Synthesis and structure elucidation of kinazoline-thiophene hybrid compounds

The fact that quinazolinone compounds form the active core of pharmacologically important drugs and numerous studies in the literature in this regard have been influential in the creation of this thesis. In this thesis, a total of 17 quinazolin-4(3H)-one derivative compounds, 16 of which are new, were synthesized and structured characterization was performed. In the first step of the thesis, ethyl 2-(thiophen-3-yl)acetimidate hydrochloride compound was synthesized according to Pinner method. The synthesis of 2-(thiophen-3-ylmethyl) quinazoline-4(3H)-one (1) compound, which is the starting material of our synthesis compounds, was carried out as a result of the reaction of the obtained ethyl 2-(thiophen-3-yl)acetimidate hydrochloride compound with 2-aminobenzamide. In the next steps, compound 1 is converted to ethyl 2-(4-oxo-2-(thiophen-3-ylmethyl) quinazolin-3(4H)-yl)acetate (2), and then compound 2 is converted to 2-(4-oxo)-2-thiophen-3-ylmethyl) quinazolin-3(4H)-yl)acetohydrazide (3) with hydrazinehydrate. The corresponding carbothiamide derivatives (4a-e) were synthesized by reacting the compound 3 separately with phenylisothiocyanate, 4-fluorophenylisothiocyanate, 4-methylphenylisothiocyanate, 4-methoxyphenylisothiocyanate, 4-nitrophenylisothiocyanate. Synthesis of 1,3,4-thiadiazole derivatives (5a-e) was carried out as a result of intramolecular cyclization of carbotioamide derivatives (4a-e) in acidic medium, and in the last step, thiazolidinone derivatives (6a-d) were obtained in the presence of carbothiamide derivatives (5a-d), sodiumacetate and ethylbromoacetate. The structural characterization of the synthesized compounds was done by IR, 1H-NMR and 13C-NMR spectroscopic methods. Keywords: Quinazolin-4(3H)-one, 1,3,4-Thiadiazole, Thiazolidinone