Regioselective Synthesis of 5‐(1,2,3‐Triazol‐1‐yl)isoxazoles by Cyclization of 5‐Azidoisoxazoles with Active Methylene Compounds

Abstract A facile metal‐free approach to 5‐(1,2,3‐triazol‐1‐yl)isoxazoles bearing a variety of functional groups in both heterocyles has been developed. A cyclization of 3‐EWG‐5‐azidoisoxazoles with compounds possessing active methylene group proceeds smoothly under mild conditions in the presence of triethylamine or Cs 2 CO 3 in alcohols or DMF affording fused hybrid triazole‐isoxazole compounds in high yields up to 98%. Some mechanistic aspects of the cyclization reaction are discussed.