Aerobic cross-dehydrogenative coupling of toluenes and o -phenylenediamines by flavin photocatalysis for the facile synthesis of benzimidazoles.

Herein, we demonstrate a green atom-economical synthesis of benzimidazoles via the flavin-photocatalysed aerobic oxidative cross-dehydrogenative coupling of toluenes and o -phenylenediamines. The proposed metal-free reaction proceeds in methanol/H 2 O under visible light irradiation by consuming only molecular oxygen from atmospheric air and produces only water as waste.