Visible Light-Induced Energy Transfer Mediated Regioselective C-3 Thiolation of Imidazoheterocycles using Bunte Salts.

An external-photocatalyst-free visible light-induced regioselective C-3 sulfenylation of imidazo[1,2-a]pyridines using Bunte salts has been accomplished via C(sp2)-H functionalization. This protocol allows the coupling of a wide range of imidazoheterocycles with alkyl-, benzyl-, and aryl Bunte salts under ambient air as the sole oxidant. The radical scavenging, UV-visible spectroscopic studies, and Stern‒Volmer experiments revealed that the reaction occurs through energy transfer followed by a radical SET pathway.