Transformation of alkylated pseudoephedrine amides to highly enantiomerically enriched carboxylic acids and ketones

Citation

Chen, Hou (1997) Transformation of alkylated pseudoephedrine amides to highly enantiomerically enriched carboxylic acids and ketones. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/wp2p-4s29. https://resolver.caltech.edu/CaltechETD:etd-01082008-105201

Abstract

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The noncatalyzed aldol addition of [...]-methylsilacyclobutane-[...],[...]-ketene acetals to aldehydes and the transformation of alkylated pseudoephedrine amides to highly enantiomerically enriched carboxylic acids and ketones are described. In Chapter 1, constraining of the silicon atom of an [...]-silyl ketene-[...],[...]-acetal within a four-membered ring is shown to greatly accelerate the rate of its noncatalyzed aldol addition to aldehydes and ketones. This reaction is highly syn selective and is proposed to proceed through a boat transition state involving pentacoordinate silicon. In Chapter 2, the preparation of carboxylic acids and ketones from alkylated pseudoephedrine amides is described. Acidic, basic, and slightly acidic metal-mediated hydrolysis conditions have been developed. In addition, the treatment of alkylated pseudoephedrine amides with alkyllithium reagents is shown to be a practical method for the preparation of highly enantiomerically enriched ketones.

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