Highly Efficient Synthesis of New 3,5-Substituted (Isoxazolines) and 2,3,5-Trisubstituted (Pyrazolines) Mediated by Chloramin-T and Their Evaluation of Antioxidant and Antibacterial Activities

Abstract: Two short series of five membered heterocyclic 3,5-disubstituted–isoxazolines derivatives (Va–f) and 2,3,5-trisubstituted-pyrazolines derivatives (VIIa–f) were synthesized via 1,3-dipolar cycloaddition reaction of 2-(allyloxy)-4,6-dimethoxypyrimidine (III) with aromatic aldoximes (IV) which undergo oxidative–dehydrogenation with Chloramine-T to give 3,5-disubstituted–isoxazolines derivatives (Va–f) and oxidative cyclization of diphenyl hydrazones (VI) using Chloramine-T to give 2,3,5-trisubstituted-pyrazoline derivatives (VIIa–f) in good yield. The newly synthesized compounds were screened for anti-oxidant and anti-microbial activities. 2,3,5-trisubstituted-pyrazolines derivatives (VIIb–e) revealed higher antioxidant activity at 10 µg/mL while 3,5-disubstituted-isoxazolines derivatives (Va–c) and 2,3,5-trisubstituted-pyrazolines derivatives (VIIa–c) showed better anti-microbial activity at 100 µg/mL compared with standard vitamin C and ciprofloxacin, respectively. Structures of newly synthesized compounds were established on the basis of their elemental analysis and spectral IR, ¹H-NMR and ¹³C-NMR.