Dynamic Kinetic Resolution: Asymmetric Transfer Hydrogenation of α-Alkyl-Substituted β-Ketoamides

Dynamic kinetic resolution (deracemization) of various alpha-alkyl-substituted beta-ketoamides 1 via asymmetric transfer hydrogenation proceeded efficiently to give the corresponding syn-beta-hydroxy amides 3 in high diastereo- and enantioselectivities. Specifically, subjection of 1 to HCO2H and Et3N in the presence of 0.5-1 mol % of pentafluorobenzenesulfonyl-DPEN-Ru catalyst 2b at 30-40 degrees C in either PhCH3 or CH2Cl2 generated the syn-hydroxy product 3 selectively in 15-33:1 dr, 93-97% ee, and 75-88% isolated yields.