Applications of α-Keto Carbocations in Carbon-Carbon and Carbon-Nitrogen Bond Formation

This thesis describes synthetic applications of α-keto carbocations, which represent potentially useful, but poorly studied, reversed polarity equivalents of enolates. In the first chapter, a Ag(I) – mediated method for the nucleophilic displacement of α-halocarbonyl compounds to construct carbon-ca...

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Bibliographic Details
Main Author: Lai, Ping Shan
Other Authors: Taylor, Mark S.
Language:en_ca
Published: 2011
Subjects:
Online Access:http://hdl.handle.net/1807/32798
Description
Summary:This thesis describes synthetic applications of α-keto carbocations, which represent potentially useful, but poorly studied, reversed polarity equivalents of enolates. In the first chapter, a Ag(I) – mediated method for the nucleophilic displacement of α-halocarbonyl compounds to construct carbon-carbon bonds is described. The highly electrophilic nature of the putative α-keto carbocation intermediates enables the use of relatively unreactive nucleophiles in both intra- and intermolecular contexts. Such intermediates also present interesting opportunities for stereocontrol: our efforts to carry out diastereoselective additions to chiral α-keto carbocations are described. Oxazoles are an important class of heterocycles, and several syntheses are addressed in Chapter 2. Our approach to this class of compounds employs a TMSOTf mediated Ritter reaction to construct the carbon-nitrogen bond. Cycloaddition of 2-alkoxyoxazoles with alkynes presents a facile route for furan synthesis. The final chapter describes our attempts to apply anion-π interaction in organocatalysis. These interactions between anions and electron-deficient arenes have been characterized in some detail and have recently been applied in ion transport. Applications of prolinol-based secondary amines incorporating electron-deficient aromatic groups are described.