Synthesis and antidepressant activity of some 1,3,5-triphenyl-2-pyrazolines and 3-(2″-hydroxy naphthalen-1″-yl)-1,5-diphenyl-2-pyrazolines

Cinchona alkaloid catalyzed enantioselective amination of α,β-unsaturated ketones: an asymmetric approach to Δ2-pyrazolines

Δ²-Pyrazolines are of significant medicinal and synthetic interest due to their therapeutic properties and utility in the synthesis of 1,3-diamines, yet few asymmetric methods exist to prepare them. An unprecedented highly enantioselective organocatalytic synthesis of 2-pyrazolines was achieved through an asymmetric conjugate addition catalyzed by 9-epi-amino cinchona alkaloids followed by deprotection-cyclization, which furnished chiral 2-pyrazolines in 46-78% yield and 59-91% ee. This bifunctional catalytic methodology thus provides easy access to considerable range of optically active 3,5-dialkyl 2-pyrazolines.

Gold(I)-catalyzed formation of 3-pyrazolines through cycloaddition of diaziridine to alkynes

This work reports the high-yield formation of pyrazoline derivatives mediated by gold(I) catalysts. The reaction utilizes a diaziridine, which has seen only limited usage in organic methodology. Mechanistic studies suggest a gold-mediated opening of the diazridine ring, alkyne insertion, and finally an intramolecular hydroamination to furnish the product.

Synthesis and in vitro antimicrobial activity of some pyrazolyl-1-carboxamide derivatives

A series of 3,5-disubstituted pyrazole-1-carboxamides were obtained by treatment of chalcones with semicarbazide hydrochloride in dioxane containing sodium acetate/acetic acid as a buffer solution. N-acetyl derivatives of pyrazole-1-carboxamides were isolated in good yields either by treatment of the carboxamide derivatives with acetic anhydride or refluxing chalcones with semicarbazide in ethanol containing few drops of acetic acid to give the corresponding hydrazones. Subsequent treatment of hydrazones with acetic anhydride gave the desired N-acetyl pyrazole-1-carboxamides derivatives. When chalcones were refluxed with dioxane containing few drops of acetic acid, 4,5-dihydropyrazole-1-carboxamides were isolated, which were subsequently oxidized using 5% sodium hypochlorite in dioxane to afford pyrazole-1-carboxamides. The structures of isolated compounds were confirmed by elemental analyses and spectral methods. The isolated compounds were tested for their antimicrobial activities.

2-[5-(4-Meth-oxy-phen-yl)-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl]-6-methyl-1,3-benzothia-zole

In the title compound, C(24)H(21)N(3)OS, the pyrazole ring makes dihedral angles of 5.40 (7) and 6.72 (8)° with the benzo[d]thiazole ring system and the benzene ring, respectively, and a dihedral angle of 85.72 (8)° with the meth-oxy-substituted benzene ring. In the crystal structure, the mol-ecules are linked by C-H⋯π inter-actions.

Synthesis and biological evaluation of some 4-functionalized-pyrazoles as antimicrobial agents

1,3-Diaryl-4-formylpyrazoles 8 bearing benzenesulfonamide moiety at position-1 were synthesized as important intermediates following Vilsmeier-Haack strategy. Aldehyde moiety of 4-formylpyrazole was then converted into carboxylic acid 9, cyano 10 and carbothioamide 11 using established procedures. Out of these 4-functionalized pyrazoles, pyrazole-4-carboxylic acids 9 and carbothioamides 11 were evaluated for their in vitro antibacterial activity against four pathogenic bacterial strains namely, Staphylococcus aureus, Bacillus subtilis (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative), and in vitro antifungal activity against two pathogenic fungal strains namely, Aspergillus niger and Aspergillus flavus. Three tested compounds, 9e, 11b and 11f exhibited moderate antibacterial activity against Gram-positive bacteria and 9g showed moderate antifungal activity against the tested fungi. However, none of the compounds showed any activity against Gram-negative bacteria.

'One-pot' ultrasound irradiation promoted synthesis and spectral characterization of an array of novel 1,1'-(5,5'-(1,4-phenylene)bis(3-aryl-1H-pyrazole-5,1(4H,5H)-diyl))diethanones, a bis acetylated pyrazoles derivatives

An array of novel 1,1'-(5,5'-(1,4-phenylene)bis(3-aryl-1H-pyrazole-5,1(4H,5H)-diyl))diethanones, a bis acetylated pyrazoles derivatives are synthesized in 'one-pot' by ultrasound irradiation method and are characterized by melting point, elemental analysis, MS, FT-IR, one-dimensional NMR (1H and 13C) and two-dimensional NOESY spectra. The methylene and methane protons of pyrazoles moiety splits signal as ABX pattern in the proton NMR spectra and the key nOe correlations are confirmed by NOESY spectrum.

Synthesis and Antimicrobial Studies of Tridentate Schiff Base Ligands with Pyrazolone Moiety and Their Metal Complexes

Synthesis, characterization, and antimicrobial activity of tridentate Schiffbase ligands containing pyrazolone moiety (3a and 3b) and their transition metal complexes of VO(II), Cu(II), Fe(III), and Co(II) 4a–h have been investigated. The complexes show enhanced antibacterial activity against S. aureus, E. coli, and S. typhi and antifungal activity against C. albicans, Rhizopus sp., and A. niger compared to the ligands.

Synthesis of 1-(4-methoxybenzyl)-3-cyclopropyl-1H-pyrazol-5-amine derivatives as antimicrobial agents

A series of novel substituted 1-(4-methoxybenzyl)-3-cyclopropyl-1H-pyrazol-5-amine benzamides 9(a-h) were synthesized to determine their antibacterial and antifungal activities as well as possible structure-activity relationships (SARs) to improve therapeutic efficacy. The pyrazol-5-amine benzamides were screened for their antibacterial activity against standard strains of Gram-positive (Streptococcus pyogenes NCIM 2608, Staphylococcus aureus ATCC 29737, Bacillus subtilis NCIM 2010) and Gram-negative (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 20852, Klebsiella pneumoniae MTCC 618) bacteria by using streptomycin as positive control. They were also tested for their antifungal activities against mycotoxic strains of Fusarium verticillioides, Aspergillus ochraceous, Aspergillus flavus, Alternaria alternata, and Penicillium chrysogenum using nystatin as positive control. Among the synthesized compounds, 9d, 9g, and 9h showed potent antimicrobial activities.

Development of selective and reversible pyrazoline based MAO-A inhibitors: Synthesis, biological evaluation and docking studies

3,5-Diaryl pyrazolines analogs were synthesized and evaluated for their monoamine oxidase (MAO) inhibitory activity. The compounds were found reversible and selective towards MAO-A with selectivity index in the magnitude of 10(3)-10(5). The docking studies were carried out to gain further structural insights of the binding mode and possible interactions with the active site of MAO-A. Interestingly, the theoretical (K(i)) values obtained by molecular docking studies were in congruence with their experimental (K(i)) values.

An improved procedure for synthesis of some new 1,3-diaryl-2-propen-1-ones using PEG-400 as a recyclable solvent and their antimicrobial evaluation

A simple and convenient route is described for the synthesis of novel hetero 1,3-diaryl-2-propen-1-ones (chalcones) by using recyclable PEG-400 as an alternative reaction solvent. The reaction is clean with excellent yield, shorter reaction time and reduces the use of volatile organic compounds (VOCs). All the synthesized compounds were evaluated for their antimicrobial activities against several pathogenic representatives.

Synthesis of some new S-triazine based chalcones and their derivatives as potent antimicrobial agents

Base catalysed condensation of ketone 5 with different aldehydes give chalcones, 2.4-bis-(phenylamino)-6-[4'-{3''-(4'''-substituted phenyl/2'''-furanyl/2'''-thienyl)-2''-propenon-1''-yl}phenylamino]-s-thriazines 6a-e. These chalcones on cyclization with hydrazine hydrate in the presence of glacial acetic acid, guanidine nitrate in the presence of alkali and malononitrile in the presence of ammonium acetate give the corresponding acetylpyrazolines 7a-e, aminopyrimidines 8a-e and cyanopyridines 9a-e respectively. The products 6a-e, 7a-e, 8a-e and 9a-e were fully characterized by spectroscopic and elemental analysis and also tested for antibacterial activity.

Synthesis and characterization of a series of 1,3,5-trisubstituted-2-pyrazolines derivatives using methanoic acid under thermal condition

An efficient and practical synthesis of 1,3,5-trisubstituted 2-pyrazoline structures was achieved through cyclization of phenylhydrazine with ?,? -unsaturated ketones (chalcones) using methanoic acid (formic acid) as catalyst under thermal condition.