A Molecular Model To Explain and Predict the Stereoselectivity in Rhodium-Catalyzed Hydroformylation

Abstract

By example of the bidentate phosphine−phosphite ligand BINAPHOS 1, [(2-diphenylphosphino)-1,1‘-binaphthalen-2‘-yl)(1,1‘-binaphthalen-2,2‘-diyl)phosphite], a semiquantitative theoretical model elucidates the origin of stereodifferentiation in rhodium-catalyzed hydroformylation. It is demonstrated that the outstanding properties of 1 are due to the synergistic combination of three factors: (i) pronounced coordination preferences for steric and electronic reasons; (ii) adequate number of chirality centers; (iii) correct configuration of the binaphthyl fragments. The model is, in principle, applicable to all kinds of bidentate phosphine ligands.