Stereo‐ and Regioselective Alkyne Hydrometallation with Gold(III) Hydrides

Abstract

The hydroauration of internal and terminal alkynes by gold(III) hydride complexes [(C^N^C)AuH] was found to be mediated by radicals and proceeds by an unexpected binuclear outer-sphere mechanism to cleanly form transinsertion products.R adical precursors such as azobisisobutyronitrile lead to ad rastic rate enhancement. DFT calculations support the proposed radical mechanism, with very lowa ctivation barriers,a nd rule out mononuclear mechanistic alternatives.T hese alkyne hydroaurations are highly regio-and stereospecific for the formation of Z-vinyl isomers,with Z/E ratios of > 99:1 in most cases.