摘要:
New optically active diphosphine ligands, (S)-2,2'-bis(diphenylphosphino)-3,3',4,4',5,5',6,6'-octamethylbiphenyl (2a) and (S)-2,2'-bis(diethylphosphino)-3,3',4,4',5,5',6,6'-octamethylbiphenyl (2c) were prepared via optical resolution of the corresponding phosphine oxides. The Rh complex of 2c proved efficient in the catalytic asymmetric hydrogenation of a dehydroamino acid derivative even at -50degreesC and gave 88% e.e. of hydrogenation product quantitatively. (C) 2002 Elsevier Science B.V. All rights reserved.