prop-2-yne 1-iminium triflate salts were generated from 3-trifloxy-3-(trifluoromethyl)prop-2-ene 1iminium salts by triethylamine-assisted elimination of triflic acid and trapped in situ in various cycloaddition reactions. These included Diels-Alder reactions with 1,3-dienes, [2 + 2] cyclo-addition with 1,4-diphenylbuta-1,3-diene, and [3 + 2] cycloaddition with organoazides. All these reactions revealed the excellent dienophilic and dipolarophilic reactivity of the electrophilic C,C triple bond of the novel 3-CF 3 -propyniminium salts.