The reaction of N-(2,2,2-trichloroethylidene)arenesulfonamides with monochloroacetamide involves nucleophilic addition to the C=N bond of the imine function, to give N-(arenesulfonamido-2,2,2-trichloroethyl)chloroacetamides. The latter, in the presence of bases, undergo intramolecular cyclization to give imidazole derivatives.