A simple method for the preparation of di-, tri- and tetrasubstituted non-symmetrical ureas

Article abstract of DOI:10.1055/s-2005-923584

The synthesis of a series of di-, tri- and tetrasubstituted non-symmetrical ureas is described. Di- and trisubstituted ureas are prepared in excellent yield by treatment of a phenyl carbamate in a self-tunable single-mode microwave synthesizer with a primary or secondary amine. The synthetically more challenging tetrasubstituted urea can be prepared using the 4-nitrophenyl carbamate and a secondary amine. Georg Thieme Verlag Stuttgart.