Synthesis of 5‐Substituted 1 H ‐Tetrazoles by the Copper‐Catalyzed [3+2] Cycloaddition of Nitriles and Trimethylsilyl Azide

The copper‐catalyzed [3+2] cycloaddition between various nitriles and trimethylsilyl azide in DMF/MeOH produced the corresponding 5‐substituted 1 H ‐tetrazoles in good to high yields. It was proposed that the reaction proceeds through the formation in situ of a copper azide species and subsequent [3+2] cycloaddition with the nitriles. Furthermore, we found that a copper and triethylamine combined catalyst also promoted the cycloaddition of nitriles and trimethylsilyl azide to afford the 5‐substituted 1 H ‐tetrazoles at relatively low reaction temperatures. The copper azide species would be formed by reaction of the copper catalyst with Et 3 N⋅HN 3 generated in situ.