Synthesis and antioxidant evaluation of some heterocyclic candidates from 3-(1,3-diphenyl-1H-pyrazol-4-yl)-2-(4-oxo-4H-benzo[d][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-1H-pyrazol-4-yl)-2-(4-oxo-4H-benzo[d][1,3]oxazin-2yl)propenonitrile (4) through reactions with some nitrogen nucleophiles. Hydrazinolysis of 4 furnished the biquinazoline and diheterylazine derivatives depending on the reaction conditions. Noteworthy, the benzimidazole derivatives were obtained via treatment with 2-aminoaniline under different reaction conditions. Inspect of the reactions of 4 with hydrazinecarbothioamide and hydrazinecarbothiohydrazide provided thiosemicarbazide, triazepinoquinazoline, and mercaptotetrazine derivatives. The antioxidant screening disclosed that some of these compounds such as 3, 5, 11, 12, and 13 exhibited significant potency.