Quinazolinediones and Quinazolinethiones by Intramolecular Ester Amidation

Abstract

A new synthetic route was devised for synthesis of Quinazoline-2,4(1H,3H)-dione 5 in which salicylic acid 1 was treated with urea 2 to afford urea arylated ortho-urahydroxy benzoic acid 4. Ortho-urahydroxy benzoic acid 4 is the intermediate moiety which upon cyclization corroborated the cyclic formation of 2, 4- quinazolinedione 5. To form the quinazoline derivative 2, 3-dihydro-2- thioxoquinazolin-4(1H)-one 5a thiourea 3 is used in place of urea 2. Thiourahydroxy benzoic acid 4a is another intermediate compound formed by reacting salicylic acid 1 with thiourea 3. Thiourahydroxy benzoic acid 4a upon interamolecular ester amidation gave final product 2, 3- dihydro-2-thioxoquinazolin-4(1H)-one 5a. This new method replaces the isocyanates and cyanides usage for the formation of quinazolinediones because the incorporation of isocyanates and cyanides is extremely poisonous and cause fatal diseases and immediate death upon contact.