Co(III)-Catalyzed Chemo- and Regioselective C2-Functionalization of N-Carboxamide Indoles via an Oxidizing Directing Group Strategy.

A cobalt-catalyzed [4 + 1] annulation of N-carboxamide indoles with activated alkenes has been developed via an oxidizing directing group strategy. This protocol provides access to highly valuable indole-fused imidazolidinone scaffolds in moderate to excellent yields. The scope of the methodology was extensively explored using various acrylate derivatives and vinyl acetamide. Furthermore, the reaction was extended to allyl acetate and vinylcyclopropanes as coupling partners, resulting in the formation of C2-functionalized allylated products in moderate to good yields. Mechanistic investigations were performed, and a plausible reaction mechanism was proposed to account for the observed transformations.