Thioether-Assisted Cu-Catalyzed C5–H Arylation of Imidazo[1,5‑a]pyridines

A Cu-catalyzed regioselective C5–H arylation of imidazo­[1,5-a]­pyridines with aryl iodides was achieved with the assistance of an ethylthio group at the C3 position. This directing group could be easily removed to furnish a range of 5-(hetero)­arylimidazo­[1,5-a]­pyridine derivatives. The reaction tolerates a variety of functionalities and is compatible with sterically hindered substrates.