Cobalt-catalyzed direct functionalization of indoles with isocyanides

Non-noble cobalt catalysts have been employed in various CH bond activation and functionalization in recent years. Herein, we report a cobalt-catalyzed CH activation and isocyanide insertion of 1H-indole-3-carboxamides for the divergent synthesis of two types of indole-containing molecules. Notably, the reaction with MgSO4 as the additive produces 1H-indole-2,3-dicarboxamides, while PivOK promotes the formation of 3-imino-3,4-dihydropyrrolo[3,4-b]indol-1(2H)-ones in moderate to high yields. Control experiments reveal that 3-imino-3,4-dihydropyrrolo[3,4-b]indol-1(2H)-ones is likely to be transformed to 1H-indole-2,3-dicarboxamides via the nucleophilic attack of H2O in the reaction system.