Concise and Additive‐Free Click Reactions between Amines and CF3SO3CF3

Abstract Trifluoromethyl trifluoromethanesulfonate has proved to be an excellent reservoir of difluorophosgene and a promising click ligation for amines in the preparation of urea derivatives, heterocycles, and carbamoyl fluorides under metal‐ and additive‐free conditions. The reactions are rapid, efficient, selective, and versatile, and can be performed in benign solvents, giving products in excellent yields with minimal efforts for purification. The characteristics of the reactions meet the requirements of a click reaction. The use of trifluoromethyl trifluoromethanesulfonate as a click reagent is advantageous over other “CO” sources (e.g., TsOCF 3 , PhCO 2 CF 3 , CsOCF 3 , AgOCF 3 , and triphosgene) because this reagent is readily accessible; easy to scale up; and highly reactive, even under metal‐ and additive‐free conditions. It is anticipated that CF 3 SO 3 CF 3 will be increasingly as important as SO 2 F 2 as a click agent in future drug design and development.