2,2,2-Trifluroenthanol promoted synthesis of unsymmetrical ureas from dioxazolones and amines via tandem lossen rearrangement/condensation process

A 2,2,2-trifluroenthanol (TFE) promoted synthesis of unsymmetric ureas was described. This approach enabled the construction of a variety of ureas from the readily prepared and easy-to-handle dioxazolones and amines via tandem Lossen rearrangement/condensation process. The reaction featured mild conditions for the urea synthesis under metal-free conditions, which was successively applied in the scale-up synthesis of herbicides Monuro and Isoproturon.