An Efficient New Protocol for the Formation of Unsymmetrical Tri- and Tetrasubstituted Ureas.

Abstract A new method for producing unsymmetrical, tetrasubstituted ureas from N, N′-carbonyldiimidazole (CDI) is presented. Carbamoyl imidazolium salts are prepared from the reaction of CDI with a secondary amine, followed by alkylation with MeI. Secondary amines add with ease to imidazolium salts at room temperature to give unsymmetrical, tetrasubstituted ureas in excellent yields.