Diastereo- and Enantioselective anti-Selective Hydrogenation of α-Amino-β-keto Ester Hydrochlorides and Related Compounds Using Transition-Metal-Chiral-Bisphosphine Catalysts

This review describes our recent works on the diastereo- and enantioselective synthesis of anti-beta-hydroxy-alpha-amino acid esters using transition-metal-chiral-bisphosphine catalysts. A variety of transition metals, namely ruthenium (Ru), rhodium (Rh), iridium (Ir), and nickel (Ni), in combination with chiral bisphosphines, worked well as catalysts for the direct anti-selective asymmetric hydrogenation of alpha-amino-beta-keto ester hydrochlorides, yielding anti-beta-hydroxy-alpha-amino acid esters via dynamic kinetic resolution (DKR) in excellent yields and diastereo- and enantioselectivities. The Ru-catalyzed asymmetric hydrogenation of alpha-amino-beta-ketoesters via DKR is the first example of generating anti-beta-hydroxy-alpha-amino acids. Complexes of iridium and axially chiral bisphosphines catalyze an efficient asymmetric hydrogenation of alpha-amino-beta-keto ester hydrochlorides via dynamic kinetic resolution. A homogeneous Ni-chiral-bisphosphine complex also catalyzes an efficient asymmetric hydrogenation of alpha-amino-beta-keto ester hydrochlorides in an anti-selective manner. As a related process, the asymmetric hydrogenation of the configurationally stable substituted alpha-aminoketones using a Ni catalyst via DKR is also described.