Palladium-Catalyzed Highly Regioselective Aromatic Substitution of Benzylic Ammonium Salts with Amines.

An unprecedented aromatic substitution reaction of benzylic ammonium salts has been developed through palladium-catalyzed C-N bond cleavage. A range of primary and secondary amines participated in a palladium-catalyzed aromatic substitution reaction of benzylic ammonium salts, delivering sterically hindered aromatic amines in moderate to excellent yields with extremely high regioselectivity. Preliminary mechanistic studies permitted successful identification of π-benzylpalladium complexes and γ-vinyl allylic amines as key intermediates. This study paves the way for the use of benzylic ammonium salts in the aromatic substitution reactions.