Microwave-promoted efficient synthesis of dihydroquinazolines

A solvent- and catalyst-free synthesis of dihydroquinazolines is described. 2,4-Disubstituted-1,2-dihydroquinazolines can be readily obtained from 2-aminobenzophenone and aldehydes under microwave irradiation using urea as an environmentally benign source of ammonia, with a small amount of the corresponding quinazolines as the minor product. The reaction is simple, clean and excellent yields are obtained within minutes.