Copper-Catalyzed Cascade Cyclization Reaction of 2-Haloaryltriazenes and Sodium Azide: Selective Synthesis of 2 H-Benzotriazoles in Water

A new approach to the synthesis of 2 H‐benzotriazoles is described. This strategy is based on the copper‐catalyzed CN coupling of 2‐haloaryltriazenes or 2‐haloazo compounds with sodium azide and the intramolecular addition of nitrene to NN bonds. This approach allows the synthesis of various N‐amino‐ and N‐aryl‐2 H‐benzotriazoles in water, in good to excellent yields. The procedure is simple and the starting materials and catalyst are easily available, offering a practical and convenient synthetic route to 2‐substituted benzotriazoles. A new approach to the synthesis of 2 H‐benzotriazoles is described. This strategy is based on the copper‐catalyzed CN coupling of 2‐haloaryltriazenes or 2‐haloazo compounds with sodium azide and the intramolecular addition of a nitrene species to NN bonds (see scheme; TMEDA=N,N,N′,N′‐tetramethylethylenediamine; CTAB=hexadecyltrimethylammonium bromide). This approach allows the synthesis of various N‐amino‐ and N‐aryl‐2 H‐benzotriazoles in water, in good to excellent yields.