New non-C-2-symmetric phosphine-phosphonites as ligands in asymmetric metal catalysis

Starting from 1,2-dibromobenzene, the synthesis of N,N,N'-N'-tetraethyl-[2- (diphenylphosphino)phenyl]phosphonous acid tetraamide is possible in two si mple 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 phos phine-phosphonite compounds. These ligands react with Rh(COD)(2)BF4 to form bidentate Rh-complexes which serve as catalysts in the asymmetric hydrogen ation of dimethyl itaconate with ee values of up to 88%. (C) 1999 Elsevier Science Ltd. All rights reserved.