Selective mono-arylation and -alkylation of bis(alkylthio)benzenes : The importance of steric effects in the nickel-catalyzed cross-coupling of aryl alkyl sulphides with grignard reagents

Abstract

Synthetically useful procedures to effect selective conversion of C-S into C-C bonds have been developed by taking advantage of the sensitivity of reactions of Grignard reagents with aryl alkyl sulphides, catalyzed by low-valent nickel species, to steric effects. It is shown that the course of these reactions is influenced by the steric requirements of both the aryl and the alkyl moieties of the sulphides. Thus, selective mono-arylation and alkylation of easily available bis(alkylthio)benzenes can be effected in medium to high yields. This allows the introduction of two different aryl or alkyl groups into the benzene nucleus by sequential substitution of the two alkylthio functions.