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 α-keto esters. The first highly selective catalytic hydrogenation
of acyl phosphonates was utilized in the dynamic kinetic resolution
of α-aryl acyl phosphonates, providing β-stereogenic α-hydroxy
phosphonic acid derivatives.