Complete Chiral Induction from Enantiopure 1,2‐Diamines to Benzophenone‐Based Achiral Bisphosphane Ligands in Noyori‐Type RuII Catalysts

Abstract We report the design and synthesis of a novel class of Ru II catalysts ( 3 ) composed of achiral benzophenone‐based bisphosphane ligands and enantiopure 1,2‐diamines for the asymmetric hydrogenation of aryl ketones. The developed catalysts show excellent enantioselectivities (up to 97 % ee ) and activities (up to S/C = 10,000) in the hydrogenation of a variety of aromatic ketones.Complete chiral induction from the enantiopure 1,2‐diamine to the achiral bisphosphane ligand was observed. The coordination of the C=O moiety in 3 to the cationic Ru II center is considered to be of key importance in providing a higher thermodynamic and kinetic rotation barrier for the flexible bisphosphane ligand, resulting in the preferential formation of only one diastereomer, and thus explaining the high enantioselectivity of the catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)