Halogen–Metal Exchange Reactions with 2-Halogenoalkylsilicon Compounds

Abstract

2-Bromoethyltriphenylsilane undergoes extensive halogen–metal exchange with phenylmagnesium bromide in tetrahydrofuran, giving ethyltriphenylsilane and 1,4-bis(triphenylsilyl)butane as principal products. In diethyl ether the exchange reaction is suppressed and the main product is 2-phenylethyltriphenylsilane. With propylmagnesium bromide and ethylmagnesium bromide halogen–metal exchange occurs even in diethyl ether. It was concluded that some additional stability, not available to alkyl carbanions. was possessed by the carbanion Ph₃Si·CH₂·CH₂⁻.