New non-C2-symmetric phosphine-phosphonites as ligands in asymmetric metal catalysis
作者:Manfred T Reetz、Andreas Gosberg
DOI:10.1016/s0957-4166(99)00215-3
日期:1999.6
Starting from 1,2-dibromobenzene, the synthesis of N,N,N'-N'-tetraethyl-[2-(diphenylphosphino)phenyl]phosphonous acid tetraamide is possible in two simple steps. This key compound reacts with a variety of chiral diols such as (R)- and (S)-binaphthol, 1,2:5,6-diisapropylidene-D-mannitol or (1R,2R)-1,2-diphenyl-1,2-ethane diol to form the corresponding non-C-2-symmetric phosphine-phosphonite compounds. These ligands react with Rh(COD)(2)BF4 to form bidentate Rh-complexes which serve as catalysts in the asymmetric hydrogenation of dimethyl itaconate with ee values of up to 88%. (C) 1999 Elsevier Science Ltd. All rights reserved.