Reactions of 1,2,3-Triazoles with Trifluoromethanesulfonyl Chloride and Trifluoromethanesulfonic Anhydride

Reactions of 4,5-dibromo-1,2,3-triazole, 1H-1,2,3-benzotriazole, and 2-phenyl-2H-1,2,3-triazole-4-carbonyl chloride with trifluoromethanesulfonyl chloride and trifluoromethanesulfonic anhydride were studied. 4,5-Dibromo-1,2,3-triazole sodium salt reacted with CF₃SO₂Cl in tetrahydrofuran to give 4,5-dibromo-2-(2-tetrahydrofuryl)-2H-1,2,3-triazole rather than expected 4,5-dibromo-2-trifluoromethylsulfonyl-2H-1,2,3-triazole. The latter was synthesized by treatment of 4,5-dibromo-1,2,3-triazole sodium salt with trifluoromethanesulfonic anhydride. The reaction of benzotriazole with (CF₃SO₂)₂O afforded 1-trifluoromethylsulfonyl-1H-1,2,3-benzotriazole and 1,2,3-benzotriazolium trifluoromethanesulfonate. 2-Phenyl-2H-1,2,3-triazole-4-carbonyl chloride reacted with trifluoromethanesulfonamide sodium salt in DMF, yielding N-(dimethylaminomethylene)trifluoromethanesulfonamide. Possible ways for formation of the unexpected products were proposed.