Simple method for the synthesis of 2-trichloromethyl-4-quinazolones

✍ Scribed by M. V. Vovk; L. I. Samarai

• Book ID: 104781737
• Publisher: Springer US
• Year: 1991
• Tongue: English
• Weight: 87 KB
• Volume: 27
• Category: Article
• ISSN: 0009-3122
• DOI: 10.1007/bf00474013

✦ Synopsis

We have previously suggested several approaches to the synthesis of 4-quinazolones I based on the thermolysis of imidazoline-4,5-dione hydrochlorides [1], the reaction of N-arylimino carboxylic acid chlorides with silver cyanate [1], and the phosgenation of N-arylamidines [2].

We have found a new preparatively simple method for the synthesis of 2-trichloromethyl-4-quinazolones Ia-c that proceeds in virtually one step. It consists in the reaction of aromatic amines IIa-c with perchloroethyl isocyanate (III) in the presence of equimolar amounts of 2,4,6-trimethylbenzonitrile oxide (IV). The role of nitrile oxide IV consists in its unique blocking, in the initial stage of the reaction, of the heterocumulene group of isocyanate III [1]; nitrile oxide IV can be recovered in almost quantitative yield after completion of the process. It was established by IR spectroscopy that the reaction actually proceeds through a step involving the previously postulated [2] N-arylimino carboxylic acid isocyanates Va-c (see [3]), which undergo intramolecular cyclization on refluxing in benzene.