A facile synthesis of substituted 3‐amino‐1H‐quinazoline‐2,4‐diones

A new synthesis of a series of 3‐amino‐1H‐quinazoline‐2,4‐diones is described. The 1H‐quinazoline‐2,4‐dione 10 was made starting with fluorobenzoic acid in three high yielding steps. The key step of this synthesis involved the generation of the dianion of urea 7 and the subsequent intramolecular nucleophilic displacement of the 2‐fluoro to form the quinazolinedione ring. The 3‐amino moiety was incorporated using (2,4‐dinitro‐phenyl)‐hydroxylamine as the aminating reagent.