Premium
Synthesis of New (Pyrazol‐3‐yl)‐1,3,4‐oxadiazole Derivatives by Unexpected Aromatization During Oxidative Cyclization of 4,5‐Dihydro‐1 H ‐pyrazole‐3‐carbohydrazones and Their Biological Activities
Author(s) -
Jagadeesh Prathap K.,
Himaja M.,
Mali Sunil V.,
Munirajasekhar D.
Publication year - 2014
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.1765
Subject(s) - chemistry , aromatization , pyrazole , carbohydrazide , antioxidant , chloramine t , oxidative phosphorylation , proton nmr , medicinal chemistry , stereochemistry , organic chemistry , biochemistry , catalysis
A series of novel 2‐(4‐(4‐chlorophenyl)‐1 H ‐pyrazol‐3‐yl)‐5‐(Aryl)‐1,3,4‐oxadiazoles were synthesized by unexpected aromatization during oxidative cyclization of 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1 H ‐pyrazole‐3‐carbohydrazones using chloramine‐T as an oxidant. The hydrazones were derived from 4‐(4‐chlorophenyl)‐4,5‐dihydro‐1 H ‐pyrazole‐3‐carbohydrazide and various substituted aldehydes. The structure of the synthesized compounds was confirmed by FTIR, 1 H NMR, 13 C 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.