Dynamic Kinetic Resolution of α-Keto Esters via Asymmetric Transfer Hydrogenation

The dynamic kinetic resolution of β-aryl α-keto esters has been accomplished using a newly designed (arene)­RuCl­(monosulfonamide) transfer hydrogenation catalyst. This dynamic process generates three contiguous stereocenters with remarkable diastereoselectivity through a reduction/lactonization sequence. The resulting enantioenriched, densely functionalized γ-butyrolactones are of high synthetic utility, as highlighted by several secondary derivatizations.