Redox-Active Bis(arylimino)acenaphthene-Catalyzed Dehydrogenative Aerial Functionalization of Alcohols to N-Heterocycles Under Exposure of Visible Light

An environmentally benign, transition-metal-free catalytic method has been developed for the synthesis of important classes of bioactive N-heterocycles, including quinoline, quinazoline, and quinazolinone under exposure of blue light. In this method, benzylic alcohol derivatives are catalytically dehydrogenated to the corresponding aldehydes by a redox-active molecule known as bis(arylimino)acenaphthene (Ar-BIAN) under exposure of blue light, and subsequently they react with ketones, nitriles, and amide partners. By using aerial-O₂ as a terminal oxidant, a variety of heavily functionalized N-heterocycles have been successfully synthesized with good to excellent yields across 59 examples. The organocatalyst used in this method demonstrates high compatibility and selectivity compared to previously reported transition metal catalysts. A plausible mechanistic path for the current protocol by combining structural, electrochemical, and photophysical properties, spectroscopic results, various control experiments, and detailed theoretical calculations is proposed.