Hydroarylation of alkynes catalyzed by nickel.

Nickel catalysts derived from bis(1,5-cyclooctadiene)nickel [Ni(cod)(2)] and trialkylphosphines effect hydroarylation of alkynes through functionalization of C-H bonds of arenes including benzo-fused five-membered heteroarenes, pyridine-N-oxides, pyridines, 2-pyridones, and perfluoroarenes. The reactions proceed with excellent stereo- and regioselectivity to give disubstituted arylethenes in good yields. Use of Lewis acid (LA) co-catalysts is crucial for success in reactions of imidazoles, pyridines, and 2-pyridones; it is possible that coordination of the LA to the nitrogen or oxygen functionalities of such substrates increases the reactivity of their C-H bonds towards nickel(0) species.