Iron-Catalyzed C−H Alkylation/Ring Opening with Vinylbenzofurans Enabled by Triazoles

We report an unprecedented iron-catalyzed C−H annulation using readily available 2-vinylbenzofurans as the reaction pattern. The redox-neutral strategy, based on cheap, non-toxic, and earth-abundant iron catalysts, exploits triazole assistance to promote a cascade C−H alkylation, benzofuran ring-opening and insertion into a Fe−N bond, to form highly functionalized isoquinolones. Detailed mechanistic studies supported by DFT calculations fully disclosed the manifold of the iron catalysis.