Visible-light-mediated external-reductant-free reductive cross coupling of benzylammonium salts with (hetero)aryl nitriles

Herein we report a novel visible-light-mediated external reductant-free reductive cross coupling for the construction of C sp2 – C sp3 bonds. A variety of benzylammonium salts underwent selective coupling with (hetero)aryl nitriles to deliver important diarylmethanes under mild reaction conditions. Importantly, photocatalysts can be omitted for many cases, which might involve the electron donor acceptor (EDA) complex. Mechanistic studies indicated benzylic radicals might be involved as the key intermediates. Moreover, the in situ generated NMe3 via cleavage of C–N bond in ammonium salts acts as the electron donor, thus avoiding the use of external-reductant.