Rhodium complexes with a new chiral nitrogen-containing BINOL-based diphosphite or phosphonite ligand: synthesis and application to hydroformylation of styrene and/or hydrogenation of prochiral olefins

Abstract

Two new cationic rhodium(I) complexes with a chiral nitrogen-containing BINOL-based diphosphite or phosphonite ligand have been synthesized. Chiral diphosphite was prepared by the reaction of N-phenyldiethanolamine with two equivalents of [(R)-(1,1′-binaphthalene-2,2′-diyl)]chlorophosphite. In its rhodium complex the ligand is bound to the metal via both phosphorus atoms, and a Rh–N interaction is also possible. Synthesis of the chiral phosphonite was achieved by the reaction of 2-(N,N-dimethylaminophenyl)-bis(diethylamino)phosphine with one equivalent of R-BINOL. In its rhodium complex, the ligand is P,N-bonded, forming a five-membered chelate ring. The first complex was applied to hydroformylation of styrene and displayed high activity and chemo- and regioselectivity, but unfortunately no asymmetric induction was found. Both complexes were evaluated in the hydrogenation of prochiral olefins with moderate activities and low enantioselectivities. Copyright © 2005 John Wiley & Sons, Ltd.