The Journal of Organic Chemistry

Highly selective generation and application of (E)-and (Z)-silyl ketene acetals from. alpha.-hydroxy esters

K Hattori, H Yamamoto

Index: Hattori, Kouji; Yamamoto, Hisashi Journal of Organic Chemistry, 1993 , vol. 58, # 20 p. 5301 - 5303

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Citation Number: 50

Abstract

Summary: A method for the stereoselective synthesis of silyl ketene acetals from a-hydroxy esters is described. Internal quench with excess TMSCl of the lithium enolate at-100" C, which is generated using a hindered base, LTMP, leads to the selective formation of (E)-silyl ketene acetal. In contrast, the deprotonation at-100" C using LHMDS in THF-HMPA (411, followed by treatment with tert-butyldimethylsilyl chloride affords the (Z)-silyl ketene acetal ...