Rh(III)-Catalyzed Asymmetric Synthesis of Axially Chiral Biindolyls by Merging C-H Activation and Nucleophilic Cyclization

Enantiomeric access to pentatomic biaryls is challenging due to their relatively low rotational barrier. Reported herein is the mild and highly enantioselective synthesis of 2,3'-biindolyls via underexplored integration of C-H activation and alkyne cyclization using a unified chiral Rh(III) catalyst. The reaction proceeded via initial C-H activation followed by alkyne cyclization. A chiral rhodacyclic intermediate has been isolated from stoichiometric C-H activation, which offers direct mechanistic insight.