Synthesis and biological activity evaluation of 5-pyrazoline substituted 4-thiazolidinones

Synthesis, X-ray, DFT and photophysical properties of some new ferrocenyl hydrazono thiazolidin-4-ones and their derivatives

Cyclocondensation of thiosemicarbazone of 2-acetylferrocene with α-haloacids and α-haloketones afford new ferrocenyl hydrazono thiazolidin-4-ones and ferrocenyl hydrazono thiazoles respectively. Ferrocenyl hydrazono thiazolidin-4-one is easily converted into enamino ketone with N,N-dimethylformamide dimethyl acetal (DMF-DMA). The compounds were characterized by spectroscopic means and the structure of the new ferrocenyl hydrazono thiazolidin-4-one (3a) was determined by means of X-ray crystallography. The photophysical properties of these compounds were studied by means of UV/visible absorption spectroscopy and fluorescence spectroscopy. Density functional theory (DFT) calculations have been carried out with Gaussian 09W using B3LYP density functional method and 6-31G (d) basis set. (1)H and (13)C Nuclear Magnetic Resonance (NMR) have been calculated and correlated with experimental results. Antimicrobial activity studies of some new compounds have been reported.

An efficient synthesis of new caffeine-based chalcones, pyrazolines and pyrazolo[3,4-b][1,4]diazepines as potential antimalarial, antitrypanosomal and antileishmanial agents

A new series of chalcones 5a-f were synthesized from caffeine-based aldehyde 3 and substituted acetophenones 4a-f. Treatment of compounds 5a-f with hydrazine hydrate led to pyrazolines 6a-f, and their subsequent reaction with acetic anhydride or formic acid afforded the corresponding N-substituted pyrazolines 7a-f and 8a-f respectively. Additionally, the regioselective cyclocondensation reaction of chalcones 5a-f with 4,5-diaminopyrazole 9 afforded the diazepine derivatives 10a-f. Synthesis of the above novel compounds was carried out through a simple procedure involving an easy work-up and mild reaction conditions. In vitro antimalarial activity against Plasmodium falciparum was evaluated for the obtained compounds. Among of them, just pirazoline 6a showed an outstanding growth inhibition percentage 85.2 ± 5.4%, while diazepines 10a-f showed remarkable growth inhibitions in the range of 80.3 ± 13.5 to 94.2 ± 0.2% when were tested at 20 μg/mL. Compounds 5b, 5e, 7c and 7f showed remarkable activities against Leishmania panamensis with growth inhibition of 88.3 ± 1.5, 82.6 ± 2.2, 82.8 ± 1.7 and 87.6 ± 0.5% respectively, at 20 μg/mL. In vitro assays against Trypanozoma cruzi showed that pyrazoline 6d displayed a growth inhibition of 61.9 ± 7.8% at 20 μg/mL while chalcone 5f was considered especially active with a growth inhibition of 9.7 ± 1.5% for a very low concentration of 1.0 μg/mL.

Mannich bases in medicinal chemistry and drug design

The biological activity of Mannich bases, a structurally heterogeneous class of chemical compounds that are generated from various substrates through the introduction of an aminomethyl function by means of the Mannich reaction, is surveyed, with emphasis on the relationship between structure and biological activity. The review covers extensively the literature reports that have disclosed Mannich bases as anticancer and cytotoxic agents, or compounds with potential antibacterial and antifungal activity in the last decade. The most relevant studies on the activity of Mannich bases as antimycobacterial agents, antimalarials, or antiviral candidates have been included as well. The review contains also a thorough coverage of anticonvulsant, anti-inflammatory, analgesic and antioxidant activities of Mannich bases. In addition, several minor biological activities of Mannich bases, such as their ability to regulate blood pressure or inhibit platelet aggregation, their antiparasitic and anti-ulcer effects, as well as their use as agents for the treatment of mental disorders have been presented. The review gives in the end a brief overview of the potential of Mannich bases as inhibitors of various enzymes or ligands for several receptors.

Synthesis, structure prediction, pharmacokinetic properties, molecular docking and antitumor activities of some novel thiazinone derivatives

Convenient synthesis of [1,3]thiazin-4-ones by the unprecedented cyclization of acetylene diesters with 3-alkyl-2,6-diarylpiperidin-4-one thiosemicarbazone derivatives and their antitumor evaluation.

Synthesis and spectral characterization of new homologous 1,3,5-triaryl-2-pyrazolines: Influence of alkyloxy chain length on fluorescence

Twelve new homologous 1,3,5-triaryl-2-pyrazolines (1c-12c) have been synthesized and characterized on the basis of their spectral (IR, (1)H and (13)C NMR and MS) data and microanalysis. The influence of alkyloxy chain length on absorption and fluorescence properties of 1c-12c was studied by UV-Vis and emission spectroscopy. For all the compounds, fluorescence was observed in the blue region of the visible spectrum. Furthermore, a strong influence of alkyloxy chain length was found on the emission intensity of 1,3,5-triaryl-2-pyrazolines, without causing any major blue- or red-shift in the emission wavelength (λmax(em)). The absorption and emission maxima (λmax(abs) and λmax(em)) for all the compounds were observed in the range of 408-416nm and 471-476nm, respectively. The effect of chloro-substituent present on the conjugated backbone of 1,3,5-triaryl-2-pyrazoline moiety is also discussed.

Synthesis and spectral characterization of new 1,3,5-triaryl-2-pyrazolines highlighting effect of alkyloxy chain length on fluorescence

A series of new 1,3,5-triaryl-2-pyrazolines (1b-12b) having one to twelve carbon alkyloxy side chains were synthesized and characterized on the basis of their spectral (IR, (1)H &(13)C NMR and GC-MS) and microanalytical data. The UV-Vis and emission spectroscopy was used to study the effect of alkyloxy chain length on absorption and fluorescence properties of 1b-12b. All the compounds showed fluorescence in the blue region of the visible spectrum. Interestingly, the alkyloxy chain length strongly affects the emission intensity of 1,3,5-triaryl-2-pyrazoline framework without causing any major blue- or red-shift in the emission wavelength (λmax(em)). The absorption and emission maxima (λmax(abs) &λmax(em)) for compounds (1b-12b) were observed in the range of 337-364nm and 454-464nm, respectively. Furthermore, the effect of fluorine substituent on aryl ring present at 3-position of pyrazoline moiety on fluorescence properties is also discussed.

Novel anti-HIV-1 NNRTIs based on a pyrazolo[4,3-d]isoxazole backbone scaffold: design, synthesis and insights into the molecular basis of action

Design and synthesis of novel anti-HIV-1 NNRTIs based on a pyrazolo[4,3-d]isoxazole backbone scaffold.

Efficient pyrrolidine catalyzed cycloaddition of aziridines with isothiocyanates, isoselenocyanates and carbon disulfide “on water”

The cycloaddition of aziridines with isothiocyanates, isoselenocyanates and carbon disulfide is described using pyrrolidine on water. This protocol affords a potential route for the construction of the five membered heterocycles with high yields.

Synthesis, spectral characterization, self-assembly and biological studies of N-acyl-2-pyrazolines bearing long alkoxy side chains

A series of new pyrazoline derivatives (1b-4c) bearing N-acyl arms and nine to twelve carbon long alkoxy side chains was synthesized and characterized on the basis of spectroscopic data and microanalysis. The nature of self-assembly to understand the interplay of alkoxy chain crystallization and various supramolecular interactions was investigated using single crystal X-ray diffraction studies. Interesting self-assembled supramolecular structures of 1b and 4c were observed in the crystal lattice owing to various CH⋯O, H⋯H, CH⋯π, lonepair⋯π and π⋯π interactions. Further, all the synthesized compounds (1b-4c) were screened for their in vitro antifungal and anti-inflammatory activities. Compounds 2b, 3b, 2c and 3c showed significant to moderate antifungal activity against Microsporum canis whereas most of the other compounds were found inactive against all the five tested fungal strains. Good anti-inflammatory activity was observed for compounds 1b with IC50 value 331 μM compared to 273 μM for Indomethacine, a standard reference drug. The bio-activity data demonstrates the relationship between lipophilicity, solubility and bioavailability.