Synthesis and in vitro antifungal evaluation of 1,3,5-trisubstituted-2-pyrazoline derivatives

Diverse Pharmacological Potential of different Substituted Pyrazole Derivatives

The chemistry of heterocyclic compounds has been a topic of research interest. Some five-membered heterocyclic compounds have been the subject of extensive research due to their different types of pharmacological effects. The five-membered nitrogen-containing heterocyclic compounds pyrazole, pyrazoline, and pyrazolone derivatives have a lot of interest in the fields of medical and agricultural chemistry due to their diverse spectrum of therapeutic activities. Various substituted pyrazole, pyrazoline, and pyrazolone compounds exhibited diverse pharmacological effects like Anti-microbial, anti-inflammatory, anti-tubercular, anti-fungal, anti-malarial, anti-diabetic, diuretic, anti-depressant, anticonvulsant, antioxidant, anti-leishmanial, antidiabetic, and antiviral, etc. In recent decades, the synthesis of numerous pyrazole, pyrazoline, and pyrazolone derivatives by different synthetic methods as well as research into their chemical and biological behavior have become more important. This review focuses on synthetic methods of the pyrazole, pyrazoline, and pyrazolone derivatives, which have significant biological properties and a variety of applications.

Synthesis and Biological Activity Evaluation of Novel Chalcone Analogues Containing a Methylxanthine Moiety and Their N-Acyl Pyrazoline Derivatives

On the basis of the structures of natural methylxanthines and chalcone, a series of novel chalcone analogues containing a methylxanthine moiety, Ia-Ig, and their N-acyl pyrazoline derivatives IIa-IIz and IIaa-IIaf were synthesized and identified through melting points, 1H NMR, 13C NMR, and HRMS. The single crystal of compound IId was obtained, which further illustrated the structural characteristics of the methylxanthine-acylpyrazoline compounds. The biological tests showed that some of them displayed favorable insecticidal activities toward Plutella xylostella L. and were superior to the natural methylxanthine compound caffeine while being comparable with the insecticide triflumuron (e.g., compound Ic: LC50 = 16.8508 mg/L, IIf: LC50 = 1.5721 mg/L, against P. xylostella). Of these compounds, Ic, IIf, and IIu could serve as novel insecticidal leading structures for further study. Some of the compounds showed good fungicidal activities (e.g., compound Ig: EC50 = 14.74 μg/mL, against Rhizoctonia cerealis; IIf: EC50 = 7.06 μg/mL, against Physalospora piricola; IIac: EC50 = 5.37 and 8.19 μg/mL, against Phytophthora capsici and Sclerotinia sclerotiorum, respectively); Ic, Ig, IIa, IIf, IIr, IIs, IIv, IIac, and IIaf could be novel fungicidal leading compounds for further exploration. Furthermore, most of the tested compounds exhibited apparent herbicidal activities against Brassica campestris at a concentration of 100 μg/mL; among others, compound IIa was the best one both toward Brassica campestris and Echinochloa crusgalli and deserves further investigation. The structure-activity relationships of these compounds were also summarized and discussed in detail. The contrast experiment results of compounds C-1 and C-2 showed a positive effect on the biological activity enhancement from the combination of the methylxanthine moiety with the N-dichloroacetyl phenylpyrazoline skeleton. In addition, two 3D-QSAR models with predictive capability were constructed based on the insecticidal and fungicidal activities to afford deep insight into the bioactivity profiles of these compounds. This research provides useful guidance and reference for the discovery and development of novel xanthine natural product-based pesticides.

PEG-mediated synthesis, antibacterial, antifungal and antioxidant studies of some new 1,3,5-trisubstituted 2-pyrazolines

A new series of 1,3,5-trisubstituted 2-pyrazoline derivatives (3a-l) are synthesized in good to excellent yields from the corresponding chalcones (1a-h) and acid hydrazides (2a-e) in polyethylene glycol-400 (PEG-400) as a green reaction medium. The newly synthesized 2-pyrazoline derivatives are screened for their antibacterial and antifungal activity. The synthesized trisubstituted pyrazolines displayed moderate to good antibacterial and antifungal properties as compared with the standard reference penicillin and fluconazole drugs. Additionally, the antioxidant potential of the 1,3,5-trisubstituted 2-pyrazolines is evaluated by OH and DPPH assay. The 1,3,5-trisubstituted 2-pyrazolines showed good radical scavenger activity and were found as good antioxidant agents.

One-pot synthesis, molecular docking, ADMET, and DFT studies of novel pyrazolines as promising SARS-CoV-2 main protease inhibitors

Pyrazoline and its derivatives have numerous prominent pharmacological effects. Focusing on its anti-viral property, we have designed and synthesized three novel pyrazoline derivatives (A1–A3) through one-pot three components and characterized them using different spectroscopic techniques (FT-IR, ¹H NMR, ¹³C NMR, and UV). These compounds were evaluated against SARS-CoV-2 main protease utilizing in-silico molecular docking studies. The docking results displayed good inhibitory activity of the synthesized compounds. Among them, compound A2 was the most active against targeted protein. The drug-likeness and ADMET properties were predicted to have varied profiles but could still be developed, especially A2. DFT/TD-DFT calculations through B3LYP/6-311G++ level of theory were applied to provide comparable theoretical data along with MEP map and electronic energy gap of HOMO → LUMO.

Synthesis of 2-Pyrazolines with a CF3- and Alkyne-Substituted Quaternary Carbon Center via [3 + 2] Cycloaddition of β-CF3-1,3-enynes and Diazoacetates

Given the importance of both the CF₃ group and the alkyne moiety in synthetic/medicinal chemistry, we report here the first example of efficient synthesis of 2-pyrazolines with a CF₃- and alkyne-substituted quaternary carbon center. This methodology has the advantages of high functional group compatibility, the avoidance of base and open-flask conditions, easily available and easy to handle reagent, and broad substrate scope. Notably, this protocol allows for the late-stage functionalization of biologically active molecules and the gram-scale synthesis.

Designing, synthesis and bioactivities of 4-[3-(4-hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamides

In this study, 4-[3-(4-hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide (1-9) types compounds were synthesized and their chemical structures were confirmed by 1H NMR, 13C NMR and HRMS spectra. Cytotoxic and carbonic anhydrase (CA) inhibitory effects of the compounds were investigated. Cytotoxicity experiments pointed out that compound 4, (4-[5-(4-chlorophenyl)-3-(4-hydroxyphenyl)-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide), exerting the highest tumor selectivity (TS) and potency selectivity expression (PSE) values, can be considered as a lead compound of this study in terms of development of novel anticancer agents. All synthesized sulfonamides showed a good inhibition profile on hCA IX and XII in the range of 53.5-923 nM and 6.2-95 nM, respectively. These compounds were 2.5-13.4 times more selective for the inhibition of hCA XII versus hCA IX, except compound 2 which had similar inhibitory action towards both isoenzymes.

Antitumor potential of 1-thiocarbamoyl-3,5-diaryl-4,5-dihydro-1H-pyrazoles in human bladder cancer cells

Bladder cancer is a genitourinary malignant disease common worldwide. Current chemotherapy is often limited mainly due to toxicity and drug resistance. Thus, there is a continued need to discover new therapies. Recently evidences shows that pyrazoline derivatives are promising antitumor agents in many types of cancers, but there are no studies with bladder cancer. In order to find potent and novel chemotherapy drugs for bladder cancer, a series of pyrazoline derivatives 2a-2d were tested for their antitumor activity in two human bladder cancer cell lines 5647 and T24. The MTT assay showed that the compounds 1-thiocarbamoyl-3,5-diphenyl-4,5-dihydro-1H-pyrazole (2a) and 1-thiocarbamoyl-5-(4-chlorophenyl)-3-phenyl-4,5-dihydro-1H-pyrazole (2c) decrease the cell viability of 5637 cells. Molecular modeling indicated that these compounds had a good oral bioavailability and low toxicities. Clonogenic assay and flow cytometric analysis were used to assess colony formation, apoptosis induction and cell cycle distribution. Overall, our results suggest that pyrazoline 2a and 2c, with the substituents hydrogen and chlorine respectively, may decrease cell viability and colony formation of bladder cancer 5637 cell line by inhibition of cell cycle progression, and for pyrazoline 2a, by induction of apoptosis. As indicated by the physicochemical properties of these compounds, the steric factor influences the activity. Therefore, these pyrazoline derivatives can be considered promising anticancer agents for the treatment of bladder cancer.

Alkyne Cycloadditions Mediated by Tetrabutylammonium Fluoride: A Unified and Diversifiable Route to Isoxazolines and Pyrazolines

A versatile approach to isoxazolines and pyrazolines by the cyclization of alkyne substrates using tetrabutylammonium fluoride (TBAF) is described. The reported diheteroatom cycles were produced under mild reaction conditions and with broad product scope. Evidence is also provided for a vinyl anion intermediate produced under unusually mild conditions, which was trapped in situ as part of a tandem cyclization/aldehyde addition sequence. Finally, a deprotection/functionalization method is described, leading to a substituted pyrazoline in good diastereoselectivity.

Microwave-assisted synthesis and bioevaluation of new sulfonamides

In this study, 4-[5-(4-hydroxyphenyl)-3-aryl-4,5-dihydro-1H-pyrazol-1-yl]benzenesulfonamide derivatives (8-14) were synthesized for the first time by microwave irradiation and their chemical structures were confirmed by ¹H NMR, ¹³C NMR and HRMS. Cytotoxic activities and inhibitory effects on carbonic anhydrase I and II isoenzymes of the compounds were investigated. The compounds 9 (PSE = 4.2), 12 (PSE = 4.1) and 13 (PSE = 3.9) with the highest potency selectivity expression (PSE) values in cytotoxicity experiments and the compounds 13 (Ki = 3.73 ± 0.91 nM toward hCA I) and 14 (Ki = 3.85 ± 0.57 nM toward hCA II) with the lowest Ki values in CA inhibition studies can be considered as leader compounds for further studies.

Crystal structures of (5RS)-(Z)-4-[5-(furan-2-yl)-3-phenyl-4,5-di-hydro-1H-pyrazol-1-yl]-4-oxobut-2-enoic acid and (5RS)-(Z)-4-[5-(furan-2-yl)-3-(thio-phen-2-yl)-4,5-di-hydro-1H-pyrazol-1-yl]-4-oxobut-2-enoic acid

The title compounds, C17H14N2O4 (I) and C15H12N2O4S (II), possess very similar mol-ecular geometries. In both mol-ecules, the central 1,3,5-tris-ubstituted di-hydro-pyrazole ring adopts an envelope conformation. The oxobutenoic acid fragment has an almost planar Z conformation [r.m.s. deviations of 0.049 and 0.022 Å, respectively, for (I) and (II)] which is determined by the both bond conjugation and the strong intra-molecular O-H⋯O hydrogen bond. The substituents in positions 1 and 3 of the di-hydro-pyrazole ring [oxobutenoic acid and phenyl in (I) and oxobutenoic acid and thienyl in (II)] are nearly coplanar with its basal plane [the corresponding dihedral angles are 6.14 (9) and 2.22 (11)° in (I) and 6.27 (12) and 3.91 (11)° in (II)]. The furyl ring plane is twisted relative to the basal plane of the di-hydro-pyrazole ring by 85.51 (8) and 88.30 (7)° in (I) and (II), respectively. In the crystal of (I), mol-ecules form zigzag hydrogen-bonded chains along [001] by C-H⋯O hydrogen bonds, which are further packed in stacks along [100]. Unlike (I), the crystal of (II) contains centrosymmetric hydrogen-bonded dimers formed by pairs of C-H⋯S hydrogen bonds, which are further linked by weak C-H⋯O hydrogen bonds into a three-dimensional framework.

Microwave-assisted stereoselective approach to novel steroidal ring D-fused 2-pyrazolines and an evaluation of their cell-growth inhibitory effects in vitro

Novel ring D-condensed 2-pyrazolines in the Δ(5)-androstene series were efficiently synthesized from 16-dehydropregnenolone or its acetate with different arylhydrazines or methylhydrazine, respectively, under microwave irradiation. The reactions are assumed to occur via hydrazone intermediates, followed by intramolecular 1,4-addition leading to the fused heteroring stereoselectively with a 16α,17α-cis ring junction. The synthesized compounds were subjected to in vitro pharmacological studies of their antiproliferative activities against four human breast (MCF7, T47D, MDA-MB-231 and MDA-MB-361) and three cervical (HeLa, C33A and SiHA) malignant cell lines. Flow cytometry revealed that the most potent agent elicited a cell cycle disturbance.

A monoclinic polymorph of 4-(2H-1,3-benzodioxol-5-yl)-1-(4-methyl-phen-yl)-1H-pyrazol-5-amine

The title compound, C17H15N3O2, is a monoclinic polymorph (P21/c with Z' = 1) of the previously reported triclinic (P-1 with Z' = 2) form [Gajera et al. (2013 ▸). Acta Cryst. E69, o736-o737]. The mol-ecule in the monoclinic polymorph features a central pyrazolyl ring with an N-bound p-tolyl group and a C-bound 1,3-benzodioxolyl fused-ring system on either side of the C atom bearing the amino group. The dihedral angles between the central ring and the N- and C-bound rings are 50.06 (5) and 27.27 (5)°, respectively. The angle between the pendent rings is 77.31 (4)°, indicating the mol-ecule has a twisted conformation. The five-membered dioxolyl ring has an envelope conformation with the methyl-ene C atom being the flap. The relative disposition of the amino and dioxolyl substituents is syn. One of the independent mol-ecules in the triclinic form has a similar syn disposition but the other has an anti arrangement of these substituents. In the crystal structure of the monoclinic form, mol-ecules assemble into supra-molecular helical chains via amino-pyrazolyl N-H⋯N hydrogen bonds. These are linked into layers via C-H⋯π inter-actions, and layers stack along the a axis with no specific inter-actions between them.

4-(2H-1,3-Benzodioxol-5-yl)-1-(4-methyl-phenyl)-1H-pyrazol-5-amine

In the title compound, C17H15N3O2, two independent mol-ecules (A and B) comprise the asymmetric unit. The major conformational difference arises in the relative orientation of the pyrazole ring amine and dioxole substituents which are anti in A and syn in B. The five-membered dioxole ring in each mol-ecule has an envelope conformation with the methyl-ene C atom as the flap. The mean plane through the benzodioxole and benzene groups make dihedral angles of 31.67 (8) and 68.22 (9)°, respectively, with the pyrazole ring in A; the equivalent values for B are 47.18 (7) and 49.08 (9)°. In the crystal, supra-molecular zigzag chains along the b-axis direction arise as a result of N-H⋯N hydrogen bonding. These are consolidated into supra-molecular double chains via C-H⋯O and C-H⋯π inter-actions.

Design, Synthesis, andIn VitroAntioxidant Activity of 1,3,5-Trisubstituted-2-pyrazolines Derivatives

Mannich base of pyrazolines 3(a–e) under both conventional and microwave irradiation was synthesized. All the synthesised compounds were purified by recrystallisation, characterized on the basis of UV, IR, and NMR spectroscopy, and further supported by mass spectroscopy. The result obtained confirms superiority of microwave irradiation method over classical heating one. The molecular properties and Lipinski rule of five for compounds 3(a–e) were determined by Molinspiration. The synthesized compounds were subsequently evaluated for the antioxidant activity. All the compounds were found in compliance with Lipinski “Rule of Five”, and compound 3e havingp-hydroxyl substitution showed best antioxidant activity as compared to ascorbic acid and rutin.