Synthesis of Quinazolinones by a Friedel-Crafts Heteroannulation Route

Significance

A simple and efficient method for the preparation of 2-alkylaminoquinazolin-4-ones is described. Treatment of anilines with ethoxycarbonyl isothiocyanate gives intermediate guani­dines which, under unusual intramolecular Friedel-Crafts conditions, are transformed into the quinazoline derivatives. The sequence is short and convenient without the need for chromatography since the guanidines may be easily precipitated from water and the end products by trituration with water. The overall yields from the process are high but the substrate scope was inadequately studied.