The structure of bicyclic ferrocenylmethylene substituted 2-pyrazolines and their reactions with azodicarboxylic acid N-phenylimide

Polycyclic ferrocenyl(dihydro)thiazepine derivatives: Diastereo-selective synthesis, characterization, electrochemical behavior, theoretical and biological investigation

The reaction of E-2-ferrocenylmethylidenetetralones and E,E-2,6-bis-(ferrocenylmethylidene)-cyclohexanone with 2-aminothiophenol proceed with high diastereoselectivity, forming the ~4.5:1 mixture of trans- and cis-isomers of polycyclic ferrocenylthiazepines, respectively. The reactions of E,E-2,5-bis-(ferrocenylmethylidene)cyclopentanone and E,E-3,5-bis-(ferrocenylmethylidene)-1-methyl-4-piperidone with 2-aminothiophenol take place stereo specifically to form the diastereomeric tricyclic thiazepines of cis- and trans-configuration, respectively. The structures of the obtained compounds were established by IR, ¹H and ¹³C NMR spectroscopy and mass-spectrometry. The structures of the trans-tetralino[1,2a]-, trans-5,7-dimethyltetralino[1,2a]-2-ferrocenyl [1,5]benzo-2,3-dihydrothiazepines and cis-5-ferrocenyl-methylidenecyclopentano[1,2a]-2-ferrocenyl- [1,5]benzo-2,3-dihydrothiazepine were confirmed by X-ray diffraction analysis. An electrochemical study reveals that the diferrocenyl derivatives belong to a Class I compounds of the Robin-Day classification. This behavior is explained by the analysis of frontier orbitals as calculated by density functional theory, showing that only one ferrocenyl unit participates in the generation of HOMO and LUMO orbitals. Compounds 4a and 4c showed similar capacity to inhibit the proliferation of HM1: IMSS trophozoite cultures than the first choice drug for human amoebiasis treatment, metronidazole. Morphological changes induced in the trophozoites after drug exposure suggest a redox in balance as the probable mechanism of the parasite death.

Molecular structure, FT-IR, vibrational assignments, HOMO-LUMO analysis and molecular docking study of 1-[5-(4-Bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 1-[5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone have been investigated experimentally and theoretically using Gaussian09 software package. The title compound was optimized using the HF/6-31G(d) (6D, 7F), B3LYP/6-31G (6D, 7F) and B3LYP/6-311++G(d,p) (5D, 7F) calculations. The B3LYP/6-311++G(d,p) (5D, 7F) results and in agreement with experimental infrared bands. The geometrical parameters are in agreement with XRD data. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. Molecular electrostatic potential was also performed. From the MEP it is evident that the negative charge covers the C=O group and the positive region is over the rings. First hyperpolarizability is calculated in order to find its role in nonlinear optics. Molecular docking studies suggest that the compound might exhibit inhibitory activity against TPII and may act as anti-neoplastic agent.

Structures of the conformational isomers and polymorph modifications of N-substituted 2,6-(E,E)-bis(ferrocenylidene)piperid-4-ones: photo- and electrochemically induced E/Z isomerization

Polymorph modifications for title compounds were investigated.

Synthesis, characterization and antimicrobial studies of new bispyrazolines linked via 3-aryl ring with aliphatic chains

The bispyrazolines 4a(a'-f') and 4b(a'-f') built around the aliphatic chains of varying lengths have been prepared by refluxing bischalcones 3a(a'-f') and 3b(a'-f') with phenyl hydrazine in alcoholic medium. The reactions of chalcones 2a and 2b with suitable 1,ω-dibromoalkanes in the presence of anhydrous K(2)CO(3)/dry acetone and Bu(4)N(+)I(-) (PTC) provided 3a(a'-f') and 3b(a'-f'), respectively. The antibacterial and antifungal activities of the synthesized compounds were evaluated against five bacterial and four fungal strains. The compounds 3ba', 3bc', 3bd', 3be', 3af', 4aa' and 4ba' showed better MIC (μg/mL) against the tested microorganisms.

Eco-friendly synthesis and antimicrobial activities of some 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines

Background

Green catalyst fly ash: H₂SO₄ was prepared by mixing fly ash and sulphuric acid. Microwave irradiations are applied for solid phase cyclization of 5-bromo-2-thienyl chalcones and phenyl hydrazine hydrate in the presence of fly ash: H₂SO₄ yields, 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines. These pyrazolines were characterized by their physical constants and spectral data. The antimicrobial activities of all synthesized pyrazolines have been studied.

Results

Scanning electron microscopy (SEM) analysis shows the morphology changes between fly ash and the catalyst fly ash: H₂SO₄. The SEM photographs with the scale of 1 and 50 μm show the fly-ash particle is corroded by H₂SO₄ (indicated by arrow mark), and this may be due to dissolution of fly ash by H₂SO₄. The yields of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines is more than 75% using this catalyst under microwave heating. All pyrazolines showed moderate activities against antimicrobial strains.

Conclusion

We have developed an efficient catalytic method for synthesis of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines by solid phase cyclization using a solvent-free environmentally greener catalyst fly ash: H₂SO₄ under microwave irradiation between aryl chalcones and hydrazine hydrate. This reaction protocol offers a simple, economical, environment friendly, non-hazardous, easier work-up procedure, and good yields. All synthesized pyrazoline derivatives showed moderate antimicrobial activities against bacterial and fungal strains.

Synthesis and antimicrobial evaluation of some pyrazole derivatives

Reaction of a series of (E)-3-phenyl-4-(p-substituted phenyl)-3-buten-2-ones with p-sulfamylphenyl hydrazine in glacial acetic acid gave the corresponding hydrazones, subsequent treatment of which with 30% HCl afforded pyrazole-1-sulphonamides. On the other hand, refluxing of chalcones with either thiosemicarbazide or isonicotinic acid hydrazide in ethanol containing a few drops of acetic acid gave pyrazoline-1-thiocarboxamides and isonicotinoyl pyrazolines, respectively. The structures of the synthesized compounds were determined on the basis of their elemental analyses and spectroscopic data. The antimicrobial activity of the newly isolated heterocyclic compounds was evaluated against Gram-positive, Gram-negative bacteria and fungi. Most of the compounds showed a moderate degree of potent antimicrobial activity.

3,5-Bis(4-fluoro-phen-yl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde

In the title mol-ecule, C(16)H(12)F(2)N(2)O, the pyrazole ring adopts a slight envelope conformation with the methyl-ene C atom deviating by 0.114 (3) Å from the mean plane of the other four atoms [maximum deviation = 0.021 (3) Å]. The dihedral angles between the four essentially planar atoms of the pyrazole ring and the fluoro-substituted benzene rings are 2.6 (2) and 82.2 (2)°. The dihedral angle between the two benzene rings is 83.7 (2)°. The crystal packing is stabilized by weak inter-molecular C-H⋯O hydrogen bonds.

3,5-Bis(4-fluoro-phen-yl)-1-phenyl-4,5-dihydro-1H-pyrazole

In the title compound, C₂₁H₁₆F₂N₂, the dihedral angle between the fluoro­phenyl groups is 66.34 (8)°, and the dihedral angle between the envelope-configured pyrazole group (N/N/C/C/C) and the benzene ring is 11.50 (9)°. The dihedral angles between the benzene and the two fluoro-substituted phenyl groups are 77.7 (6) and 16.7 (5)°. Weak C—H⋯π interactions contribute to the stability of the crystal structure.

1-[3,5-Bis(4-chloro-phen-yl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone

In the title compound, C₁₇H₁₄Cl₂N₂O, the dihedral angles between the pyrazole ring and the mean planes of the benzene and chloro-substituted benzene rings are 75.97 (1) and 16.63 (1)° respectively. In the crystal, two weak C—H⋯O inter­molecular hydrogen bonds and π–π stacking inter­actions [centroid–centroid distances = 3.774 (4) and 3.716 (7) Å] are observed.

1-[3,5-Bis(4-fluoro-phen-yl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone

In the asymmetric unit of the title compound, C(17)H(14)F(2)N(2)O, there are three independent mol-ecules (A, B and C) which differ slightly in the relative orientations of the two fluoro-phenyl rings. In mol-ecules A and C one of the fluoro-phenyl rings is disordered over two positions, with occupancy ratios of 0.72 (2):0.28 (2) for mol-ecule A and 0.67 (2):0.33 (2) for mol-ecule C. The dihedral angle between the two fluoro-phenyl rings in the independent mol-ecules lie in the range 70.3 (3)-84.0 (3)°. In the crystal structure, the mol-ecules are linked via inter-molecular C-H⋯O and C-H⋯F hydrogen bonds and π⋯π stacking inter-actions [centroid-centroid distance = 3.7508 (13) Å], forming a three-dimensional network.

Synthesis and antibacterial studies of some novel isoxazoline derivatives

A series of 3-[3-(2,4-dichloro-5-fluorophenyl)-5-(2-furyl)-4,5-dihydro-1H-pyrazol- 1-yl]-5-(substituted phenyl/2-thienyl)isoxazolines (4a-j) were prepared. The structures of the isoxazoline derivatives were confirmed on the bases of elemental analysis and spectral data. The compounds were screened for their in vitro antibacterial activity using gram-positive bacteria and gram-negative bacteria.

Microwave-Assisted Synthesis of Some 3,5-Arylated 2-Pyrazolines

Condensation of 2-acetylnaphthalene with benzaldehydes under microwave irradiation affords chalcones which undergo facile and clean cyclizations with hydrazines RNHNH₂ (R= H, Ph, Ac) to afford 3,5-arylated 2-pyrazolines in quantitative yields, also under microwave irradiation and in the presence of dry AcOH as cyclizing agent. The results obtained indicate that, unlike classical heating, microwave irradiation results in higher yields, shorter reaction times (2-12 min.) and cleaner reactions.