Nickel-Catalyzed Inter- and Intramolecular Reductive Cross-Coupling Reactions of Arylbenzylammonium Salts through Highly Site-Selective C-N Bond Cleavage

The site selectivity has been investigated for the C-N bond cleavage of arylbenzylammonium salts in reductive cross-coupling reactions with carbon electrophiles. A wide variety of arylbenzylammonium triflates participated in nickel-catalyzed zinc-mediated benzyl-aryl cross-electrophile coupling with aryl bromides to afford diarylmethanes with extremely high site selectivity. The same reaction conditions were successfully extended to the intramolecular reductive cross-coupling of benzyl(bromoaryl)ammonium triflates. Moreover, arylbenzylammonium triflates underwent nickel-catalyzed manganese-mediated benzyl-acyl cross-electrophile coupling with aromatic carboxylic acids in the presence of di-tert-butyl pyrocarbonate. These reactions employ readily available feedstocks and reagents, exhibit extremely high site selectivity for the cleavage of benzylic C-N bonds rather than aromatic C-N bonds, and tolerate a variety of functional groups.