SYNTHESIS, CHARACTERIZATION AND PHARMACOLOGICAL EVALUATION OF SOME NOVEL PYRAZOLE AND ISOXAZOLE DERIVATIVES CARRYING 4-CHLORO-3-METHYL PHENOL (P-CHLORO-M-CRESOL) MOIETY
Sushil K. Pagariya* and Pravin S. Bodkhe
ABSTRACT
A new series of 3,5-disubstituted-1-phenyl pyrazoles (6a-d) and 3,5-disubstituted isoxazoles (7a-d) incorporating phenolic moiety of p-chloro-m-cresol viz. 4-chloro-3-methylphenol have been synthesized in excellent yields via interactions of corresponding substituted flavones (5a-d) with phenyl hydrazine hydrochloride and hydroxylamine hydrochloride respectively in DMF solvent with small amount of piperidine. Initially, disubstituted 2-hydroxy acetophenone (2) was prepared by an acetylation of p-chloro-m-cresol followed by Fries rearrangement which on reactions with different aromatic carboxylic acids in dry pyridine using POCl3 gives substituted 2-benzoyloxyacetophenones (3a-d). A Baker-Venkataraman rearrangement (BVT) of substituted 2-benzoyloxyacetophenones (3a-d) with pulverized KOH in dry pyridine gives respective 1,3-diketone or β-diketone derivatives (4a-d) which on dehydrative cyclization in an acidic media yielded required substituted flavones (5a-d) as key intermediate for the synthesis of titled compounds. The structures of newly synthesized pyrazole and isoxazole derivatives have been confirmed by usual chemical characteristics, elemental analysis, IR, 1H NMR and Mass spectroscopic techniques. All the newly synthesized compounds were evaluated in vitro against human pathogenic microorganisms in order to assess their antibacterial and antifungal activities using disc diffusion method. They were also tested for their in vitro antioxidant and anti-inflammatory potential by adopting DPPH free radical scavenging and inhibition of protein denaturation method respectively with reference to standard drugs.
Keywords: Pyrazoles, Isoxazoles, p-Chloro-m-cresol, Synthesis, Pharmacological study.
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