Cycloaddition reactions of 3,3,3-trifluoropropene derivatives containing an alkoxycarbonyl, sulfonyl, sulfoximine, or sulfamide substituent in position 1 with ethyl isocyanoacetate proceed with the formation of 3-(trifluoromethyl)-2,3-dihydro-1H-pyrroles, whereas their reactions with tosylmethyl isocyanide lead to the formation of 4-(trifluoromethyl)-1H-pyrroles.