An unusual labilization of a 4‐(trifluoromethyl)thiazole

N ‐Chloro‐4‐(trifluoromethyl)‐5‐thiazolyl‐ N',N' ‐diethylurea 5 has been found to undergo a facile labilization of the trifluoromethyl group under mild conditions. The reaction relies on the assistance of the nitrogen substitution at the 4‐position of the thiazole ring. Treatment of 5 with triethylamine and either methanol or methanethiol replaced the trifluoromethyl group with a methyl ester or a trimethylorthothio ester respectively at room temperature. Combination of 5 with diethylamine led to an unusual thiazolidine with two exocyclic double bonds, 8 .