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99
chemical shifts were determined relative to internal tetramethylsilane at 0.0 ppm
or to the 13C signal of CDCl3 at 77.0 ppm. The 19F NMR chemical shifts were
determined relative to CFCl3 at 0.0 ppm as internal standard. Column
chromatography was carried out using Sorbent 60, 65-250 mesh silica gel. TLC
was performed on plastic backed silica plates (60F254, 0.2 mm) which were
visualized using UV fluorescence and Iodine.
3.4.1 General Procedure
1,2-Phenylenediamine (216 mg, 2 mmol) was transferred to a 15 mL
pressure tube equipped with a magnetic stirrer. To this was added NafionÒ-H
powder (0.625g). The fluorinated ketone (2 mmol) was measured out separately in
a 4 mL vial, dissolved in dichloromethane (3 mL) and the solution was transferred
to the pressure tube. The tube was then closed and placed in a preheated oil bath
(120 °C) with proper stirring. The progress of the reaction was monitored by 19F
NMR and reaction was continued till the complete conversion of the fluoroketone.
The reaction mixture was filtered and the catalyst was washed with
dichloromethane successively and kept for recycling. The solvent was removed
from the filtrate under reduced pressure to obtain the pure products, which were
characterized by comparing their spectral data with those of the authentic samples.
Object Description
| Title | Synthesis of organofluorine compounds via Lewis/Bronsted acid and base catalysed reactions and related chemistry |
| Author | Vaghoo, Habiba Ebrahim |
| Author email | vaghoo@usc.edu; vaghoo@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program |
Chemistry vinyl fluorides |
| School | College of Letters, Arts and Sciences |
| Date defended/completed | 2008-06-24 |
| Date submitted | 2008 |
| Restricted until | Unrestricted |
| Date published | 2008-10-31 |
| Advisor (committee member) |
Olah, George A. Shing, Katherine S. |
| Abstract | This dissertation describes the development of new and practical methodologies for the synthesis of a broad variety of fluorinated heterocycles and vinyl fluorides via acid and base catalysis, respectively. It also describes efficient cyanosilylation of carbonyl compounds using a variety of nucleophilic catalysts.; Chapter 1 explores the rich history of fluorine and its compounds. Important milestones that have made a significant contribution to the field of chemistry are highlighted with emphasis on fluorine's role in medicinal chemistry. Methods to introduce fluorine are also included in this chapter.; Chapter 2 deals with the use of gallium (III) triflate as a versatile Lewis acid for the synthesis of different fluorinated heterocycles and α-aminonitriles. The condensation-cyclization reactions of various aromatic amino derivatives with fluorinated ketones to afford the corresponding fluorinated benzimidazolines, benzothiazolines, benzoxazolines, and dihydrobenzoxazinones, as well as fluorinated 1, 5 benzodiazepines and quinoxaline derivatives is described. Also included in this chapter are the syntheses of α-aminonitriles and their fluorinated analogs via the multicomponent Strecker reaction using gallium (III) triflate. Monofluoro-, difluoro-, or trifluoromethyl groups have been incorporated into both heterocycles and the α-aminonitrile products by varying the nature of the fluorinated ketones.; In Chapter 3, Nafion^®-H, a perfluoroalkanesulfonic acid resin, is shown to be a suitable solid acid catalyst with high selectivity and catalytic activity for the one-pot synthesis of fluorinated heterocycles. The Nafion-H mediated reactions are easily achieved under mild conditions in high yields and purity. Monofluoro, difluoro and trifluoromethylated derivatives can be prepared and its advantage as a solid superacid is highlighted by the recyclability studies.; Chapter 4 describes a new approach for the stereoselective synthesis of vinyl fluorides using α-substituted fluoro(phenylsulfonyl)methane derivatives under mildly basic reaction conditions. A variety of fluorovinyl sulfones as well as α-fluoro-α,β-unsaturated carbonyls can be synthesized to afford the E-isomer.; Finally, in Chapter 5, cyanosilylation of aldehydes and ketones using various nucleophilic catalysts under mild conditions is portrayed. Use of dimethylformamide (DMF) as solvent, afforded the trimethylsilylated cyanohydrins in good to excellent yields. K2CO3 and (MeO)2P(O)(O^-)(N^+Bu4)3 have been employed as the nucleophilic catalysts for the cyanosilylation using trimethylsilyl cyanide (TMSCN). |
| Keyword | fluorine chemistry; fluorinated heterocycles; fluorinated aminonitriles; cyanosilylation |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m1729 |
| Contributing entity | University of Southern California |
| Rights | Vaghoo, Habiba Ebrahim |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | cisadmin@lib.usc.edu |
| Filename | etd-Vaghoo-2053 |
| Archival file | uscthesesreloadpub_Volume44/etd-Vaghoo-2053.pdf |
Description
| Title | Page 113 |
| Contributing entity | University of Southern California |
| Repository email | cisadmin@lib.usc.edu |
| Full text | 99 chemical shifts were determined relative to internal tetramethylsilane at 0.0 ppm or to the 13C signal of CDCl3 at 77.0 ppm. The 19F NMR chemical shifts were determined relative to CFCl3 at 0.0 ppm as internal standard. Column chromatography was carried out using Sorbent 60, 65-250 mesh silica gel. TLC was performed on plastic backed silica plates (60F254, 0.2 mm) which were visualized using UV fluorescence and Iodine. 3.4.1 General Procedure 1,2-Phenylenediamine (216 mg, 2 mmol) was transferred to a 15 mL pressure tube equipped with a magnetic stirrer. To this was added NafionÒ-H powder (0.625g). The fluorinated ketone (2 mmol) was measured out separately in a 4 mL vial, dissolved in dichloromethane (3 mL) and the solution was transferred to the pressure tube. The tube was then closed and placed in a preheated oil bath (120 °C) with proper stirring. The progress of the reaction was monitored by 19F NMR and reaction was continued till the complete conversion of the fluoroketone. The reaction mixture was filtered and the catalyst was washed with dichloromethane successively and kept for recycling. The solvent was removed from the filtrate under reduced pressure to obtain the pure products, which were characterized by comparing their spectral data with those of the authentic samples. |
