Diametric Stereocontrol in Dynamic Catalytic Reduction of Racemic Acyl Phosphonates: Divergence from α-Keto Ester Congeners

An unexpected dichotomy was observed in the Ru-catalyzed asymmetric transfer hydrogenation of acyl phosphonates: reduction proceeded from the opposite face relative to that observed in the analogous reduction of alpha-keto esters. The first highly selective catalytic hydrogenation of acyl phosphonates was utilized in the dynamic kinetic resolution of alpha-aryl acyl phosphonates, providing beta-stereogenic alpha-hydroxy phosphonic acid derivatives.