Ruthenium(II) N-heterocyclic carbene complexes in the transfer hydrogenation of ketones

Six ruthenium-N-heterocyclic carbene complexes (2-7) have been prepared and the new compounds characterized by C, H, N analyses, H-1-n.m.r. and C-13-n.m.r. The reduction of ketones to alcohols via transfer hydrogenation was achieved with catalytic amounts of complexes (2-7) in the presence of t-BuOK.