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

A photochemical protocol that couples diarylamines and alpha-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 alpha-ketoesters and stereocontrolling the downstream asymmetric radical-radical cross-coupling via the formation of pentacoordinate complex.

Automated summary

A photochemical protocol is developed for the synthesis of chiral 3-hydroxyoxindoles by coupling diarylamines and alpha-ketoesters using tandem photoredox and chiral phosphoric acid catalysis. The chiral phosphoric acid plays a crucial role in controlling the stereochemistry of the downstream radical-radical cross-coupling process.