Reaction of (Z)-1-aryl-3-hexen-1,5-diynes with sodium azide: synthesis of 1-aryl-1H-benzotriazoles.

[reaction: see text] A novel tandem cascade reaction involving 1,3-dipolar cycloaddition reaction, anionic cyclization, and sigmatropic rearrangement for the synthesis of 1-aryl-1H-benzotriazoles 2 and 3 was accomplished by treatment of the (Z)-1-aryl-3-henen-1,5-diynes (1) with sodium azide in DMF or DMSO at 80 degrees C for 12 h and gives 65-91% yields.