Categories: Synthesis of N-Heterocycles > Synthesis of pyrazoles

Pyrazole is an organic compound with the formula C 3 H 3 N 2 H

Buchwald phosphine ligands for C-C, C-N, and C-O bond formation.

The synthesis of a novel of pyrazole derivatives was achieved by condensation of acetyl furan with phenyl hydrazine to give hydrazone (1) On the other hand, cyclization of α, β-unsaturated ketone. Using Vilsmeier reagent by DMF (dimethylformamid) and POCl3 Phosphorusoxychloride) to give compound (2). The chemical structures of allnew compounds were established by IR, ¹HNMR, and mass spectra data. All the synthesized compounds were screened for in vitro antibacterial activity and most of them showed potency against both gram positive and gram negative bacteria. Compounds 4-(α-benzoyl aminoacrylic acid) – 3 – Furayl-1-phenylpyrazol, 4 – (α-benzoylaminomethylacrylate)-3-Furayl-1-phenylpyrazol, 4- (2-4-dinitrophenylhydrazone)-3-Furayl-1-phenylpyrazole showed the highest antibacterial activity against Bacillus subtilis strain with minium inhibition zone 19 mm.

The synthesis of a novel of pyrazole derivatives was achieved by condensation of acetyl furan with phenyl hydrazine to ..

PDF Downloads : Oriental Journal of Chemistry

Pyrazole-3-one compounds were designed on the basis of docking studies of previously reported antidiabetic pyrazole compounds. The amino acid residues found during docking studies were used as guidelines for the modification of aromatic substitutions on pyrazole-3-one structure. Depending on the docking score, the designed compounds were selectively prioritized for synthesis. The synthesized compounds were subjected to in vivo hypoglycemic activity using alloxan induced diabetic rats and metformin as a standard. Compound 4 having sulphonamide derivative was found to be the most potent compound among the series.

In light of the above, a new series of aryl substituted pyrazole-3-one derivatives were synthesized and evaluated for their possible hypoglycaemic activity. Substituted phenylhydrazines were prepared from anilines by diazotization. Pyrazole-3-one-4-carboxylate derivatives were then generated by reacting diethylethoxymethylene malonate (DEEM) with substituted phenyl hydrazine through base catalyzed cyclization reaction. The compounds were synthesized by Michael addition reaction, which is a nucleophilic addition of enolate anions to the carbon-carbon double bond of α,β-unsaturated carboxylic acid derivatives. The synthesized compounds were tested for hypoglycaemic activity.

10 posts published by DR ANTHONY MELVIN CRASTO Ph.D during May 2017

Activated enol ethers 3 derived from trialkyl orthoformate and active methylidene compounds such as diesters, dinitriles of malonic acid or pentane-2,4-dione are excellent three-carbon synthons. They act as trifunctional electrophiles for the syntheses of tautomeric pyrazoles when reacted with hydrazine thereby obtaining 3,4-disubstituted pyrazoles, namely 3-amino-1H-pyrazole-4-carbonitrile (5a), alkyl 3-hydroxypyrazole-4-carboxylates 5b, 5c or 1-(3-methyl-1H-pyrazol-4-yl)ethanone (5d). The reversed addition of the enol ethers to hydrazine hydrate the formation of bis-enehydrazine 6 product was observed in two tautomeric forms: with symmetrical and unsymmetrical structures of the ethylene substituent. This structure has been established by X-ray analysis. The tautomeric behavior of these materials has been modelled by using DFT quantum-chemical calculations. The most stable structural forms are 5aA1, 5aA2, 5bE1, 5bE2, 5cE1, 5cE2, 5dA1 and 5dA2.