Heterogeneization of a new Ru(II) homogeneous asymmetric hydrogenation catalyst containing BINAP and the N-tridentate bpea ligand, through covalent attachment on amorphous AlPO4 support

Abstract

Following a new methodology to obtain hybrid organic–inorganic solids, the homogeneous complex [RuII(bpea) {(S)(−)(BINAP)}Cl](BF4), (bpea = N,N-bis(2-pyridylmethyl)ethylamine and BINAP = 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl) has been covalently immobilized on an AlPO4 amorphous solid. It was tested in the successive liquid phase enantioselective hydrogenation of several prochiral substrates such us dimethyl itaconate, methyl 2-acetamidoacrylate and methyl 2-acetamidocinnamate, in CH2Cl2 as solvent, ([subs]/[cat] = 0.016/0.000352 = 45.4), hydrogen pressure 6.8 atm and 50–70 °C reaction temperatures. Results obtained indicate that the catalytic activity with a high enantioselectivity (99%) was maintained throughout 10 successive reactions. Furthermore, the immobilized catalyst was easily recovered when repeatedly used and handled for several days, under the same experimental conditions as those in a conventional heterogeneous supported Ru catalyst.