Solvent-Mediated Tunable Regiodivergent C6- and N1-Alkylations of 2,3-Disubstituted Indoles with p -Quinone Methides.

Indium-catalyzed, solvent-enabled regioselective C6- or N1-alkylations of 2,3-disubstituted indoles with para -quinone methides are developed under mild conditions. Notably, highly selective and switchable alkylations were selectively achieved by adjusting the reaction conditions. Moreover, scalability and further transformations of the alkylation products are demonstrated, and this operationally simple methodology is amenable to the late-stage C6-functionalization of the indomethacin drug. The reaction pathways were explained with the support of experimental and density functional theory studies.