Complementary photochemical and electrochemical oxidation enables sustainable synthesis of benzimidazo[2,1-b]thiazoles from enaminones and 2-mercaptobenzimidazole.

Two complementary oxidative [3 + 2] cyclization protocols were developed for the synthesis of sulfur-containing benzimidazo[2,1-b]thiazole derivatives from enaminones and 2-mercaptobenzimidazole. The first method exploits visible-light-induced activation through an electron donor-acceptor (EDA) complex, using molecular oxygen as the sole oxidant for C-N and C-S bond formation, whereas the second relies on electrochemical oxidation in an undivided carbon-carbon cell under ambient air, avoiding metal catalysts, additives and stoichiometric chemical oxidants. Both one-step protocols provide high yields, broad substrate scope, excellent functional-group tolerance, short reaction times, scalability, and operational simplicity, offering practical and environmentally benign routes to benzimidazo[2,1-b]thiazole derivatives.