The novel cyclization/fluorination reaction of N-dienes in superacid was extended to substituted substrates. The influence of the substitution on superelectrophilic character of dicationic intermediates was shown and its dramatic effect on the synthesis of fluoropiperidines was studied. On the basis of new dicationic alpha-chloronium ammonium intermediates, starting from halogen-substituted dienes, high-valued fluorinated piperidines were synthesized.