Date of Award

1-1-2013

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

Chemistry

First Advisor

Sheryl L Wiskur

Abstract

Described herein is the first enantioselective silylation based kinetic resolution of monofunctional secondary alcohols to achieve useful levels of enantioselectivity. Using commercially available reagents, the reaction conditions were optimized and found to successfully resolve several secondary alcohols with high enantioselectivity. It was discovered that the nucleophilic isothiourea compound (-)-tetramisole, with Ph3SiCl as the silyl source, gave superior results to other nucleophilic catalysts and was capable of performing the kinetic resolution in as little as 45 minutes using mild reaction conditions. The structural and electronic characteristics of successful and less successful substrates are also discussed.

Chapter three discusses mechanistic investigations and the characterization of the reactive silylating compounds for the enantioselective silylation of monofunctional secondary alcohols with (-)-tetramisole and other nucleophiles. Solid state and solution based 1H and 29Si NMR techniques were utilized as well as a modified 1H-29Si gHSQC NMR technique. Evidence to support a tetravalent silicon intermediate between (-)-tetramisole and Ph3SiCl is presented. Then, circular dichroism studies were performed on some chiral silyl ethers to see if a nearby chiral center can cause the aryl groups to favor a single helical conformation. Chapter four presents the synthesis and structural characteristics of chiral 2-pyridyloxazolidine and 2,6-pyridylbisoxazolidine compounds. These compounds were found to be viable ligands in the formation of metal complexes. Their ability to behave as colorimetric sensors for chiral monofunctional alcohols and amines is also reported. In addition, their use as an organocatalyst for the kinetic resolution of secondary alcohols by enantioselective silylation is also discussed.

ourea compound (-)-tetramisole, with Ph3SiCl as the silyl source, gave superior results to other nucleophilic catalysts and was capable of performing the kinetic resolution in as little as 45 minutes using mild reaction conditions. The structural and electronic characteristics of successful and less successful substrates are also discussed.

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Chemistry Commons

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