Development of a New Six-Membered Chelating Chiral [Bisphosphine] rhodium Catalyst and Efficient Asymmetric Hydrogenation of (Z)-2-Acetamidocinnamic Acid¹

Abstract

A new 1,3-substituted bisphosphine ligand, (1R, 2R)-1- diphenylphosphino - 2- (diphenylphosphinomethyl) - cyclopentane (R,R)-PPCP, was prepared in four steps from ethyl 2-oxocyclopentanecarboxylate. (R,R)-PPCP was designed to form the favorable skew conformation of the six-membered chelate with rhodium. Its rhodium complex was found to be one of the most efficient catalysts for asymmetric catalytic hydrogenation of amino acid precursors such as (Z)-2-acetamidocinnamic acid.