Asymmetric hydrogenations of ketones catalyzed by Ru-achiral phosphine-enantiopure diamine complexes

Five novel ruthenium complexes, RuCI2(MOTPP)(2)[(S,S)-DPEN] [MOTPP = tris(4-methoxyphenyl)phosphine] (1) RuCI2(TFTPP)(2)[(S,S)- DPEN] [TFTPP = tris(4-trifluoromethylphenyl)phosphine] (2), RuCI2(PPh3)(2)[(S,S)-DPEN] (3). RuCI2(BDPX)[(S,S)-DPFN] [BDPX = 1,2-bis(diphenylphosphinomethyl)benzene] (4), RuCI2(BISBI)[(S,S)-DPEN][BISBI=2.2'-bis(diphenylphosphinomethyl)-1.1'-biphenyl] (5) were synthesized and used for the hydrogenation of aromatic ketones. The complexes showed high catalytic activities, especially that the catalytic activity of complex 5 containing the diphosphine with large bite angle and complex 1 containing triarylphosphine with electron-donating group were higher than the other three complexes. The enantioselectivities of products were almost not influenced by the electron factors of phosphine. (c) 2005 Elsevier B.V. All rights reserved.