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

Author: Chen, Hou

Year: 1997

Degree: Dissertation (Ph.D.)

Committee Member: Myers, Andrew G.

Option: Chemistry

DOI: 10.7907/wp2p-4s29

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.

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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