Conversion of carbonimidodithioates into unsymmetrical Di- and Tri- substituted ureas including urea dipeptides

Selective hydrolysis of carbonimidodithioates (3) leads to the thiocarbamates (4), which can be easily transformed to the unsymmetrical ureas (5) by treatment with the appropriate amines. This constitutes a synthesis of ureas without the use of phosgene or carbon monoxide.