Interactions of polyfluoroaromatic imidoyl chloride derivatives with compounds containing nitrogen-carbon multiple bond in the presence of AlCl3 proceed as a cycloaddition type process and lead to five- or six-membered N-containing ring systems. N-(p-R-tetrafluorophenyl)carbonimidoyl dichlorides (R = F, CH3) react with N-pentafluorophenyltrichloroacetimidoyl chloride and AlCl3 to give in good yields 1-(p-R-tetrafluorophenyl)-3-pentafluorophenyl-4,4,5,5-tetrachloro-2-imidazolone. N-Pentafluorophenyltrichloroacetimidoyl chloride "dimerizes" by heating with AlCl3 to 1,3-bis(pentafluorophenyl)-4,5-dichloro-2 This compound was also obtained from 1,3-bis(pentafluorophenyl)-4,4,5,5-tetrachloro-2-imidazolidone under the action of AlCl3. Heating of 1,3-bis(pentafluorophenyl)-4,4,5,5-tetrachloro-2-imidazolidone with AlCl3 in toluene leads to 1,3-bis(pentafluorophenyl)-4,5-dichloro-2-imidazolone and its 5-tolyl derivatives as a result of a reaction with toluene. Interaction of N-pentafluorophenylcarbonimidoyl dichloride with benzonitrile and AlCl3 leads to 1-pentafluorophenyl-4,6-diphenyl-1,3,5-triazine-2-one along with N-pentafluorophenyl-N'-benzoylurea and an N-pentafluorophenylurea complex with benzamide. (C) 2000 Elsevier Science S.A. All rights reserved.