Mesoionic compounds with a bridged nitrogen atom. 18. Cyclization of (2-quinazolinylthio)acetic acids

✍ Scribed by K. V. Fedotov; N. N. Romanov

• Book ID: 104781150
• Publisher: Springer US
• Year: 1989
• Tongue: English
• Weight: 430 KB
• Volume: 25
• Category: Article
• ISSN: 0009-3122
• DOI: 10.1007/bf00470029

✦ Synopsis

It was established that mesoionic thiazoloquinazolinium oxides are formed in the action of acetic anhydride on (2-quinazolinylthio)acetic and -phenylacetic acids. The structures of the products were confirmed by their spectral characteristics and chemical transformtions.

We have previously shown [2,3] tht mesoionic thiazolopyrimidinium oxides are formed in the action of acetic anhydride on (2-pyrimidinylthio)acetic and ~-(2-pyrimidinylthio)phenylacetic acids; only one of the possible isomers is obtained in the case of substituted (in the pyrimidine ring) derivatives. The direction of the cyclization is determined not by the electronic nature of the substituent but by steric factors. In order to ascertain the principles of the formation of mesoionic thiazoloazinium oxides it seemed of interest to synthesize the benzo homologs of (2-pyrimidinylthio)acetic acids and investigate their reaction with acetic anhydride. With this end in mind we synthesized (2-quinazolinylthio)acetic (lla-c) and -phenylacetic (Ilia-c) acids on the basis of 2-mercaptoquinazolines la-c [4-6]. R R ~~ scHR' coo~, la-c lla-c, llla-c I--Ili a R=H, b R=CH3,r R=C6H~; II RI=H; III RI=C6tls