Enantiomeric ligands of phosphorus made

Abstract

Chemists at Harvard University have devised asymmetric syntheses of enantiomeric phosphine ligands, chiral at phosphorus, to make asymmetric reaction catalysts [ J. Am. Chem. Soc , 115, 11000 (1993)]. The Harvard achievement avoids resolutions of racemates, which result in 50Vc of the synthesized material being an unwanted enantiomer. The Harvard chemists note the importance of having suitable chiral phosphine or diphosphine ligands in development of transition-metal catalysts for enantioselective reactions, especially hydrogenation processes. The new method allows chemists to choose the absolute configuration of the product phosphine in advance, and also to decide which of two phosphine enantiomers to synthesize. Moreover, enantiomeric excesses are higher than 97%. And the method is so general that it makes available a wide variety of phosphine ligands, which in turn will lead to even further development of enantioselective catalysts. Organic chemistry professor Elias J. Corey and postdoctoral fellows Zh...