Selective ortho-methylthiomethylation of phenols with dimethyl sulphoxide and thionyl chloride

Abstract

Thionyl chloride and phenyl chlorosulphinate have been shown to be useful activators for dimethyl sulphoxide in the selective preparation of ortho-methylthiomethylphenol via a [2,3]sigmatropic rearrangement. By this process, ortho-methylthiomethylated phenols having a variety of 2- or 4-substituents (Me, Cl, OMe, NO₂, and CO₂Me) have been prepared in good yields. In contrast, similar reactions of 3-substituted phenols were affected by the electronic characters of the substituents. With more electron-donating groups such as OH and OMe in the 3-position, none of the expected products were obtained, but in the case of other 3-substituted phenols, two possible rearrangement products were obtained in moderate yields.