Photoredox-Catalyzed Reductive Carbamoyl Radical Generation: A Redox-Neutral Intermolecular Addition-Cyclization Approach to Functionalized 3,4-Dihydroquinolin-2-ones.

The first reductive generation of carbamoyl radicals using photoredox catalysis for their formation is reported. This approach facilitated the development of a redox-neutral synthesis of functionalized 3,4-dihydroquinolin-2-ones via the novel intermolecular addition-cyclization of carbamoyl radicals across electron-deficient alkenes. To illustrate the versatility of this reaction, a diverse collection of 3,4-dihydroquinolin-2-ones, including fused cyclic and spirocyclic systems inspired by natural products, has been prepared.