SYNTHESIS OF NEW CHIRAL PHOSPHINEPHOSPHITES HAVING 2-DIPHENYLPHOSPHINOBIPHENYL-2'-YL BACKBONE AND THEIR USE IN RH(I)-CATALYZED ASYMMETRIC HYDROFORMYLATIONS

New chiral phosphinephosphites (R)-(5,5'-dichloro-2-diphenylphosphino-4,4',6,6'-tetramethylbiphenyl-2'-yl)((S)-1,1'-binaphthalen-2,2'-diyl)phosphite [abbreviated (R,S)-BIPHEMPHOS] and its enantiomer (S,R)-BIPHEMPHOS have been synthesized from 5,5'-dichloro-4,4',6,6'-tetramethyl-2,2'-biphenyldiol in enantiomerically pure form. Their Rh(I) complexes have been shown to be highly efficient catalysts for asymmetric hydroformylations of a variety of olefinic substrates. The corresponding phosphinephosphites derived from 2,2'-biphenyldiol were also tested as ligands for asymmetric hydroformylation.