Dimethyl Carbonate as a Methylating Agent. The Selective Mono-C-methylation of Alkyl Aryl Sulfones

Abstract

At 180–210 °C, α-methylene sulfones (both benzyl aryl and alkyl aryl sulfones, RCH ₂ SO ₂ AR: R = Ph, p-ClC ₆ H ₄ , Ar = Ph, p-ClC ₆ H ₄ , p-MeC ₆ H ₄ , and R = Me, Ar = Ph, p-ClC ₆ H ₄ , p-MeC ₆ H ₄ ) react with dimethyl carbonate to yield the corresponding mono-C-methyl derivatives [RCH(CH ₃ )SO ₂ Ar] in a selectivity >99%, at conversions of 76–99% (isolated yields: 97–92%).