A Dual Cobalt‐Photoredox Catalytic Approach for Asymmetric Dearomatization of Indoles with Aryl Amides via C‐H Activation

Abstract

In this study, we unveil a novel method for the asymmetric dearomatization of indoles under cobalt/photoredox catalysis. By strategically activating C‐H bonds of amides and subsequent migratory insertion of p‐bonds present in indole as reactive partner, we achieve syn‐selective tetrahydro‐5H‐indolo[2,3‐c]isoquinolin‐5‐one derivatives with excellent yields and enantiomeric excesses of up to >99%. The developed method operates without a metal oxidant, relying solely on oxygen as the oxidant and employing an organic dye as a photocatalyst under irradiation. Control experiments and stoichiometric studies elucidate the reversible nature of the enantiodetermining C‐H activation step, albeit not being rate‐determining. This study not only expands the horizon of cobalt‐catalyzed asymmetric C‐H bond functionalization, but also showcases the potential synergy between cobalt and photoredox catalysis in enabling asymmetric synthesis of complex molecules.