Regio- and Stereoselective Approach to 1,2-Di-and 1,1,2-Trisilylethenes by Cobalt-Mediated Reaction of Silyl-Substituted Dibromomethanes with Silylmethylmagnesiuni Reagents

摘要

Vinylsilanes are useful organometallic reagents in organic synthesis because the C(sp~2)-Si bonds undergo numerous transformations.'11 Multiply silylated ethenes are thus likely to represent platforms for a variety of highly substituted ethenes.Moreover,multiply silylated ethenes themselves attract considerable attention from the viewpoint of structural organic chemistry.'2' Despite their importance,there is a limited number of access routes to multiply silylated ethenes.Hydrosilylation of silylacetylenes'3' and bissilylation of acetylenes'4' are most convenient procedures.'5' Scheme 1 (top) shows representative approaches,for instance,to trisilyl-ethenes with three different silyl groups.However,difficulties are often encountered in such synthetic strategies in terms of regioselectivity and the occurrence of several side reactions.