Visible-light-driven semihydrogenation of alkynes via proton reduction over carbon nitride supported nickel

Semihydrogenation of alkynes represents one of the most viable route to produce functional alkene products. Herein we describe the visible-light-driven alcohol or water donating semihydrogenation catalyzed by nickel supported on carbon nitride scaffold (Ni/C 3 N 4 ) under ambient condition, exhibiting excellent alkene selectivity and broad substrate scope. The catalyst design takes advantage of C 3 N 4 to harvest visible irradiation and to tune the interaction of Ni with hydrogenation intermediates, which is essential for the excellent selectivity toward alkene products. The hydrogen atom incorporated in alkene products originates from hydroxyl group of methanol or water, via a Ni catalyzed proton reduction by photogenerated electrons to give the active surface hydrogen species (H*). Such hydrogenation pathway not only avoids harsh reaction condition but also enables facile synthesis of valuable deuterated alkenes using deuterated alcohols or D 2 O, promising enormous application potential for well-designed catalyst architectures in the light-driven selective transfer hydrogenation (deuteration) of alkynes and other organic substrates. Visible-light-driven Semihydrogenation of Alkynes via Proton Reduction over Carbon Nitride supported Nickel • Ni/C 3 N 4 catalyzes highly selective semihydrogenation of alkynes under visible light irradiation using alcohol or water as the hydrogen source. • C 3 N 4 plays an important role in depressing overhydrogenation, ensuring high selectivity of alkenes. • Active hydrogen species produced by proton reduction engage in semihydrogenation. • This protocol allows facile synthesis of valuable deuterated alkenes using readily available deuterated alcohols or D 2 O.