Asymmetric Hydrogenation of alpha-Keto Phosphonates with Chiral Palladium Catalysts

摘要

Under atmospheric hydrogen pressure, a catalytic amount of palladium(II) trifluoroacetate and (R)-MeO-BIPHEP in 2,2,2-trifluoroethanol promoted the asymmetric hydrogenation of diisopropyl a-keto phosphonates 1 to afford the corresponding alpha-hydroxy phosphonates 2 in excellent yields and with a moderate enantioselectivities of up to 55% ee. Racemic alpha-aryl-alpha-hydroxy phosphonates can be prepared by using palladium on carbon as the catalyst. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)