Tandem Photoredox-Chiral Phosphoric Acid Catalyzed Radical–Radical Cross-Coupling for Enantioselective Synthesis of 3‑Hydroxyoxindoles

A photochemical protocol that couples diarylamines and α-ketoesters to afford the chiral 3-hydroxyoxindoles through tandem photoredox and chiral phosphoric acid catalysis is developed. The reaction involves an enantioselective photochemical radical–radical cross-coupling process. The chiral phosphoric acid is discovered to play crucial roles by decreasing the reductive potentials of α-ketoesters and stereocontrolling the downstream asymmetric radical–radical cross-coupling via the formation of pentacoordinate complex.