Synthesis, Identification, and Antioxidant Activity Evaluation of New Diazine 2-Sulfanylbenzoxadiazole Derivatives

Previously unknown 1-(2-{[5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl}acetyl)tetrahydropyridazine-3,6-dione, 1-(2-{[5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl}acetyl)tetrahydropyridazine-1,4-dione, and 2-(2-{[5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl}acetyl)-2,3,5,6,7,8-hexahydrophthalazine-1,4-dione were synthesized by the reaction of 2-{[5-(2-hydroxyphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl}acetohydrazide with succinic, phthalic, and 3,4,5,6-tetrahydrophthalic anhydrides, respectively, in glacial acetic acid. The synthesized compounds were characterized by IR and ¹H and ¹³C NMR spectroscopy, and their potency as antioxidants was evaluated. 1-(2-{[5-(2-Hydroxyphenyl)-1,3,4-oxadiazol-2-yl]sulfanyl}acetyl)tetrahydropyridazine-3,6-dione showed a higher antioxidant activity than the reference antioxidants ascorbic acid that BHT.