Ring transformation reactions of 4-hydroxy-3-nitro-6-phenyl-6<i>H</i>-pyrano[3,2-<i>c</i>]quinoline-2,5-dione and antioxidant activity

4-Hydroxy-3-nitro-6-phenyl-6H-pyrano[3,2-c]quinoline-2,5-dione was reacted with some 1,2-binucleophiles, such as hydrazine, phenylhydrazine, and hydroxylamine hydrochloride affording the interesting pyrazolyl and isoxazolylquinolinones. Nucleophilic reactions of 3-nitropyranoquinolinone with different 1,4-binucleophiles, leading to a variety of novel diazepinyl, oxazepinyl, and thiadiazepinylquinolinone derivatives, were described. The structure of compounds was proved by elemental analysis and spectral data. Selected products were screened for their antioxidant activity and showed higher radical scavenging abilities.