Deprotonative Friedel–Crafts alkylation of arylsilanes with α-chlorosulfides

Abstract

Friedel–Crafts alkylation of trimethylphenylsilane with methyl chloro(methylthio)acetate in the presence of tin(IV) chloride gave a mixture of three regioisomers of methyl 2-(trimethylsilylphenyl)-2-(methylthio)acetates in which the meta- and para- isomers predominated. No ipso-substitution product was obtained. Based on the isomer distribution, the relative reactivity of the phenylsilane to benzene and the effects of the substituents on the orientation, it was suggested that in the Friedel–Crafts alkylation the trimethylsilyl group is a very slightly activating substituent on the benzene ring but has essentially no directing effect.