Asymmetric hydrogenation, hydroformylation and hydrocarbalkoxylation of olefins by transition metal complexes with steroidal phosphines

Abstract

Two new optically active phosphines, 3α-diphenylphosphino-5α-cholestane [(+)-DICOL] and 2,3- O-(5′α-cholestan-3′,3′-ylidene)-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane [(−)-DIOCOL] have been prepared and used as ligands in transition metal catalyzed asymmetric processes. In CO-insertion reactions, especially in the Pd promoted hydrocarbalkoxylation,(+)-DICOL-based complexes displayed a remarkable catalytic activity and a very high regioselectivity, but a poor stereoselectivity. Optical yields of up to 93% and up to 34%, respectively, were obtained in asymmetric hydrogenation and hydroformylation catalyzed by rhodium complexes with (−)-DIOCOL.