Organocatalytic Triazole Formation, Followed by Oxidative Aromatization: Regioselective Metal-Free Synthesis of Benzotriazoles

Herein we report on our studies on the sequential one‐pot combinations of amine‐catalyzed multicomponent reactions (MCRs). We have developed the copper‐free synthesis of functionalized bicyclic N‐aryl‐1,2,3‐triazole and N‐arylbenzotriazole products 4 and 5 from the simple unmodified starting materials through [3+2]‐cycloaddition ([3+2]‐CA) and oxidative aromatization reactions in one pot under amine catalysis. The sequential one‐pot reaction proceeds in good yields with high selectivity by using pyrrolidine as the catalyst from the simple unmodified substrates of enones, aryl azides, and 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). Furthermore, we have demonstrated the medicinal applications of products 4 and 5 through simple organic reactions. Organo‐click approach to benzotriazoles: A practical synthesis of N‐arylbenzotriazoles was achieved through the sequential one‐pot combination of [3+2]‐cycloaddition followed by 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ)‐mediated oxidative aromatization of unmodified cyclic enones with aryl azides. For the first time, the synthesis of privileged CF3 containing N‐arylbenzotriazoles through metal‐free catalysis has been discovered (see scheme).