Relay Organophotoredox/N‑Heterocyclic Carbene Catalysis-Enabled Asymmetric Synthesis of Dibenzoxazepine-Fused Pyrrolidinones

An unprecedented highly stereoselective synthesis of pyrrolo­[1,2-d]­[1,4]­oxazepin-3­(2H)-ones has been accomplished via photoredox/N-heterocyclic carbene (NHC) relay catalysis. A wide range of substituted dibenzoxazepines and aryl/hetereoaryl enals were well accommodated under the organic photoredox catalysis-promoted amine oxidation to generate the imines, followed by a NHC-catalyzed [3 + 2] annulation reaction to achieve excellent diastereo- and enantioselectivities of the dibenzoxazepine-fused pyrrolidinones.