adv. 2013, 3, 6717.
(8) Kamikawa, K.; Takemoto, I.; Takemoto, S.; Matsuzaka, H. J. Org. Chem. 2007, 72, 7406.
(9) Yuan, W. Z.; Hu, R.; Lam, J. W. Y.; Xie, N.; Jim, C. K. W.; Tang, B. Z. Chem-Eur J. 2012,
18, 2847.
(10) Kondo, K.; Okuda, M.; Fujitani, T. Macromolecules 1993, 26, 7382.
(11) Cheng, Y.; Song, J.; Zou, X.; Zhang, S.; Liu, Y.; Huang, H. Polymer 2006, 47, 6598.
(12) Gelman, D.; Buchwald, S. L. Angew. Chem. Int. Ed. 2003, 42, 5993.
(13) Ma, L.; Hu, Q.-S.; Musick, K. Y.; Vitharana, D.; Wu, C.; Pu, L. Macromolecules 1996, 29,
5083.
(14) Dalton, L. In Polymers for Photonics Applications I; Advances in Polymer Science; Springer
Berlin Heidelberg, 2002; pp. 1–86.
(15) Martin, R. H.; Marchant, M. J. Tetrahedron 1974, 30, 347.
(16) Stammel, C.; Fröhlich, R.; Wolff, C.; Wenck, H.; de Meijere, A.; Mattay, J. Eur. J. Org.
Chem. 1999, 1999, 1709.
(17) Dunne, E. C. Pergamon Tetrahedron Lett. 2002, 43, 2449.
(18) John Plater, M. J. Chem. Soc. Perkin 1 1997, 2903.
(19) Caruso, A.; Siegler, M. A.; Tovar, J. D. Angew. Chem. Int. Ed. 2010, 49, 4213.
(20) Kuhnert, N.; Rossignolo, G. M.; Lopez-Periago, A. Org. Biomol. Chem. 2003, 1, 1157.
(21) Crowther, G. P.; Sundberg, R. J.; Sarpeshkar, A. M. J. Org. Chem. 1984, 49, 4657.
(22) Roy, A. H.; Hartwig, J. F. J. Am. Chem. Soc. 2001, 123, 1232.
(23) Padmanaban, G.; Ramakrishnan, S. J. Am. Chem. Soc. 2000, 122, 2244.
(24) Nakajima, M.; Miyoshi, I.; Kanayama, K.; Hashimoto, S.-I. J. Org. Chem. 1999, 64, 2264.
(25) Bandind, M.; Casolari, S.; Cozzi, P. G.; Proni, G.; Schmohel, E.; Spada, G. P.; Tagliavini,
E.; Umani-Ronchi, A. Eur. J. Org. Chem. 2000, 2000, 491.
(26) Howard, M. J.; Heirtzler, F. R.; Dias, S. I. G. J. Org. Chem. 2008, 73, 2548.
(27) Wipf, P.; Graham, T. H. J. Am. Chem. Soc. 2004, 126, 15346.
(28) Kokado, K.; Tokoro, Y.; Chujo, Y. Macromolecules 2009, 42, 9238.
(29) Cheng, H.; Pu, L. Macromol. Chem. Phys. 1999.
(30) Bédard, A.-C.; Vlassova, A.; Hernandez-Perez, A. C.; Bessette, A.; Hanan, G. S.; Heuft, M.
A.; Collins, S. K. Chem-Eur J. 2013, 19, 16295.
(31) Bendikov, M.; Wudl, F.; Perepichka, D. F. Chem. Rev. 2004, 104, 4891.
(32) Shen, Y.; Chen, C.-F. Chem. Rev. 2012, 112, 1463.
(33) Gingras, M.; Félix, G.; Peresutti, R. Chem. Soc. Rev. 2013, 42, 1007.
(34) Aloui, F.; El Abed, R.; Marinetti, A.; Ben Hassine, B. C. R. Chim. 2009, 12, 284.
(35) Mikeš, F.; Boshart, G.; Gil-Av, E. J. Chem. Soc. Chem. Commun. 1976.
(36) Aloui, F.; Abed, R. E.; Marinetti, A.; Hassine, B. B. Tetrahedron Lett. 2008, 49, 4092.
(37) Mikeš, F.; Boshart, G.; Gil-Av, E. J. Chromatogr. 1976, 122, 205.
32
Chapter 3. Progress Toward a [6]Helicene Monomer

3.1 Introduction
Having demonstrated a successful route toward a [5]helicene monomer and its
polymerization, the next objective was to prepare a [6]helicene monomer able to retain its
conformation and hence chirality, during and beyond its polymerization. For optoelectronic
applications, the lower limit for the free energy barrier to racemization is on the order of 35 kcal
mol
-1
.
1
Unfunctionalized [6]helicene has a racemization barrier of 36.2 kcal mol
-1
(27 °C),
2
with
evidence of only partial racemization at its melting point of 266 °C.
3

The introduction of another ring poses an additional synthetic challenge, but this goal can
be met by following a route analogous to the one followed to prepare the [5]helicene. However,
there is a key difference. Rather than preparing a stilbene flanked with two substituted benzenes,
the stilbene must feature one substituted benzene and one substituted naphthalene. To prepare a
stilbene that is asymmetrical, the Wittig reaction must be carried out sequentially. The precursor
dialdehyde must first be reacted with a benzene-based triphenylphosphine salt, followed by
reaction with a naphthalene-based triphenylphosphine salt.
There is a report of this modification by the same group that reported the use of the double
C-H arylation reaction for the preparation of [5]helicenes (although, due to the increased
crowding, a decrease in yield was observed) (Scheme 3.1).
4
Hence, the desired monomer can be
prepared without deviating significantly from the synthesis of the [5]helicene. The same
dialdehyde (2.3) and benzyl phosphonium salt (2.6) can still be used, but an additional
naphthalene phosphonium precursor is required.

33

Scheme 3.1. Formation of a [6]helicene via a double C-H arylation reaction.
The required naphthalene structure (Figure 3.1) was selected such that the resulting
[6]helicene would have a structure similar to that of the [5]helicene. Although this exact
naphthalene (3.1) has not been reported, the design is based on the structure of analogous
naphthalene derivatives (3.2 and 3.3) synthesized by Furukawa and co-workers.
5

Figure 3.1. Target naphthalene (3.1) for the preparation of a [6]helicene, and previously reported
naphthalenes prepared by Furukawa (3.2 and 3.3).

3.2 Synthesis of a [6]Helicene Monomer

The synthesis of 3.1 began with the conversion of commercially available 6-amino-1-
tetralone into aryl chloride 3.5, as reported by Cui and co-workers.
6
This chlorinated tetralone
underwent a Vilsmeier-Haack type reaction to produce 3.6.
5
Aromatization to produce
naphthalene 3.7 was accomplished with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Ten
equivalents of this reagent were required for complete oxidation. This was followed by reduction
of the aldehyde under Wolff-Kishner conditions to afford 3.1 in good yield.

MeO
MeO
Br
Br
Pd(II)
30%
MeO
MeO
Cl
Br Br Br
3.1 3.2 3.3
Cl
Cl
34

Scheme 3.2. Preparation of the desired naphthalene.
The formation of the naphthalene ylide precursor, 3.9, involved two steps, beginning with
bromination of 3.1 at the benzylic position to give 3.8.
7
The use of a less-than-stoichiometric
amount of brominating agent NBS suppressed the formation of the undesired dibrominated
product. Addition of triphenylphosphine
8
completed the synthesis of 3.9 in excellent yield.

Scheme 3.3. Preparation of the naphthalene-based triphenylphosphine salt.
The sequential assembly of stilbene 3.10 began with the Wittig reaction of dialdehyde 2.3
with one equivalent of 2.6. After separation from a small amount of unreacted dialdehyde, a
second Wittig reaction with 3.9 then afforded 3.10 in 64% isolated yield. The naphthalene salt
was intentionally reacted in the second step to maximize the incorporation of this synthetically
expensive material into 3.10.

H
2
N
O
Cl
O
NaNO
2
, HCl, CuCl
-10 °C to rt, 2 h
84%
3.4 3.5
Cl
Br O
H
Cl
Br O
H
Cl
Br
3.6
1. PBr
3
, DMF
DCM, 0 °C, 2 h
2. 3.5, DCM
0 °C to reflux, 16 h
64%
DDQ, toluene
reflux, 16 h
52%
KOH, TEG
NH
2
NH
2
•H
2
O
0 °C to 180 °C, 2 h
84%
3.6
3.7 3.1
Cl
Br
Cl
Br
Br
Cl
Br
PPh
3
Br
NBS, BPO
CCl
4
, reflux, 16 h
80%
PPh
3
, DMF
reflux, 3 h
97%
3.1 3.8 3.9
35

Scheme 3.4. Stepwise preparation of the asymmetrical Z,Z-stilbene.
Upon double C-H arylation of stilbene 3.10, the desired [6]helicene (3.11) was formed in
much lower yield than less-crowded [5]helicene 2.10. Additionally, a mix of single C-H arylation
products and those in which bromine was eliminated without forming a new C-C bond were
formed.
4
The desired [6]helicene derivative was then subjected to demethylation under the
conditions used previously to prepare the [5]helicene diol.
9

Scheme 3.5. C-H arylation to form the [6]helicene and subsequent demethylation.
As the previously synthesized [5]helicene diol 2.7 could be resolved on a chiral HPLC
column, it is expected that this [6]helicene diol can be, as well.
10
Should this resolution take
place, the remaining steps to complete a [6]helicene monomer should be relatively
straightforward, as it is expected that the same conditions optimized for preparation of the
[5]helicene monomer can be applied directly complete to the [6]helicene monomer. With
enantiopure [6]helicene in hand, a copolymerization with an aryl connector should result in a
uniform helical polymer.
H O
O H
MeO
MeO
MeO
MeO
Br
Cl
Br
Cl
Br
Cl
PPh
3
Br
+
1. KOt-Bu, THF:H
2
O (10:1)
0 °C to rt, 30 min
2. 3.9, KOt-Bu, THF:H
2
O (10:1)
0 °C to rt, 30 min
64%
2.6 2.3
3.10
3.10
20 mol% Pd(OAc)
2
40 mol% PCy
3
·HBF
4
K
2
CO
3
, Ag
2
CO
3
DMA, 120 °C, 16 h
11%
BBr
3
, DCM
-78 °C to °0 C, 5 h
65%
3.11 3.12
MeO
MeO
Cl
Cl
HO
HO
Cl
Cl
36
3.3 References
(1) Rajca, A.; Miyasaka, M. In Functional Organic Materials. Syntheses, Strategies, and
Applications; Müller, T. J. J.; Bunz, U. H. F., Eds.; Wiley-VCH, 2007; pp. 547–581.
(2) Martin, R. H.; Marchant, M. J. Tetrahedron 1974, 30, 347.
(3) Newman, M. S.; Lednicer, D. J. Am. Chem. Soc. 1956, 78, 4765.
(4) Kamikawa, K.; Takemoto, I.; Takemoto, S.; Matsuzaka, H. J. Org. Chem. 2007, 72, 7406.
(5) Furukawa, A.; Arita, T.; Fukuzaki, T.; Mori, M.; Honda, T.; Satoh, S.; Matsui, Y.;
Wakabayashi, K.; Hayashi, S.; Nakamura, K.; Araki, K.; Kuroha, M.; Tanaka, J.; Wakimoto,
S.; Suzuki, O.; Ohsumi, J. Eur. J. Med. Chem. 2012, 54, 522.
(6) Cui, L.-Q.; Dong, Z.-L.; Liu, K.; Zhang, C. Org. Lett. 2011, 13, 6488.
(7) Imoto, M.; Ikeda, H.; Fujii, T.; Taniguchi, H.; Tamaki, A.; Takeda, M.; Mizuno, K. Org.
Lett. 2010, 12, 1940.
(8) Caruso, A.; Siegler, M. A.; Tovar, J. D. Angew. Chem. Int. Ed. 2010, 49, 4213.
(9) Nakajima, M.; Miyoshi, I.; Kanayama, K.; Hashimoto, S.-I. J. Org. Chem. 1999, 64, 2264.
(10) Mikeš, F.; Boshart, G.; Gil-Av, E. J. Chromatogr. 1976, 122, 205.

37
Chapter 4. Conclusions

4.1 Summary of the Thesis
An alkyne-functionalized [5]helicene with electron-donating functionality was prepared
and copolymerized with an aryl connector with potentially variable functionality to produce a
polymer with extended conjugation. Finding a successful route toward this goal was challenging
and required several attempts. This is the first example of a polymerization of a helicene with
modifiable electron-donating functionality. This variability opens up helicenes as potential
tunable components in organic electronic materials.
The progress made toward a [6]helicene monomer demonstrated that a helicene with the
desired conformational stability can be prepared. Additionally, it showed that the reactions
developed for the [5]helicene monomer are applicable to the synthesis of [6]helicenes. A polymer
prepared from an enantiomerically pure helicene of this type should possess a uniform helical
sense in its backbone.
This chemistry is intended to mediate the exploration of helicenes in the development of
improved chiral materials for liquid crystal displays, organic light-emitting diodes, and nonlinear
optical materials.

38
4.2 Future Work
Preparation of the [6]helicene diol indicated that a conjugated, helical monomer with what
is likely to be a high barrier to racemization could be fabricated. The double C-H arylation
reaction of a naphthalene-functionalized stilbene was utilized because of precedents in the
literature. However, the racemization barrier of a [5]helicene can be increased through other
synthetic strategies. For example, the inclusion of a methyl group at the 1-position has been
shown to increase the conformational stability of a given helicene with an effect similar to that of
an additional ortho-fused aromatic ring.
1

For instance, the route presented for the [5]helicene monomer can be modified to feature
methyl groups at the 1- and 14-positions
2
with the addition of a single step at the beginning of the
sequence. Bromination of one of the two equivalent methyl groups on commercially available 4.1
would generate a benzyl bromide which could then be converted into a triphenylphosphine salt.

Scheme 4.1. Possible route toward the preparation of a new triphenylphosphine salt.
Two equivalents of this salt could be reacted with the same dialdehyde (2.3) as featured
previously to afford a symmetrical Z,Z-stilbene (Scheme 4.2).

Cl
Br
Cl
Br
Br
Cl
Br
PPh
3
Br
NBS
PPh
3
4.1 4.2 4.3
39

Scheme 4.2. Preparation of a possible dimethylated Z,Z-stilbene.
This Z,Z-stilbene could then be submitted to the double C-H arylation reaction. The desired
product of this reaction would be a C
2
-symmetric [5]helicene with an improved barrier to
racemization. The route toward this monomer is simpler than that for the [6]helicene monomer,
making it feasible as an alternate target structure.
2

Scheme 4.3. Synthesis of a new alkyne-functionalized helicene with methyl groups at the 1- and
14-positions (R = alkyl group).

Either the [6]helicene or the methylated [5]helicene can be copolymerized with an aryl
connector to generate a helical structure. With one-step procedures,
3–5
that aryl connector can be
functionalized with electron-withdrawing functionality (Figure 4.1) to generate an enhanced
push-pull electronic effect across each polymer unit. Through this complementary synthetic
strategy, the ultimate goal of preparing a chiral helicene-based polymer may be realized.
Br
Br
Cl
Cl
MeO
MeO
4.4
Cl
Br
PPh
3
Br
MeO
MeO
O
O
H
H
(2) +
KOt-Bu
4.3 2.3
Br
Br
Cl
Cl
MeO
MeO
MeO
MeO
RO
RO
Cl
Cl
Pd(II)
40

Figure 4.1. Electron-withdrawing aryl connectors that can be prepared in one step from
commercially available starting materials.

NO
2
I I I
I
NO
2
I
I
NO
2
NO
2
4.5 4.6
4.7
41
4.3 References
(1) Janke, R. H.; Haufe, G.; Wurthwein, E.-U.; Borkent, J. H. J. Am. Chem. Soc. 1996, 118,
6031.
(2) Minuti, L.; Taticchi, A.; Marrocchi, A.; Gacs-Baitz, E.; Galeazzi, R. Eur. J. Org. Chem.
1999, 1999, 3155.
(3) Zimcik, P.; Miletin, M.; Radilova, H.; Novakova, V.; Kopecky, K.; Svec, J.; Rudolf, E.
Photochem. Photobiol. 2009, 86, 168.
(4) Görl, C.; Beck, N.; Kleiber, K.; Alt, H. G. J. Mol. Catal. A Chem. 2012, 352, 110.
(5) Sapountzis, I.; Dube, H.; Lewis, R.; Gommermann, N.; Knochel, P. J. Org. Chem. 2005, 70,
2445.

42
Chapter 5. Experimental and Spectral Data

5.1 General Procedures
All reactions, unless otherwise noted, were conducted using commercially available
solvents and reagents as received, without additional purification, in ordinary glassware under an
inert argon atmosphere. Veratrole and TEA were distilled after being stirred over CaH
2
for several
hours. Dry solvents, such as: DCM, DMF, and THF were obtained from a DriSolv® bottle.
1
H
and
13
C NMR spectra were recorded on Mercury 400 or Varian 400-MR (400 MHz) NMR
spectrometers, using residual
1
H or
13
C signals of deuterated solvents as internal reference
standards. Reactions were monitored by TLC carried out on 0.200 mm analytical layer Baker-
flex® plates using UV light (254 nm) as the visualizing agent. Silica gel (60 Å, 40-63 µm; Alfa
Aesar) was used as a sorbent for flash column chromatography.
SEC was performed on a Shimadzu HPLC system consisting of: a Shimadzu LC-20AT
HPLC pump, a Rheodyne 7725i injector, Phenogel 5u 50 x 7.8 mm Guard Column, Polymer
Laboratories PLgel 5 µm MIXED-C column x 2, and a Shimadzu RID 10-A detector, at ambient
temperature, using THF (HPLC grade) as the elution solvent with a flow rate of 1 ml/min.
Polystyrene standards were used for calibration.
The absorbance spectra were recorded on an Agilent UV-Visible Spectrophotometer using
a 1 cm trajectory and a blank cell (CHCl
3
) for each sample. Monomer 2.1 (4.4 mg) was dissolved
in 5 ml of CHCl
3
to make a stock solution (3.69x10
-4
M), which was then diluted to achieve an
appropriate concentration for measurement (1.42x10
-5
M). Model monomer 2.14 (1.6 mg) was
dissolved in 4 ml of CHCl
3
to make a stock solution (5.45x10
-4
M), which was then diluted to
achieve an appropriate concentration for measurement (4.95x10
-5
M). Polymer 2.15 (0.4 mg) was
43
dissolved in 4 ml of CHCl
3
to make a stock solution (2.01x10
-5
M), which was then diluted to
achieve an appropriate concentration for measurement (1.82x10
-6
M).
HPLC analysis was carried out on a Shimadzu LC-6AD system with a ChiralPak AD-H
column. ACN comprised the mobile phase at a flow rate of 0.8 ml/min, and a UV detector set at
220 nm was used to determine elution time.

44
5.2 Chapter 2 Experimental and Spectral Data

2,3-Dimethoxy-1,4-dicarbaldehyde (2.3)

TMEDA (37.5 ml, .250 mol) was added to a solution of veratrole (6.37 ml, .0500 mol) in
DEE (250 ml).
3
The reaction mixture was cooled to -78 °C, and n-butyllithium 2.5 M in hexanes
(100 ml, .250 mol) was added over 10 min. The solution was allowed to warm to rt, heated to
reflux, and allowed to stir for 16 h. The solution was then cooled to -78 °C for the addition of
DMF (19.3 mL, 0.250 mol), followed by warming to rt and stirring for 4 h. Finally, the 200 ml of
water was added, followed by the addition of 3 M HCl to neutralize the solution. The organic
layer was separated and the aqueous layer was extracted using three 500 ml portions of DEE. The
combined organic layers were washed with saturated aqueous NaHCO
3
, water, and brine,
followed by drying over Na
2
SO
4
and concentration under reduced pressure. Purification by flash
column chromatography using 25% EtOAc/hexanes as eluent, followed by recrystallization from
10% toluene/hexanes afforded a pale yellow solid (3.31 g, 34%). TLC: 25% EtOAc/hexanes, R
f

≈ 0.5. Mp 98-100 °C.
1
H NMR (400 MHz, CDCl
3
) δ 10.44 (s, 2H), 7.62 (s, 2H), 4.05 (s, 6H).
13
C
NMR (101 MHz, CDCl
3
) δ 189.37, 156.79, 134.36, 122.98, 62.61.

MeO
MeO
O
O
H
H
45

1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

46
(2-Bromo-5-chlorobenzyl)triphenylphosphonium bromide (2.6)

1-Bromo-2-(bromomethyl)-4-chlorobenzene (2.50 g, 8.79 mmol) and triphenylphosphine
(2.31 g, 8.79 mmol) were brought up in DMF (9 ml) and allowed to stir at reflux for 3 h.
1,2
The
mixture was allowed to cool to rt and filtered to collect the product which was washed with cold
toluene, followed by cold hexanes. The product was obtained as a colorless solid (4.73 g, 98%).
Mp > 250 °C.
1
H NMR (400 MHz, CDCl
3
) δ 7.85 – 7.50 (m, 15H), 7.47 (q, J = 2.6 Hz, 1H), 7.30
(d, J = 8.5 Hz, 1H), 7.11 (dt, J = 8.8, 2.6 Hz, 1H), 5.83 (d, J = 15.0 Hz, 2H).
13
C NMR (101 MHz,
CDCl
3
) δ 135.39 (d, J
PC
= 3.1 Hz), 134.53 (d, J
PC
= 10.0 Hz), 133.95 (d, J
PC
= 3.4 Hz), 133.04 (d,
J
PC
= 4.9 Hz), 130.44 (d, J
PC
= 12.8 Hz), 129.95 (d, J
PC
= 8.8 Hz), 125.18 (d, J
PC
= 6.7 Hz),
117.50 (d, J
PC
= 86.0 Hz), 31.17 (d, J
PC
= 48.6 Hz) (two peaks are not resolved).

1
H NMR, 400 MHz, CDCl
3
, 25 °C

Cl
PPh
3
Br
Br
47
13
C NMR, 101 MHz, CDCl
3
, 25 °C

48
1,4-bis[(1Z)-2-(2-bromo-5-chlorophenyl)ethenyl]-2,3-dimethoxybenzene (2.9)

A solution of 2.3 (1.06 g, 5.45 mmol) and 2.6 (6.56 g, 12.0 mmol) in THF (44 ml) was
cooled to 0 °C.
4
Potassium tert-butoxide (1.46 g, 12.4 mmol) dissolved in water (4.4 ml) was
added, dropwise, followed by warming to rt and stirring for 30 min. The resulting mixture was
partitioned between EtOAc and water, and extracted with EtOAc. The combined organic layers
were washed with brine, dried over Na
2
SO
4
, and concentrated under reduced pressure.
Purification by flash column chromatography using 10% EtOAc/hexanes as eluent, followed by
recrystallization from 10% toluene/hexanes afforded a colorless solid (2.10 g, 68%). TLC: 14%
EtOAc/Hexanes, R
f
≈ 0.7. Mp 114-116 °C.
1
H NMR (400 MHz, CDCl
3
) δ 7.47 (d, J = 8.5 Hz,
2H), 7.10 (d, J = 2.6 Hz, 2H), 7.02 (ddd, J = 8.6, 2.6, 0.6 Hz, 2H), 6.82 (d, J = 12.1 Hz, 2H), 6.58
(d, J = 12.0 Hz, 2H), 6.50 (s, 2H), 3.84 (s, 6H).
13
C NMR (101 MHz, CDCl
3
) δ 151.62, 139.51,
133.83, 133.04, 130.35, 130.33, 129.16, 128.78, 127.38, 124.37, 121.73, 61.07.

Br
Br
Cl
Cl
MeO
MeO
49
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

50
8,13-dichloro-3,4-dimethoxydibenzo[c,g]phenanthrene (2.10)

Pd(OAc)
2
(78.7 mg, 0.351 mmol), K
2
CO
3
(0.972 g, 7.03 mmol), Ag
2
CO
3
(0.485 g, 1.76
mmol), PCy
3
·HBF
4
(0.277 g, 0.703 mmol), and 2.9 (2.00 g, 3.51 mmol) were brought up in DMA
(66.8 ml) and allowed to stir at 120 °C for 16 h.
4
Upon completion, the solution was cooled to rt
and filtered through a pad of Celite to remove insoluble salts. The filtrate was concentrated under
reduced pressure and purified by flash column chromatography using 20% DCM/hexanes as
eluent to afford a pale yellow solid (0.900 g, 63%). TLC: 75% DCM/hexanes, R
f
≈ 0.7. Mp 231-
233 °C.
1
H NMR (400 MHz, CDCl
3
) δ 8.31 (d, J = 8.8 Hz, 2H), 8.27 (d, J = 9.2 Hz, 2H), 7.92 (d,
J = 2.1 Hz, 2H), 7.86 (d, J = 8.9 Hz, 2H), 7.21 (dd, J = 9.0, 2.3 Hz, 2H), 4.13 (s, 6H).
13
C NMR
(101 MHz, CDCl
3
) δ 145.32, 133.21, 131.76, 130.39, 128.98, 128.72, 126.97, 126.82, 125.40,
124.15, 121.24, 61.32.

1
H NMR, 400 MHz, CDCl
3
, 25 °C

Cl
Cl
MeO
MeO
51
13
C NMR, 101 MHz, CDCl
3
, 25 °C

52
8,13-dichlorodibenzo[c,g]phenanthrene-3,4-diol (2.11)

A solution of 2.10 (0.603 g, 1.48 mmol) in DCM (16 ml) was cooled to -78 °C for
dropwise addition of 1.0 M BBr
3
in DCM (3.7 ml, 3.70 mmol).
5,6
After 30 min, the reaction was
allowed to warm to rt and stirred for 16 h. The mixture was then cooled to 0 °C and quenched
with water, followed by extraction of the aqueous layer with DCM. The combined organic layers
were washed with brine, dried over Na
2
SO
4
, and concentrated under reduced pressure.
Purification by flash column chromatography using 20% hexanes/DCM as eluent afforded a red
solid (0.320 g, 57%). TLC: 33% hexanes/DCM, R
f
≈ 0.5. Mp > 250 °C.
1
H NMR (400 MHz,
CDCl
3
) δ 8.20 (d, J = 8.4 Hz, 2H), 7.98 – 7.90 (m, 4H), 7.40 – 7.28 (m, 4H).
13
C NMR (101 MHz,
CDCl
3
) δ 182.73, 138.35, 137.16, 135.86, 130.22, 129.57, 128.80, 128.50, 127.67, 127.63,
124.91.

Cl
Cl
HO
HO
53
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

54
HPLC, AD-H column, 100% ACN

55
8,13-dichloro-3,4-bis[(2-ethylhexyl)oxy]dibenzo[c,g]phenanthrene (2.12)

To a solution of 2.11 (0.228g, 0.601 mmol), K
2
CO
3
(0.498 g, 3.61 mmol), and dibenzo-
18-crown-6 (0.0220 g, 0.0601 mmol) in DMF (4 ml), 2-ethylhexyl bromide (0.640 ml, 4.81
mmol) was added.
7
The reaction was heated to 90 °C and allowed to stir for 48 h. The resulting
mixture was cooled to rt and partitioned between DCM and water, followed by extraction of the
aqueous layer with DCM. The combined organic layers were washed with brine, dried over
Na
2
SO
4
, and concentrated under reduced pressure. Purification by flash column chromatography
using 4% DCM/hexanes afforded a yellow oil (0.139 g, 38%). TLC: 9% DCM/hexanes, R
f
≈ 0.5.
1
H NMR (400 MHz, CDCl
3
) δ 8.34 (d, J = 8.9 Hz, 2H), 8.28 (d, J = 9.0 Hz, 2H), 7.92 (d, J = 2.2
Hz, 2H), 7.86 (d, J = 8.8 Hz, 2H), 7.21 (dd, J = 9.0, 2.2 Hz, 2H), 4.31 (m, 2H), 3.98 (m, 2H), 1.92
m, 2H), 1.83 – 1.48 (m, 8H), 1.48 – 1.30 (m, 8H), 1.03 (td, J = 7.5, 2.1 Hz, 6H), 0.95 (dt, J = 6.6,
3.3 Hz, 6H).
13
C NMR (101 MHz, CDCl
3
) δ 144.86, 133.12, 131.60, 130.43, 129.13, 129.03,
126.79, 126.79, 125.32, 124.01, 121.42, 76.97, 40.85, 30.66, 29.31, 24.07, 23.30, 14.28, 11.38.

Cl
Cl
O
O
56
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

57
3,4-bis[(2-ethylhexyl)oxy]-8,13-bis(triisopropylsilylethynyl)dibenzo[c,g]-phenanthrene (2.13)

To a flask containing [PdCl
2
(CH
3
CN)
2
] (13.7 mg, 0.0524 mmol), XPhos (0.153 g, 0.314
mmol), and Cs
2
CO
3
(2.22 g, 6.81 mmol) was added a solution of 2.12 (0.791 g, 1.31 mmol) in
anhydrous 1,4-dioxane (5.2 ml).
8
The suspension was allowed to stir at rt for 25 min prior to the
addition of (triisopropylsilyl)acetylene (1.22 ml, 5.24 mmol). The mixture was heated to 90 °C
and allowed to stir for 16 h. After cooling to rt, the reaction was diluted with water and extracted
with DEE. The combined organic layers were washed with brine, dried over Na
2
SO
4
and
concentrated under reduced pressure. Purification by flash column chromatography using 20%
hexanes/DCM as eluent afforded a yellow oil (0.940g, 80%). TLC: 10% DCM/hexanes, R
f
≈ 0.6.
1
H NMR (400 MHz, CDCl
3
) δ 8.33 (dd, J = 16.5, 8.9 Hz, 4H), 8.14 (d, J = 1.7 Hz, 2H), 7.93 (d, J
= 8.8 Hz, 2H), 7.38 (dd, J = 8.8, 1.7 Hz, 2H), 4.36 (m, 2H), 4.00 (m, 2H), 1.96 (m, 2H), 1.83 –
1.55 (m, 8H), 1.49 – 1.38 (m, 8H), 1.24 (s, 42H), 1.07 (td, J = 7.4, 2.1 Hz, 6H), 0.98 (td, J = 7.0,
2.0 Hz, 6H).
13
C NMR (101 MHz, CDCl
3
) δ 145.04, 131.88, 131.74, 130.36, 129.45, 128.96,
127.81, 127.35, 124.29, 120.91, 120.81, 107.51, 91.35, 76.95, 40.89, 30.68, 29.34, 24.11, 23.34,
18.93, 14.30, 11.60, 11.41.

O
O
TIPS
TIPS
58
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

59
3,4-bis((2-ethylhexyl)oxy)-8,13-diethynyldibenzo[c,g]phenanthrene (2.1)

A solution of 2.13 (0.999 g, 1.12 mmol) in THF (22.3 ml) was cooled to 0 °C.
9
TBAF (1.0
M in THF) was added dropwise and the solution was allowed to warm to rt. After stirring for 16
h, saturated aqueous NaHCO
3
was added to the mixture, which was then extracted with DEE. The
combined organic layers were washed with water, dried over Na
2
SO
4
and concentrated under
reduced pressure. Purification by flash column chromatography using 16% hexanes/DCM as
eluent afforded a yellow oil (0.559 g, 96%). TLC: 25% DCM/hexanes, R
f
≈ 0.7.
1
H NMR (400
MHz, CDCl
3
) δ 8.36 (d, J = 8.8 Hz, 2H), 8.31 (d, J = 8.8 Hz, 2H), 8.14 (d, J = 1.8 Hz, 2H), 7.92
(d, J = 8.7 Hz, 2H), 7.36 (dd, J = 8.8, 1.5 Hz, 2H), 4.39 – 4.28 (m, 2H), 4.06 – 3.95 (m, 2H), 3.20
(s, 2H), 1.99-1.92 (m, 2H), 1.85 – 1.52 (m, 8H), 1.48-1.37 (m, 8H), 1.06 (td, J = 7.5, 2.2 Hz, 6H),
1.01 – 0.93 (m, 6H).
13
C NMR (101 MHz, CDCl
3
) δ 145.09, 132.18, 131.65, 130.55, 129.58,
129.07, 127.59, 127.33, 124.17, 120.94, 119.46, 83.98, 77.89, 76.94, 40.84, 30.65, 29.31, 24.07,
23.30, 14.27, 11.38.

UV-Vis absorption maxima: 258 (ε = 83,300 L mol
-1
cm
-1
), 325 (ε = 48,100 L mol
-1
cm
-1
), and
368 (ε = 8,500 L mol
-1
cm
-1
) nm.

O
O
60
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

61
UV-Vis, 1.42x10
-5
M in CHCl
3

0

0.2

0.4

0.6

0.8

1

1.2

240
290
340
390
440
490

Absorbance

Wavelength
(nm)

62
3,4-bis((2-ethylhexyl)oxy)-8,13-bis(phenylethynyl)dibenzo[c,g]phenanthrene (2.14)

A flask charged with 2.1 (72.5 mg, 0.129 mmol),
tetrakis(triphenylphosphine)palladium(0) (7.4 mg, 6.43 µmol), and copper(I) iodide (1.2 mg, 6.43
µmol) was brought up in THF (1.3 ml).
10
Iodobenzene (43.3 µl, 0.387 mmol) and TEA (0.77 ml)
were then added and the reaction was allowed to stir at 40 °C for 16 h. The reaction mixture was
then cooled to rt and filtered with DCM through a short silica gel column, followed by
concentration of the solvent under reduced pressure. Purification by flash column
chromatography with 8% EtOAc/hexanes as eluent afforded a yellow oil (90.2 mg, 95%) TLC:
17% EtOAc/hexanes, R
f
≈ 0.8.
1
H NMR (400 MHz, CDCl
3
) δ 8.33 (d, J = 8.8 Hz, 4H), 8.15 (d, J
= 1.8 Hz, 2H), 7.92 (d, J = 8.8 Hz, 2H), 7.64 – 7.55 (m, 4H), 7.43 – 7.33 (m, 8H), 4.36 – 4.25 (m,
2H), 4.01 – 3.95 (m, 2H), 1.96 – 1.89 (m, 2H), 1.82 – 1.45 (m, 8H), 1.45 – 1.32 (m, 8H), 1.02 (td,
J = 7.5, 2.1 Hz, 6H), 0.94 (ddt, J = 7.2, 4.9, 1.7 Hz, 6H).
13
C NMR (101 MHz, CDCl
3
) δ 145.06,
131.83, 131.81, 131.34, 130.29, 129.45, 129.12, 128.53, 128.44, 127.39, 124.27, 123.46, 120.87,
120.64, 90.26, 89.83, 76.96, 40.85, 30.66, 29.31, 24.08, 23.31, 14.28, 11.39.

UV-Vis absorption maxima: 283 (ε = 50,900 L mol
-1
cm
-1
), 332 (ε = 49,900 L mol
-1
cm
-1
), and
372 (ε = 17,700 L mol
-1
cm
-1
) nm.

O
O
63

1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

64
Polymerization (2.15)

A mixture of 2.1 (58.9 mg, 0.101 mmol), p-diiodobenzene (33.7 mg, 0.101 mmol),
tetrakis(triphenylphosphine)palladium(0) (5.8 mg, 5.05 µmol), and copper(I) iodide (1.0 mg, 5.05
µmol) were dissolved in THF (10 ml) and TEA (6 ml).
10
The solution was heated to 40 °C and
allowed to stir for 48 h. Phenylacetylene (11 µl, 0.101 mmol) was then added and the solution
continued to stir for 1 h. The reaction was then cooled to rt and filtered through a short silica plug.
The solvent was removed under reduced pressure and the resulting polymer was precipitated in
MeOH. The precipitated polymer was dried under high vacuum for 48 h at 60 °C, resulting in
50.0 mg (75%) of an orange solid. M
n
= 4,411 g/mol, M
w
= 6,531 g/mol, PDI = 1.48.

UV-Vis absorption maxima: 286 (ε = 57,100 L mol
-1
cm
-1
), 348 (ε = 85,100 L mol
-1
cm
-1
), and
382 (ε = 43,300 L mol
-1
cm
-1
) nm.

O
O
n
65
1
H NMR, 400 MHz, CDCl
3
, 25 °C

66
5.3 Chapter 3 Experimental and Spectral Data

6-chloro-1-tetralone (3.4)

A saturated solution of NaNO
2
(3.16 g, 45.7 mmol) in water was added dropwise to a
solution of 6-amino-1-tetralone (6.91 g, 41.6 mmol) in HCl (26.8 ml, 17%) at -10 °C.
11
The
suspension was then transferred to a mixture of copper(I)chloride (57.62 g, 0.582 mol) and HCl
(30.2 ml, 38%) at -10 °C. The mixture was then allowed to warm to rt and stirred for 2 h. Upon
completion, the aqueous solution was extracted with EtOAc and the resulting organic layer was
dried with Na
2
SO
4
. The solvent was removed under reduced pressure and the product was
purified by flash column chromatography using 10% EtOAc/hexanes as eluent, affording a yellow
oil (6.30 g, 84%). TLC: 14% EtOAc/hexanes, R
f
≈ 0.6.
1
H NMR (400 MHz, CDCl
3
) δ 7.87 (dd,
J = 7.9, 3.9 Hz, 1H), 7.24 – 7.09 (m, 2H), 2.88 – 2.85 (m, 2H), 2.76 – 2.45 (m, 2H), 2.10 – 2.03
(m, 2H).
13
C NMR (101 MHz, CDCl
3
) δ 196.98, 145.98, 139.47, 130.97, 128.75, 128.55, 127.02,
38.83, 29.48, 23.03.

Cl
O
67
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

68
1-bromo-6-chloro-3,4-dihydronaphthalene-2-carbaldehyde (3.5)

To a solution of phosphorus tribromide (11.6 ml, 0.123 mol) in DCM (246 ml) at 0 °C,
DMF (10.8 ml, 0.140 mol) was added dropwise.
12
After stirring for 2 h, a solution of 3.4 (8.43 g,
46.7 mmol) in DCM (94 ml) was added at 0 °C. The mixture was allowed to warm to rt and
heated to reflux for 16 h. The reaction was then allowed to cool to rt, followed by addition of a
saturated aqueous solution of NaHCO
3
. The aqueous layer was extracted with DCM. The
combined organic layers were washed with brine, dried over Na
2
SO
4
, and concentrated under
reduced pressure. Purification by flash column chromatography using 4% EtOAc/hexanes as
eluent afforded a yellow solid (8.19 g, 65%). TLC: 14% EtOAc/hexanes, R
f
≈ 0.7. Mp 95-97 °C.
1
H NMR (400 MHz, CDCl
3
) δ 10.22 (s, 2H), 7.81 (d, J = 8.5 Hz, 2H), 7.30 (ddt, J = 8.4, 2.1, 0.6
Hz, 2H), 7.19 (dt, J = 2.0, 1.0 Hz, 2H), 2.81 (dd, J = 9.3, 6.7 Hz, 4H), 2.68 – 2.56 (m, 4H).
13
C
NMR (101 MHz, CDCl
3
) δ 192.94, 140.63, 137.61, 137.36, 134.67, 131.69, 130.14, 127.80,
127.40, 27.19, 22.75.

Cl
Br O
H
69
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

70
1-bromo-6-chloro-2-naphthaldehyde (3.6)

A solution of 3.5 (1.32 g, 4.88 mmol) and DDQ (11.1 g, 48.8 mmol) in toluene (30 ml)
was allowed to stir at reflux for 16 h.
12
The reaction mixture was then cooled to rt and filtered
through Celite. The solvent was evaporated under reduced pressure, and the resulting residue was
purified by flash chromatography using 50% toluene/hexanes as eluent to afford a white solid
(0.689 g, 52%). TLC: 50% toluene/hexanes, R
f
≈ 0.5. Mp 115.5-117.5 °C.
1
H NMR (400 MHz,
CDCl
3
) δ 10.63 (s, 1H), 8.44 (d, J = 9.1 Hz, 1H), 7.95 (d, J = 8.5 Hz, 1H), 7.86 (d, J = 2.1 Hz,
1H), 7.76 (d, J = 8.5 Hz, 1H), 7.62 (dd, J = 9.1, 2.1 Hz, 1H).
13
C NMR (101 MHz, CDCl
3
) δ
192.47, 137.78, 136.20, 131.58, 130.96, 130.63, 129.96, 129.26, 127.49, 127.29, 125.49.

1
H NMR, 400 MHz, CDCl
3
, 25 °C

Cl
Br O
H
71
13
C NMR, 101 MHz, CDCl
3
, 25 °C

72
1-bromo-6-chloro-2-methylnaphthalene (3.1)

KOH (0.385 g, 6.87 mmol) was added to a solution of 3.6 (0.618 g, 2.29 mmol) in DEG
(23 ml).
12
The reaction was then cooled to 0 °C for the addition of hydrazine monohydrate (0.30
ml, 5.96 mmol). The reaction was allowed to warm to rt and heated to 180 °C to stir for 2 h. After
cooling to rt, water was added to the mixture, followed by the addition of 4 M HCl until the
reaction was neutralized. The aqueous layer was extracted with DEE. The combined organic
layers were washed with brine, dried over Na
2
SO
4
, and concentrated under reduced pressure.
Purification by flash column chromatography using 2% EtOAc/hexanes afforded a white solid
(0.490 g, 84%). TLC: 100% hexanes, R
f
≈ 0.7. Mp 61-63 °C.
1
H NMR (400 MHz, CDCl
3
) δ 8.21
(d, J = 9.1 Hz, 1H), 7.75 (d, J = 2.3 Hz, 1H), 7.58 (d, J = 8.5 Hz, 1H), 7.47 (dd, J = 9.1, 2.2 Hz,
1H), 7.34 (d, J = 8.4 Hz, 1H), 2.60 (s, 3H).
13
C NMR (101 MHz, CDCl
3
) δ 136.51, 133.57,
131.79, 130.98, 129.91, 128.90, 128.09, 126.64, 126.43, 124.03, 77.48, 77.16, 76.84, 24.24.

Cl
Br
73
1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

74
1-bromo-2-(bromomethyl)-6-chloronaphthalene (3.8)

A solution of 3.1 (2.12 g, 8.35 mmol), NBS (1.34 g, 7.51 mmol), and BPO (0.203 g, 0.835
mmol) in CCl
4
(25 ml) was allowed to stir at reflux for 16 h.
13
The reaction mixture was cooled to
rt, filtered to remove the solid succinimide, and the filtrate was concentrated under reduced
pressure. Purification by flash column chromatography with 100% hexanes as eluent afforded a
white solid (2.00 g, 80%) TLC: 100% hexanes, R
f
≈ 0.4. Mp 97-99 °C.
1
H NMR (400 MHz,
CDCl
3
) δ 8.26 (d, J = 9.1 Hz, 1H), 7.79 (d, J = 2.1 Hz, 1H), 7.69 (d, J = 8.5 Hz, 1H), 7.53 (d, J =
7.9 Hz, 2H), 4.83 (s, 2H).
13
C NMR (101 MHz, CDCl
3
) δ 135.47, 134.72, 133.55, 131.03, 129.68,
128.94, 128.79, 127.50, 126.87, 124.94, 77.48, 77.16, 76.84, 34.50.

1
H NMR, 400 MHz, CDCl
3
, 25 °C

Cl
Br
Br
75
13
C NMR, 101 MHz, CDCl
3
, 25 °C

76
[(1-bromo-6-chloro-2-naphthalenyl)methyl]triphenylphosphonium bromide (3.9)

A solution of 3.8 (1.83 g, 5.48 mmol) and triphenylphosphine (1.44 g, 5.48 mmol) in
DMF (6 ml) was stirred at reflux for 3 h.
2
The mixture was allowed to cool to rt and filtered to
collect the product, which was subsequently washed with cold toluene, followed by cold hexanes.
The product was obtained as a colorless solid (3.18 g, 97%). Mp > 250 °C.
1
H NMR (400 MHz,
CDCl
3
) δ 7.80 (d, J = 9.1 Hz, 1H), 7.75 – 7.46 (m, 18H), 7.37 (dd, J = 9.1, 2.1 Hz, 1H), 5.75 (d, J
= 14.4 Hz, 2H).
13
C NMR (101 MHz, CDCl
3
) δ 135.27 (d, J
PC
= 3.1 Hz), 134.24 (d, J
PC
= 9.9 Hz),
133.43 (d, J
PC
= 2.2 Hz), 130.23 (d, J
PC
= 12.7 Hz), 129.80 (d, J
PC
= 3.8 Hz), 129.12 (d, J
PC
= 1.6
Hz), 128.82 (d, J
PC
= 1.5 Hz), 127.89 (d, J
PC
= 9.1 Hz), 127.58 (d, J
PC
= 3.0 Hz), 126.81 (d, J
PC
=
2.0 Hz), 126.41 (d, J
PC
= 9.2 Hz), 117.11 (d, J
PC
= 85.7 Hz), 32.44 (d, J
PC
= 47.9 Hz) (two peaks
are not resolved).

1
H NMR, 400 MHz, CDCl
3
, 25 °C

Cl
Br
PPh
3
Br
77
13
C NMR, 101 MHz, CDCl
3
, 25 °C

78
1-bromo-2-((Z)-4-((Z)-2-bromo-5-chlorostyryl)-2,3-dimethoxystyryl)-6-chloro-naphthalene (3.10)

A solution of 2.3 (1.28 g, 6.60 mmol) and 2.6 (3.28 g, 6.00 mmol) in THF (48 ml) was
cooled to 0 °C. Potassium tert-butoxide (0.780 g, 6.60 mmol) dissolved in water (5 ml) was
added, dropwise, followed by warming to rt and stirring for 30 min. The resulting mixture was
partitioned between EtOAc and water, and extracted with EtOAc. The combined organic layers
were washed with brine, dried over Na
2
SO
4
, and concentrated under reduced pressure.
Purification by flash column chromatography using 15% EtOAc/hexanes as eluent isolated the
isomeric mixture of the desired aldehyde, which was carried on without any additional
purification. To this aldehyde was added 3.9 (3.00 g, 5.03 mmol) and 40 ml of THF. A solution of
potassium tert-butoxide (0.653 g, 5.50 mmol) in water (4 ml) was added dropwise, followed by
warming to rt and stirring for 30 min. The resulting mixture was partitioned between EtOAc and
water, and extracted with EtOAc. The combined organic layers were washed with brine, dried
over Na
2
SO
4
, and concentrated under reduced pressure. Purification by flash column
chromatography with 40% toluene/hexanes as eluent afforded a pale yellow oil (1.99 g, 64%).
TLC: 50% toluene/hexanes, R
f
≈ 0.5.
1
H NMR (400 MHz, CDCl
3
) δ 8.25 (d, J = 9.1 Hz, 1H),
7.71 (d, J = 1.9 Hz, 1H), 7.50 – 7.40 (m, 3H), 7.20 (d, J = 8.5 Hz, 1H), 7.07 (d, J = 2.6 Hz, 1H),
6.99 (ddt, J = 8.5, 2.5, 0.6 Hz, 1H), 6.95 – 6.86 (m, 2H), 6.82 (d, J = 12.1 Hz, 1H), 6.58 (d, J =
12.0 Hz, 1H), 6.48 – 6.35 (m, 2H), 3.89 (d, J = 10.4 Hz, 6H).
13
C NMR (101 MHz, CDCl
3
) δ
151.63, 151.47, 139.43, 136.41, 134.22, 133.83, 132.78, 132.73, 131.10, 131.01, 130.87, 130.34,
MeO
MeO
Br
Cl
Br
Cl
79
130.21, 129.25, 129.20, 129.10, 128.71, 128.16, 127.48, 126.76, 126.72, 126.26, 125.12, 124.31,
123.82, 121.85, 61.10, 61.09.

1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

80

3,14-dichloro-7,8-dimethoxyhexahelicene (3.11)

Pd(OAc)
2
(29.1 mg, 0.130 mmol), K
2
CO
3
(0.359 g, 2.60 mmol), Ag
2
CO
3
(0.179 g, 0.650
mmol), PCy
3
·HBF
4
(0.102g, 0.260 mmol), and 3.10 (0.400 g, 0.650 mmol) were brought up in
DMA (6.5 ml) and stirred at 120 °C for 16 h. Upon completion, the solution was cooled to rt and
filtered through a pad of Celite to remove insoluble salts. The filtrate was concentrated under
reduced pressure and purified by flash column chromatography using 20% DCM/hexanes as
eluent to afford a yellow semi-solid (31.7 mg, 11%). TLC: 66% hexanes/DCM, R
f
≈ 0.6.
1
H
NMR (400 MHz, CDCl
3
) δ 8.40 (dd, J = 8.4, 0.6 Hz, 1H), 8.37 (d, J = 8.8 Hz, 1H), 7.99 (d, J =
8.4 Hz, 1H), 7.96 (d, J = 8.6 Hz, 1H), 7.86 (d, J = 8.8 Hz, 1H), 7.83 – 7.76 (m, 3H), 7.44 (dd, J =
14.4, 9.1 Hz, 2H), 6.66 (dt, J = 9.1, 2.6 Hz, 2H), 4.22 (s, 3H), 4.17 (s, 3H).
13
C NMR (101 MHz,
CDCl
3
) δ 145.20, 144.98, 133.06, 132.40, 131.50, 131.23, 130.81, 130.02, 129.39, 129.27,
128.22, 128.12, 127.79, 127.76, 127.63, 127.58, 127.27, 126.84, 126.65, 126.65, 125.63, 125.44,
125.34, 121.53, 121.21, 120.89, 61.43, 61.40.

MeO
MeO
Cl
Cl
81

1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

82

3,14-dichlorohexahelicene-7,8-diol (3.12)

A solution of 3.11 (31.7 mg, 0.0695 mmol) in DCM (1.4 ml) was cooled to -78 °C for
dropwise addition of BBr
3
1.0 M in DCM (0.174 ml, 0.174 mmol). After 30 min, the reaction was
allowed to warm to rt and stir for 5 h. The mixture was then quenched with water, followed by
extraction of the aqueous layer with DCM. The combined organic layers were washed with brine,
dried over Na
2
SO
4
, and concentrated under reduced pressure. Purification by flash column
chromatography using 100% DCM as eluent afforded a red solid (19.4 mg, 65%). TLC: 100%
DCM, R
f
≈ 0.6.
1
H NMR (400 MHz, CDCl
3
) δ 8.30 (d, J = 8.0 Hz, 2H), 8.19 (d, J = 8.4 Hz, 2H),
7.98 (d, J = 7.9 Hz, 2H), 7.86 (d, J = 8.4 Hz, 2H), 7.81 (s, 4H), 7.77 (dd, J = 9.1, 2.2 Hz, 4H),
7.06 (d, J = 9.0 Hz, 2H), 6.86 (dd, J = 9.2, 0.7 Hz, 2H), 6.78 (dd, J = 9.2, 2.2 Hz, 2H), 6.69 (dd, J
= 9.0, 2.3 Hz, 2H).
13
C NMR (101 MHz, CDCl
3
) δ 183.46, 181.99, 140.39, 137.98, 137.58,
135.47, 135.32, 133.88, 133.39, 130.33, 130.28, 130.21, 129.96, 129.71, 129.48, 128.90, 128.30,
127.80, 127.80, 127.66, 127.51, 127.43, 127.10, 125.78, 125.62, 124.83.

HO
HO
Cl
Cl
83

1
H NMR, 400 MHz, CDCl
3
, 25 °C

13
C NMR, 101 MHz, CDCl
3
, 25 °C

84
5.4 References
(1) John Plater, M. J. Chem. Soc. Perkin 1 1997, 2903.
(2) Caruso, A.; Siegler, M. A.; Tovar, J. D. Angew. Chem. Int. Ed. 2010, 49, 4213.
(3) Kuhnert, N.; Rossignolo, G. M.; Lopez-Periago, A. Org. Biomol. Chem. 2003, 1, 1157.
(4) Kamikawa, K.; Takemoto, I.; Takemoto, S.; Matsuzaka, H. J. Org. Chem. 2007, 72, 7406.
(5) Nakajima, M.; Miyoshi, I.; Kanayama, K.; Hashimoto, S.-I. J. Org. Chem. 1999, 64, 2264.
(6) Bandind, M.; Casolari, S.; Cozzi, P. G.; Proni, G.; Schmohel, E.; Spada, G. P.; Tagliavini,
E.; Umani-Ronchi, A. Eur. J. Org. Chem. 2000, 2000, 491.
(7) Howard, M. J.; Heirtzler, F. R.; Dias, S. I. G. J. Org. Chem. 2008, 73, 2548.
(8) Gelman, D.; Buchwald, S. L. Angew. Chem. Int. Ed.. 2003, 42, 5993.
(9) Wipf, P.; Graham, T. H. J. Am. Chem. Soc. 2004, 126, 15346.
(10) Yuan, W. Z.; Hu, R.; Lam, J. W. Y.; Xie, N.; Jim, C. K. W.; Tang, B. Z. Chem-Eur J. 2012,
18, 2847.
(11) Cui, L.-Q.; Dong, Z.-L.; Liu, K.; Zhang, C. Org. Lett. 2011, 13, 6488.
(12) Furukawa, A.; Arita, T.; Fukuzaki, T.; Mori, M.; Honda, T.; Satoh, S.; Matsui, Y.;
Wakabayashi, K.; Hayashi, S.; Nakamura, K.; Araki, K.; Kuroha, M.; Tanaka, J.; Wakimoto,
S.; Suzuki, O.; Ohsumi, J. Eur. J. Med. Chem. 2012, 54, 522.
(13) Imoto, M.; Ikeda, H.; Fujii, T.; Taniguchi, H.; Tamaki, A.; Takeda, M.; Mizuno, K. Org.
Lett. 2010, 12, 1940.

85
Bibliography
Aloui, F., Abed, R. E., Marinetti, A., & Hassine, B. B. (2008). Synthesis and resolution of a new
helically chiral azahelicene. Tetrahedron Letters, 49(26), 4092–4095.

Aloui, F., El Abed, R., Marinetti, A., & Ben Hassine, B. (2009). A new approach to 3,14-
dihydroxyhexahelicene: Resolution and attribution of the absolute configuration. Comptes Rendus
Chimie, 12(1–2), 284–290.

Balaban, A. T. (2003). Theoretical Examination of New Forms of Carbon Formed by Intra- or
Intermolecular Dehydrogenation of Polycyclic Aromatic Hydrocarbons, Particularly Helicenes.
Polycyclic Aromatic Compounds, 23(3), 277–296.

Bandind, M., Casolari, S., Cozzi, P. G., Proni, G., Schmohel, E., Spada, G. P., … Umani-Ronchi,
A. (2000). Synthesis and Characterization of New Enantiopure 7,7’-Disubstituted 2,2'-Dihydroxy-
1,1'-binaphthyls: Useful Ligands for Asymmetric Allylation Reaction of Aldehydes. European
Journal of Organic Chemistry, 2000(3), 491–497.

Bendikov, M., Wudl, F., & Perepichka, D. F. (2004). Tetrathiafulvalenes, oligoacenenes, and
their buckminsterfullerene derivatives: the brick and mortar of organic electronics. Chemical
Reviews, 104(11), 4891–4946.

Berthod, M., Mignani, G., Woodward, G., & Lemaire, M. (2005). Modified BINAP: the how and
the why. Chemical Reviews, 105(5), 1801–1836.

Bundgaard, E., & Krebs, F. C. (2007). Low band gap polymers for organic photovoltaics. Solar
Energy Materials & Solar Cells, 91(11), 954–985.

Bédard, A.-C., Vlassova, A., Hernandez-Perez, A. C., Bessette, A., Hanan, G. S., Heuft, M. A., &
Collins, S. K. (2013). Synthesis, Crystal Structure and Photophysical Properties of Pyrene–
Helicene Hybrids. Chemistry – A European Journal, 19(48), 16295–16302.

Bürgi, T., Urakawa, A., Behzadi, B., Ernst, K.-H., & Baiker, A. (2004). The absolute
configuration of heptahelicene: a VCD spectroscopy study. New Journal of Chemistry, 28(3),
332–334.

Caruso, A., Siegler, M. A., & Tovar, J. D. (2010). Synthesis of Functionalizable Boron-
Containing π-Electron Materials that Incorporate Formally Aromatic Fused Borepin Rings.
Angewandte Chemie, International Edition, 49(25), 4213–4217.

Cheng, H., & Pu, L. (1999). Synthesis of chiral conjugated propeller‐like polymers using optically
active 1, 1′‐binaphthyl‐2, 2′‐diamine derivatives. Macromolecular Chemistry and Physics.

Cheng, Y., Song, J., Zou, X., Zhang, S., Liu, Y., & Huang, H. (2006). Polybinaphthyls
incorporating chiral 2,2′-binaphthyl and isoquinoline moieties by Sonogashira reaction. Polymer,
47(19), 6598–6605.
86
Cho, M. J., Choi, D. H., Sullivan, P. A., Akelaitis, A. J. P., & Dalton, L. R. (2008). Recent
progress in second-order nonlinear optical polymers and dendrimers. Progress in Polymer
Science, 33(11), 1013–1058.

Collins, S. K., Grandbois, A., Vachon, M. P., & Côté, J. (2006). Preparation of helicenes through
olefin metathesis. Angewandte Chemie International Edition, 45(18), 2923–2926.

Crowther, G. P., Sundberg, R. J., & Sarpeshkar, A. M. (1984). Dilithiation of aromatic ethers. The
Journal of Organic Chemistry, 49(24), 4657–4663.

Cui, L.-Q., Dong, Z.-L., Liu, K., & Zhang, C. (2011). Design, synthesis, structure, and
dehydrogenation reactivity of a water-soluble o-iodoxybenzoic acid derivative bearing a
trimethylammonium group. Organic Letters, 13(24), 6488–6491.

Dai, Y., Katz, T. J., & Nichols, D. A. (1996). Synthesis of a Helical Conjugated Ladder Polymer.
Angewandte Chemie International Edition, 35, 2109–2111.

Dalton, L. (2002). Nonlinear Optical Polymeric Materials: From Chromophore Design to
Commercial Applications. In Polymers for Photonics Applications I (pp. 1–86). Springer Berlin
Heidelberg.

Dunne, E. C. (2002). Co-operative ortho -effects on the Wittig reaction. Interpretation of
stereoselectivity in the reaction of ortho -halo-substituted benzaldehydes and
benzylidenetriphenylphosphoranes. Tetrahedron Letters, 43, 2449–2453.

Flammand-Barbieux, M., Nasielski, J., & Martin, R. H. (1967). Synthesis of Heptahelicene (1)
Benzo[c]phenanthro[4,3-g]phenanthrene. Tetrahedron Letters, 8(8), 743–744.

Fox, J. M., Lin, D., Itagaki, Y., & Fujita, T. (1998). Synthesis of Conjugated Helical Acetylene-
Bridged Polymers and Cyclophanes. The Journal of Organic Chemistry, 63(6), 2031–2038.

Furukawa, A., Arita, T., Fukuzaki, T., Mori, M., Honda, T., Satoh, S., … Ohsumi, J. (2012).
Synthesis and biological evaluation of novel (−)-cercosporamide derivatives as potent selective
PPARγ modulators. European Journal of Medicinal Chemistry, 54, 522–533.

Gelman, D., & Buchwald, S. L. (2003). Efficient palladium-catalyzed coupling of aryl chlorides
and tosylates with terminal alkynes: use of a copper cocatalyst inhibits the reaction. Angewandte
Chemie International Edition , 42(48), 5993–5996.

Gingras, M. (2013a). One hundred years of helicene chemistry. Part 1: non-stereoselective
syntheses of carbohelicenes. Chemical Society Reviews, 42(3), 968–1006.

Gingras, M. (2013b). One hundred years of helicene chemistry. Part 3: applications and properties
of carbohelicenes. Chemical Society Reviews, 42(3), 1051–1095.

Gingras, M., Félix, G., & Peresutti, R. (2013). One hundred years of helicene chemistry. Part 2:
stereoselective syntheses and chiral separations of carbohelicenes. Chemical Society Reviews,
42(3), 1007–1050.
87
Görl, C., Beck, N., Kleiber, K., & Alt, H. G. (2012). Iron(III) complexes with meta-substituted
bis(arylimino)pyridine ligands: Catalyst precursors for the selective oligomerization of ethylene.
Journal of Molecular Catalysis. A, Chemical, 352(0), 110–127.

Günes, S., Neugebauer, H., & Sariciftci, N. S. (2007). Conjugated Polymer-Based Organic Solar
Cells. Chemical Reviews, 107(4), 1324–1338.

Hatakeyama, T., Hashimoto, S., Oba, T., & Nakamura, M. (2012). Azaboradibenzo[6]helicene:
carrier inversion induced by helical homochirality. Journal of the American Chemical Society,
134(48), 19600–19603.

Hoeben, F. J. M., Jonkheijm, P., Meijer, E. W., & Schenning, A. P. H. J. (2005). About
Supramolecular Assemblies of π-Conjugated Systems. Chemical Reviews, 105(4), 1491–1546.

Howard, M. J., Heirtzler, F. R., & Dias, S. I. G. (2008). Synthesis and stereochemistry of long-
chain quinoxaline metallocyclophanes. The Journal of Organic Chemistry, 73(7), 2548–2553.

Imoto, M., Ikeda, H., Fujii, T., Taniguchi, H., Tamaki, A., Takeda, M., & Mizuno, K. (2010).
Contrasting intermolecular and intramolecular exciplex formation of a 1,4-dicyano-2-
methylnaphthalene-N,N-dimethyl-p-toluidine dyad. Organic Letters, 12(9), 1940–1943.

Janke, R. H., Haufe, G., Wurthwein, E.-U., & Borkent, J. H. (1996). Racemization Barriers of
Helicenes: A Computational Study1. Journal of the American Chemical Society, 118, 6031–6035.

John Plater, M. (1997). Fullerene tectonics. Part 2.1 Synthesis and pyrolysis of halogenated
benzo[c]phenanthrenes. Journal of the Chemical Society. Perkin Transactions 1, (19), 2903–
2909.

Kajzar, F., & Chollet, P.-A. (1997). Poled Polymers and their Applications to SHG and EO
Devices. (S. Miyata & H. Sasabe, Eds.) (Vol. 4). Gordon and Breach Science Publishers.

Kamikawa, K., Takemoto, I., Takemoto, S., & Matsuzaka, H. (2007). Synthesis of helicenes
utilizing palladium-catalyzed double C-H arylation reaction. The Journal of Organic Chemistry,
72(19), 7406–7408.

Kauranen, M., Verbiest, T., Boutton, C., Teerenstra, M. N., Clays, K., Schouten, A. j, …
Persoons, A. (1995). Supramolecular Second-Order Nonlinearity of Polymers with
Orientationally Correlated Chromophores. Science, 270, 966–969.

Kim, T.-D., Kang, J.-W., Luo, J., Jang, S.-H., Ka, J.-W., Tucker, N., … Jen, A. K.-Y. (2007).
Ultralarge and thermally stable electro-optic activities from supramolecular self-assembled
molecular glasses. Journal of the American Chemical Society, 129(3), 488–489.

Kokado, K., Tokoro, Y., & Chujo, Y. (2009). Luminescent and Axially Chiral π-Conjugated
Polymers Linked by Carboranes in the Main Chain. Macromolecules, 42(23), 9238–9242.
Kondo, K., Okuda, M., & Fujitani, T. (1993). Synthesis and Nonlinear Optics of Soluble
Poly(phenyleneethynylene). Macromolecules, 26, 7382.

88
Kuhnert, N., Rossignolo, G. M., & Lopez-Periago, A. (2003). The synthesis of trianglimines: on
the scope and limitations of the [3 + 3] cyclocondensation reaction between (1R,2R)-
diaminocyclohexane and aromatic dicarboxaldehydes. Organic & Biomolecular Chemistry, 1(7),
1157–1170.

Lehnherr, D., & Tykwinski, R. R. (2011). Conjugated Oligomers and Polymers Based on
Anthracene, Tetracene, Pentacene, Naphthodithiophene, and Anthradithiophene Building Blocks.
Australian Journal of Chemistry, 64(7), 919–929.

Ma, L., Hu, Q.-S., Musick, K. Y., Vitharana, D., Wu, C., & Pu, L. (1996). Conjugated Polymers
with Main Chain Chirality. 3. Synthesis of Optically Active Poly(aryleneethynylene)s.
Macromolecules, 29, 5083–5090.

Martin, R. H., & Baes, M. (1975). Helicenes : Photosyntheses of [11], [12] and [14]helicene.
Tetrahedron, 31(17), 2135–2137.

Martin, R. H., & Marchant, M. J. (1974). Thermal Racemisation of Hepta-, Octa-, and
Nonahelicene. Tetrahedron, 30, 347–349.

Martin, R. H., & Marchant, M.-J. (1972). Thermal Racemisation of [6], [7], [8] and [9]Helicene.
Tetrahedron Letters, 35, 3707–3708.

Mikeš, F., Boshart, G., & Gil-Av, E. (1976a). Helicenes. Resolution on chiral charge-transfer
complexing agents using high performance liquid chromatography. Journal of the Chemical
Society. Chemical Communications, (3).

Mikeš, F., Boshart, G., & Gil-Av, E. (1976b). Resolution of Optical Isomers by High-
Performance Liquid Chromatography, Using Coated and Bonded Chiral Charge-Transfer
Complexing Agents as Stationary Phases. Journal of Chromatography, 122, 205–221.

Minuti, L., Taticchi, A., Marrocchi, A., Gacs-Baitz, E., & Galeazzi, R. (1999). An Efficient
Synthetic Approach to Substituted Penta- and Hexahelicenes. European Journal of Organic
Chemistry, 1999(11), 3155–3163.

Nakajima, M., Miyoshi, I., Kanayama, K., & Hashimoto, S.-I. (1999). Enantioselective Synthesis
of Binaphthol Derivatives by Oxidative Coupling of Naphthol Derivatives Catalyzed by Chiral
Diamine‚Copper Complexes. The Journal of Organic Chemistry, 64, 2264–2271.

Newman, M. S., & Lednicer, D. (1956). The Synthesis and Resolution of Hexahelicene. Journal
of the American Chemical Society, 78(18), 4765–4770.

Oda, M., Meskers, S., Nothofer, H., Scherf, U., & Neher, D. (2000). Chiroptical properties of
chiral-substituted polyfluorenes. Synthetic Metals, 111–112(0), 575–577.

Padmanaban, G., & Ramakrishnan, S. (2000). Conjugation Length Control in Soluble Poly[2-
methoxy-5-((2‘-ethylhexyl)oxy)-1,4-phenylenevinylene] (MEHPPV): Synthesis, Optical
Properties, and Energy Transfer. Journal of the American Chemical Society, 122(10), 2244–2251.

89
Pu, L. (1998). 1,1‘-Binaphthyl Dimers, Oligomers, and Polymers: Molecular Recognition,
Asymmetric Catalysis, and New Materials. Chemical Reviews, 98(7), 2405–2494.

Pu, L. (2000). Novel chiral conjugated macromolecules for potential electrical and optical
applications. Macromolecular Rapid Communications, 21(12), 795–809.

Rajca, A., & Miyasaka, M. (2007). Synthesis and Characterization of Novel Chiral Conjugated
Materials. In T. J. J. Müller & U. H. F. Bunz (Eds.), Functional Organic Materials. Syntheses,
Strategies, and Applications (pp. 547–581). Wiley-VCH.

Roy, A. H., & Hartwig, J. F. (2001). Reductive elimination of aryl halides from palladium(II).
Journal of the American Chemical Society, 123(6), 1232–1233.

Sahasithiwat, S., Mophuang, T., Menbangpung, L., Kamtonwong, S., & Sooksimuang, T. (2010).
3,12-Dimethoxy-7,8-dicyano-[5]helicene as a novel emissive material for organic light-emitting
diode. Synthetic Metals, 160, 1148–1152.

Sapountzis, I., Dube, H., Lewis, R., Gommermann, N., & Knochel, P. (2005). Synthesis of
functionalized nitroarylmagnesium halides via an iodine-magnesium exchange. The Journal of
Organic Chemistry, 70(7), 2445–2454.

Satrijo, A., Meskers, S. C. J., & Swager, T. M. (2006). Probing a conjugated polymer’s transfer of
organization-dependent properties from solutions to films. Journal of the American Chemical
Society, 128(28), 9030–9031.

Shen, Y., & Chen, C.-F. (2012). Helicenes: synthesis and applications. Chemical Reviews, 112(3),
1463–1535.

Shi, L., Liu, Z., Dong, G., Duan, L., Qiu, Y., Jia, J., … Tao, X. (2012). Synthesis, structure,
properties, and application of a carbazole-based diaza[7]helicene in a deep-blue-emitting OLED.
Chemistry – a European Journal, 18(26), 8092–8099.

Shockravi, A., Javadi, A., & Abouzari-Lotf, E. (2013). Binaphthyl-based macromolecules: a
review. RSC Advances, 3(19), 6717.

Stammel, C., Fröhlich, R., Wolff, C., Wenck, H., de Meijere, A., & Mattay, J. (1999). Synthesis
and X-ray Analysis of New [5]Helicenes – HMO Calculations on the Photocyclization of the
Stilbene Precursors. European Journal of Organic Chemistry, 1999(7), 1709–1718.

Suda, K., & Akagi, K. (2011). Self-Assembled Helical Conjugated Poly(m-phenylene)
Derivatives That Afford Whiskers with Hexagonal Columnar Packed Structure. Macromolecules,
44(24), 9473–9488.

Takahira, Y., Sugiura, H., & Yamaguchi, M. (2006). Synthesis and ring size effect of macrocyclic
ethynylhelicene oligomers. The Journal of Organic Chemistry, 71(2), 763–767.

Teplý, F., Stará, I. G., Starý, I., Kollárovič, A., Šaman, D., Rulíšek, L., & Fiedler, P. (2002).
Synthesis of [5]-, [6]-, and [7]Helicene via Ni(0)- or Co(I)-Catalyzed Isomerization of Aromatic
cis , cis -Dienetriynes. Journal of the American Chemical Society, 124(31), 9175–9180.
90

Turner, E. H. (1966). High-Frequency Electro-Optic Coefficients of Lithium Niobate. Applied
Physics Letters, 8(11), 303–304.

Verbiest, T., Elshocht, S. V., Kauranen, M., Hellemans, L., Snauwaert, J., Nuckolls, C., …
Persoons, A. (1998). Strong enhancement of nonlinear optical properties through supramolecular
chirality. Science, 282(5390), 913–915.

Wang, Z. Y., Qi, Y., Bender, T. P., & Gao, J. P. (1997). Condensation Polyimides from AB-Type
Amino Anhydride Monomers. Macromolecules, 30(4), 764–769.

Watanabe, K., Suda, K., & Akagi, K. (2013). Hierarchically self-assembled helical aromatic
conjugated polymers. Journal of Materials Chemistry, 1(16), 2797.

Weitzenböck, H., & Lieb, R. (1912). Eine neue Synthese des Chrysens. Monatshefte Für Chemie
Und Verwandte Teile Anderer Wissenschaften, 33(5), 549–565.

Weitzenböck, R., & Klingler, A. (1918). Synthese der isomeren Kohlenwasserstoffe 1, 2–5, 6-
Dibenzanthracen und 3, 4–5, 6-Dibenzphenanthren. Monatshefte Für Chemie, 39(5), 315–323.

Wipf, P., & Graham, T. H. (2004). Total synthesis of (-)-disorazole C1. Journal of the American
Chemical Society, 126(47), 15346–15347.

Yamamoto, J., Shibata, T., & Soai, K. (2001). Asymmetric Induction by Helical Hydrocarbons:
[6]- and [5]Helicenes. Angewandte Chemie International Edition, 40(6), 1096–1098.

Yang, Y, Da, R., & Smilgies, D. (2013). Induction of Circularly Polarized Electroluminescence
from an Achiral Light‐Emitting Polymer via a Chiral Small‐Molecule Dopant. Advanced
Materials.

Yang, Ying, da Costa, R. C., Fuchter, M. J., & Campbell, A. J. (2013). Circularly polarized light
detection by a chiral organic semiconductor transistor. Nature Photonics, 7(8), 634–638.

Yuan, W. Z., Hu, R., Lam, J. W. Y., Xie, N., Jim, C. K. W., & Tang, B. Z. (2012). Conjugated
hyperbranched poly(aryleneethynylene)s: synthesis, photophysical properties, superquenching by
explosive, photopatternability, and tunable high refractive indices. Chemistry – a European
Journal 18(10), 2847–2856.

Zhao, X., & Schanze, K. S. (2006). Meta-linked poly(phenylene ethynylene) conjugated
polyelectrolyte featuring a chiral side group: helical folding and guest binding. Langmuir: The
ACS Journal of Surfaces and Colloids, 22(10), 4856–4862.

Zimcik, P., Miletin, M., Radilova, H., Novakova, V., Kopecky, K., Svec, J., & Rudolf, E. (2009).
Synthesis, properties and in vitro photodynamic activity of water-soluble azaphthalocyanines and
azanaphthalocyanines. Photochemistry and Photobiology, 86(1), 168–175.

Abstract (if available)

Abstract The synthetic route toward a helicene monomer and its subsequent copolymerization with an aryl connector are presented. The introduction (Chapter 1) provides an overview of the significance of chiral conjugated polymers. Following this, helicene and its properties are discussed in the context of presenting it as a desirable component of these polymers. ❧ Chapter 2 begins with a discussion of the desirable features of a helicene-based polymer and continues with a description of the synthetic strategies that may be utilized to incorporate desired functionalities. The route toward the helicene monomer is centered around a palladium- catalyzed double C-H arylation reaction. The remaining reactions focus on either the preparation of the precursor to this key transformation, or the subsequent functionalization that readies this helicene for polymerization. The copolymerization of the functionalized helicene with an aryl connector is described, along with the resulting absorption spectra, which provide evidence of the desired extended conjugation between the monomer units. ❧ Chapter 3 presents the progress made on a synthetic route toward a longer, more conformationally stable helicene monomer. The C-H arylation is still utilized, but a modified substrate for that reaction is required. Chapter 4 extends the theme of preparing a more stable helicene, with the description of additional synthetic strategies toward this goal. Together, this chemistry opens up helicenes as tunable components for use in new chiral conjugated polymers.

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Creator Olsen, Janet Marie (author)

Core Title Design and synthesis of helicene-based macromolecules

School College of Letters, Arts and Sciences

Degree Doctor of Philosophy

Degree Program Chemistry

Publication Date 09/02/2014

Defense Date 08/07/2014

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Advisor Hogen-Esch, Thieo E. (committee chair), Prakash, G. K. Surya (committee member), Shing, Katherine (committee member)

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