Synthesis of Multi-Substituted Cyclobutanes and Alkylidenecyclobutanes by the Reaction of Cyclobutylmagnesium Carbenoids with Nucleophiles

Abstract

Treatment of 1-chlorocyclobutyl p-tolyl sulfoxides with Grignard reagents such as ethylmagnesium chloride, isopropylmagnesium chloride, and cyclopentylmagnesium chloride in THF at low temperature gave cyclobutylmagnesium carbenoids in high yields. The generated magnesium carbenoids were found to be stable at -78 ˚C for at least 30 minutes. The cyclobutylmagnesium carbenoids reacted with several nucleophiles to give multi-substituted cyclobutanes. The reaction of the cyclobutylmagnesium carbenoids with lithium α-sulfonyl carbanions afforded alkylidenecyclobutanes in moderate to good yields.