Catalytic hydrogenation of unactivated amides enabled by hydrogenation of catalyst precursor

A general method for catalytic hydrogenation of unactivated amides was achieved. During the catalyst induction period, a novel structural change was observed involving full hydrogenation of the interior unsaturated bonds of the pyridines of the Ru-containing catalyst precursor. Based on this observation, the mechanism of amide hydrogenation may involve a two-step pathway, wherein the Ru catalyst having an H-Ru-N-H functionality is generated in the first step, followed by the amide carbonyl group interacting with the outer, rather than the inner, sphere of the Ru catalyst.