Highly Selective Hydrogenation Of C=C Bonds Catalyzed By A Rhodium Hydride

Under mild conditions (room temperature, 80 psi of H-2) Cp*Rh(2-(2-pyridyl)phenyl)H catalyzes the selective hydrogenation of the C=C bond in alpha,beta-unsaturated carbonyl compounds, including natural product precursors with bulky substituents in the beta position and substrates possessing an array of additional functional groups. It also catalyzes the hydrogenation of many isolated double bonds. Mechanistic studies reveal that no radical intermediates are involved, and the catalyst appears to be homogeneous, thereby affording important complementarity to existing protocols for similar hydrogenation processes.