Kinetic Resolution of Heterocyclic Lactams by a Photocatalytic Cobalt-Catalyzed Dehydrogenation

Chiral heterocyclic lactams have been kinetically resolved in a photochemical process that involves selective hydrogen abstraction by a chiral benzophenone catalyst. Recognition of one enantiomer is achieved by a two-point hydrogen bonding interaction that directs the reactive carbonyl group of the photocatalyst to the C–H bond at the stereogenic center within the lactam. The generated radical is converted to an oxidized product in a cobaloxime-catalyzed dehydrogenation reaction. The unreactive enantiomer is retained and isolated in enantiomerically enriched form (21 examples, 31–56% yield, 90–99% ee).