Dendritic [RuCl2(BINAP)(DPEN)] catalysts with 'Sandwich' multi-layer structure for asymmetric hydrogenation of simple aryl ketones

A new kind of chiral dendritic [RuCl2(BINAP)(DPEN)] catalysts with a 'Sandwich' multi-layer structure have been synthesized via metal coordination reactions with dendritic chiral diphosphines and dendritic chiral diamine ligands. The formation of the dendritic catalysts was confirmed by P-31 NMR. The catalyst performance was then investigated in the asymmetric hydrogenation of simple aryl ketones, and comparable enantioselectivities were achieved with comparison to that of the corresponding small-molecular catalyst. In addition, the recyclable property of these homogeneous catalysts was studied with the third-generation catalyst, which was reused nine times by simple solvent precipitation without any loss of enantioselectivity. (C) 2013 Elsevier B. V. All rights reserved.