Simple synthetic route to 4-aminobenzaldehydes from anilines

Abstract

Anilines unsubstituted at the 4-position react under mild conditions in Me₂SO–HCl solvent (H⁺= 0.6 mol dm^–3) to give substituted 4-aminobenzaldehydes in high yields; although addition of CuCl₂ gives a cleaner product, it is not essential for the reaction. Chloromethyl methyl sulfoxide is thought to be the active species in the reaction.