A Facile Method for the Preparation of Unsymmetrical Ureas Utilizing Zirconium(IV) Chloride

摘要

A facile synthetic method for the preparation of unsymmetrical ureas from amines is described. Carbamoyl imidazole compounds were prepared by the reaction of 1,1-carbonyldiimidazole with primary or secondary amines, and further activation by treatment with zirconium(IV) chloride to generate the desired urea. This reaction protocol was applied to the synthesis of tri and tetrasubstituted ureas with high yields. This study provides an alternative guideline for the practical preparation of various unsymmetrical ureas.