Asymmetric Aerobic Intramolecular Dearomative ortho Coupling of Tethered Phenols by Chromium-Salen Complex/Nitroxyl Radical Catalysis

Abstract

Herein, we report the catalytic asymmetric intramolecular dearomative coupling of tethered phenols in ortho-para fashion under aerobic conditions. Cooperative catalysis with a chromium-salen complex/nitroxyl radical enabled the desired transformation to proceed at ambient temperature under oxygen atmosphere. A range of tethered phenols were efficiently converted into spirocyclic 2,4-dienones in moderate to good yields and enantioselectivities (up to 68% enantiomeric excess (ee)).