1-Trifluoromethyl-prop-2-yne 1-iminium salts and 1-imines: reactions with the mesoionic Nitron

The heterocyclic mesoionic compound (1,4- diphenyl-1H-1, 2,4-triazol-4-ium-3-yl)(phenyl)amide (Nitron) has recently been found to exist in a prototropic equilibrium with minor amounts of a nucleophilic heterocyclic carbene of the 1,2,4-triazolyl-5-ylidene type. Here we report that Nitron reacts with 1-trifluoromethyl-substituted prop-2-yne iminium salts by conjugate nucleophilic addition of the anionic PhN- substituent in the mesoionic tautomer, whereas the nucleophilic triazolylidene form is involved in the reaction with 1-CF3-prop-2-yne imines. 3-(2,3-Dihydro-1H-benzo[c]azepin-5-yl)-1H-1,2,4-triazol-4-ium triflate salts were obtained in the former case and (Z)-9-arylidene-1,2,4,7-tetraazaspiro [4,4]nona-2,7-dienes in the latter.