Self-modulated highly chemoselective direct-reductive-amination (DRA) of benzaldehydes straightforward to N-monosubstituted benzylamine hydrochlorides

An unprecedented efficient and chemoselective DRA of benzaldehydes and primary amines was developed to directly yield N-monosubstituted benzylamine hydrochlorides as single products in practically quantitative yields. The method was characterized by simply adding a few milliliters of CHCl3 in the conventional Pd–C catalytic hydrogenation system at atmospheric pressure and room temperature. A self-modulated system and a four-stage cyclic pathway were proposed.