Yury A. Rozin, Johann Leban, Wim Dehaen, Valentine G. Nenajdenko, Vasiliy M. Muzalevskiy, Oleg S. Eltsov, Vasiliy A. Bakulev

1-Trifluoromethyl-substituted 1,3-dicarbonyl compounds are shown to undergo 100% regioselective cyclization in reactions with alkyl and aryl azides to form 4-acyl-5-trifluoromethyl-1,2,3-triazoles. The reaction represents a general method for the synthesis of otherwise difficulty available 4-acyl-5-trifluoromethyl-1,2,3-triazoles. The directing role of the trifluoromethyl group is discussed in the light of stepwise and concerted mechanisms for this reaction.