Substrate-Controlled Transformation of Azobenzenes to Indazoles and Indoles via Rh(III)-Catalysis

Rh(III)-catalyzed substrate-controlled transformation of azobenzenes to indazoles and 2-acyl (NH) indoles is achieved via C-H functionalization. Generally, good functional groups tolerance, satisfying yields, and excellent regio-selectivity are achieved in this reaction. Mechanistically, the reaction with acrylates undergoes beta-hydride elimination, while the reaction with vinyl ketones or acrylamides undergoes nucleophilic addition. Copper acetate was supposed to play different roles in the beta-hydride elimination to furnish indazoles and nucleophilic addition of C-Rh bond to deliver 2-acyl (NH) indoles.