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

Abstract

Dynamic kinetic resolution (deracemization) of various α-alkyl-substituted β-ketoamides 1 via asymmetric transfer hydrogenation proceeded efficiently to give the corresponding syn-β-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 °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.