Link to DOI – 10.1002/anie.202204400
Angew. Chem. Int. Ed. 2022, 61, e2022044
Direct dearomative C3-functionalization of indoles provided access to privileged scaffolds by an umpolung strategy. Against all odds, C3-indolium intermediates could be generated from NH-indoles under operationally simple conditions with triflic acid at room temperature to promote intra- and intermolecular C3-regioselective hydroarylation. DFT studies suggest that these cationic or dicationic intermediates could be stabilized by H-bonded clusters.