Synthesis and antioxidant evaluation of some heterocyclic candidates from 3-(1,3-diphenyl-1<i>H</i>-pyrazol-4-yl)-2-(4-oxo-4<i>H</i>-benzo[<i>d</i>][1,3]oxazin-2-yl)propenonitrile

A new series of quinazoline derivatives bearing a 1,3-diphenylpyrazole core was synthesized starting from 3-(1,3-diphenyl-1<i>H</i>-pyrazol-4-yl)-2-(4-oxo-4<i>H</i>-benzo[<i>d</i>][1,3]oxazin-2yl)propenonitrile <b>(4)</b> through reactions with some nitrogen nucleophiles. Hydrazinolysis of <b>4</b> furnished the biquinazoline and diheterylazine derivatives depending on the reaction conditions. Noteworthy, the benzimidazole derivatives were obtained <i>via</i> treatment with 2-aminoaniline under different reaction conditions. Inspect of the reactions of <b>4</b> with hydrazinecarbothioamide and hydrazinecarbothiohydrazide provided thiosemicarbazide, triazepinoquinazoline, and mercaptotetrazine derivatives. The antioxidant screening disclosed that some of these compounds such as <b>3, 5, 11, 12,</b> and <b>13</b> exhibited significant potency.