New Synthesis of Aryl and Heteroaryl N-Acylureas via Microwave-Assisted Palladium-Catalysed Carbonylation

A new, practical synthesis of aryl and heteroaryl N-acylureas has been developed via palladium-catalysed carbonylation of aryl or heteroaryl halides in the presence of urea nucleophiles. A range of reactions illustrating the wide scope of this reaction was carried out under microwave irradiation, using either carbon monoxide gas in a vessel equipped with a gas inlet adapter, or molybdenum hexacarbonyl as the carbon monoxide source in standard microwave vials. The reactions proceeded in good to excellent yields. To illustrate the usefulness of this method a one-step synthesis of the important insecticide diflubenzuron is reported.