Paper
Synthesis of New (Pyrazol-3-yl)-1,3,4-oxadiazole Derivatives by Unexpected Aromatization During Oxidative Cyclization of 4,5-Dihydro-1H-pyrazole-3-carbohydrazones and Their Biological Activities
Published May 1, 2014 · K. Prathap, M. Himaja, Sunil V. Mali
Journal of Heterocyclic Chemistry
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Abstract
A series of novel 2-(4-(4-chlorophenyl)-1H-pyrazol-3-yl)-5-(Aryl)-1,3,4-oxadiazoles were synthesized by unexpected aromatization during oxidative cyclization of 4-(4-chlorophenyl)-4,5-dihydro-1H-pyrazole-3-carbohydrazones using chloramine-T as an oxidant. The hydrazones were derived from 4-(4-chlorophenyl)-4,5-dihydro-1H-pyrazole-3-carbohydrazide and various substituted aldehydes. The structure of the synthesized compounds was confirmed by FTIR, 1H NMR, 13C NMR, and mass spectral data. The synthesized compounds were evaluated for their antitubercular and antioxidant activities. All the compounds 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h and 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h showed good antitubercular activity against Mycobacterium tuberculosis (minimum inhibitory concentration = 25 µg/mL for 4f and 4g, 50–100 µg/mL for the rest). However, all the compounds exhibited poor antioxidant activity against 1,1-diphenyl-2-picryl-hydrazil free radical.
Novel 2,4-(4-chlorophenyl)-1H-pyrazol-3-yl)-5-(Aryl)-1,3,4-oxadiazole derivatives show good antitubercular activity against Mycobacterium tuberculosis, but poor antioxidant activity against 1,1-
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