Efficient heterogeneous catalytic systems for enantioselective hydrogenation of prochiral carbonyl compounds

Abstract

A proficient heterogeneous catalyst system for stereoselective hydrogenation of carbonyl compounds was synthesized, involving anchoring of Ru II–phosphine–diamine complexes on the inner surfaces of organo-functionalized mesoporous MCM-41 and MCM-48 materials. Powder XRD and TEM experiments reveal highly ordered hexagonal and cubic patterns of the organically modified MCM-41 and MCM-48 materials, respectively, even after incorporation of Ru complexes. Moreover, the integrity of the Ru complexes was retained after anchoring into the mesoporous hosts, which was supported from FTIR, 31P CP MAS NMR, and XPS analyses. This new heterogeneous catalyst shows promising activity and selectivity in the enantioselective hydrogenation of prochiral ketones. The effects of reaction time, temperature, and hydrogen pressure on the catalytic activity and enantioselectivity were studied in detail. As high as 95–99% ee could be obtained using these solid catalysts under heterogeneous reaction conditions. The anchored solid catalysts can be recycled effectively and reused several times without any loss in activity and selectivity.