Borane-Catalyzed Reductive α-Silylation of Conjugated Esters and Amides Leaving Carbonyl Groups Intact

Abstract

Described herein is the development of the B(C6F5)3- catalyzed hydrosilylation of a,b-unsaturated esters and amides to afford synthetically valuable a-silyl carbonyl products. The a-silylation occurs chemoselectively, thus leaving the labile carbonyl groups intact. The reaction features a broad scope of both acyclic and cyclic substrates, and the synthetic utility of the obtained a-silyl carbonyl products is also demonstrated. Mechanistic studies revealed two operative steps: fast 1,4- hydrosilylation of conjugated carbonyls and then slow silyl group migration of a silyl ether intermediate. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim