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Short Paper | Regular issue | Vol 83, No. 2, 2011, pp.339-349
Published online, 1st December, 2010
DOI: 10.3987/COM-10-12093
Synthesis and Reactions of a New Series of 1,2,4-Triazolo[4,3-c]quinazolines

Kamal F. M. Atta,* Mohamed G. Marei, and Fatma A. M. Mohamed

*Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, Ibrahimia, Alexandria 21321, Egypt

Abstract

3-Ethoxycabonyl-1,2,4-triazolo[4,3-c]quinazoline (2) has been synthesized in excellent yield by the condensation of 4-hydrazinoquinazoline (1) with diethyl oxalate and was converted into 3-carbohydrazide 3. The later product was treated with potassium thiocyanate, phenylisothiocyanate or carbon disulfide followed by reaction with hydrazine hydrate to give the respective new 1,2,4-triazolo[4,3-c]quinazoline derivatives 4, 8 or 12. Dehydrative cyclization of the later compounds with concentrated sulphuric acid, sodium hydroxide, m-bromobenzoic acid, carbon disulfide, oxalic acid, phenacyl bromide or benzoin yielded the target heterocycles namely, 1,3,4-thiadiazole, 1,2,4-triazole, 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole or 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazine incorporating 1,2,4-triazolo[4,3-c]quinazoline ring. The structure of the above compounds was confirmed from their spectral characteristics.