Non- C2-symmetrical antimony–phosphorus ligand, ( R/ S)-2-diphenylphosphano-2′-di( p-tolyl)stibano-1,1′-binaphthyl (BINAPSb): preparation and its use for asymmetric reactions as a chiral auxiliary

Abstract

A new non- C 2-symmetrical antimony–phosphorous ligand, (±)-2-diphenyl-phosphano-2′-di( p-tolyl)stibano-1,1′-binaphthyl (BINAPSb) 3 , has been prepared from 2-bromo-2′-diphenylphosphano-1,1′-naphthyl 4 via its borane complex 6 , and could be resolved by the separation of a mixture of the diastereomeric palladium complexes 8A and 8B derived from the reaction of (±)- 3 with optically active palladium reagent ( S)- 7 . The enantiomerically pure BINAPSb 3 has proved to be highly effective in the palladium-catalyzed asymmetric hydrosilylation of styrene as a chiral auxiliary.