Use of 1-Chlorovinyl p-Tolyl Sulfoxides as Alkynylmagnesium Chloride Sources

Abstract

A method for generating alkynylmagnesium chlorides from 1-chlorovinyl p-tolyl sulfoxides and an isopropylmagnesium chloride-lithium chloride complex (turbo Grignard reagent) has been developed. The method consists of a sulfoxide/magnesium exchange reaction of 1-chlorovinyl p-tolyl sulfoxides and a turbo Grignard reagent, a FritschButtenbergWiechell rearrangement of the resulting magnesium alkylidene carbenoids, and a deprotonation of terminal alkynes with a turbo Grignard reagent. The resulting alkynylmagnesium chlorides are reacted with a variety of electrophiles to generate internal alkynes.