3,4-Diphenyl-1H-pyrazole-1-propanamine antidepressants

On-DNA hydroalkylation of N-vinyl heterocycles via photoinduced EDA-complex activation

The emergence of DNA-encoded library (DEL) technology has provided a considerable advantage to the pharmaceutical industry in the pursuit of discovering novel therapeutic candidates for their drug development initiatives. This combinatorial technique not only offers a more economical, spatially efficient, and time-saving alternative to the existing ligand discovery methods, but also enables the exploration of additional chemical space by utilizing novel DNA-compatible synthetic transformations to leverage multifunctional building blocks from readily available substructures. In this report, a decarboxylative-based hydroalkylation of DNA-conjugated N-vinyl heterocycles enabled by single-electron transfer (SET) and subsequent hydrogen atom transfer through electron-donor/electron-acceptor (EDA) complex activation is detailed. The simplicity and robustness of this method permits inclusion of a broad array of alkyl radical precursors and DNA-tethered nitrogenous heterocyles to generate medicinally relevant substituted heterocycles with pendant functional groups. Moreover, a successful telescoped route provides the opportunity to access a broad range of intricate structural scaffolds by employing basic carboxylic acid feedstocks.

A Structural and In Silico Investigation of Potential CDC7 Kinase Enzyme Inhibitors

A crucial role in the regulation of DNA replication is played by the highly conserved CDC kinase. The CDC7 kinase could serve as a target for therapeutic intervention in cancer. The primary heterocyclic substance is pyrazole, and its derivatives offer great potential as treatments for cancer cell lines. Here, we synthesized the two pyrazole derivatives: 4-(2-(4-chlorophenyl)hydrazinyl)-5-methyl-2-tosyl-1H-pyrazol-3(2H)-one (PYRA-1) and 4-(2-(2,4-difluorophenyl)hydrazinyl)-5-methyl-2-tosyl-1H-pyrazol-3(2H)-one (PYRA-2). The structural confirmation of both the compounds at the three-dimensional level is characterized using single crystal X-ray diffraction and density functional theory. Furthermore, the in silico chemical biological properties were derived using molecular docking and molecular dynamics (MD) simulations. PYRA-1 and PYRA-2 crystallize in the P-1 (a = 8.184(9), b = 14.251(13), c = 15.601(15), α = 91.57(8), β = 97.48(9), 92.67(9), V = 1801.1(3) 3, and Z = 2) and P21/n (a = 14.8648(8), b = 8.5998(4), c = 15.5586(8), β = 116.47(7), V = 1780.4(19) 3, and Z = 4), space groups, respectively. In both PYRA-1 and PYRA-2 compounds, C-H···O intermolecular connections are common to stabilize the crystal structure. In addition, short intermolecular interactions stabilizes with C-H···π and π-π stacking. Crystal packing analysis was quantified using Hirshfeld surface analysis resulting in C···H, O···H, and H···H contacts in PYRA-1 exhibiting more contribution than in PYRA-2. The conformational stabilities of the molecules are same in the gas and liquid phases (water and DMSO). The docking scores measured for PYRA-1 and PYRA-2 with CDC7 kinase complexes are -5.421 and -5.884 kcal/mol, respectively. The MD simulations show that PYRA-2 is a more potential inhibitor than PYRA-1 against CDC7 kinase.

Pyrazole and pyrazoline derivatives as antimalarial agents: A key review

Malaria poses a severe public health risk and a significant economic burden in disease-endemic countries. One of the most severe issues in malaria control is the development of drug resistance in malaria parasites. The standard treatment for malaria is artemisinin-combination therapy (ACT). Nevertheless, the Plasmodium parasite's extensive resistance to prior drugs and reduced ACT efficiency necessitates novel drug discovery. The progress in discovering novel, affordable, and effective antimalarial agents is significant in combating drug resistance, and the hybrid drug concept can be used to covalently link two or more active pharmacophores that may act on multiple targets. Pyrazole and pyrazoline derivatives are considered pharmacologically necessary active heterocyclic scaffolds that possess almost all types of pharmacological activities. This review summarized recent progress in antimalarial activities of synthesized pyrazole and pyrazoline derivatives. The studies published since 2000 are included in this systematic review. This review is anticipated to be beneficial for future study and new ideas in searching for rational development strategies for more effective pyrazole and pyrazoline derivatives as antimalarial drugs.

Visible Light-Promoted Green and Sustainable Approach for One-Pot Synthesis of 4,4'-(Arylmethylene)bis(1H-pyrazol-5-ols), In Vitro Anticancer Activity, and Molecular Docking with Covid-19 Mpro

A visible light-promoted, efficient, green, and sustainable strategy has been adopted to unlatch a new pathway toward the synthesis of a library of medicinally important 4,4'-(arylmethylene)bis(1H-pyrazol-5-ols) moieties using substituted aromatic aldehydes and sterically hindered 3-methyl-1-phenyl-2-pyrazoline-5-one in excellent yield. This reaction shows high functional group tolerance and provides a cost-effective and catalyst-free protocol for the quick synthesis of biologically active compounds from readily available substrates. Synthesized compounds were characterized by spectroscopic techniques such as IR, 1HNMR, 13CNMR, and single-crystal XRD analysis. All the synthesized compounds were evaluated for their antiproliferative activities against a panel of five different human cancer cell lines and compared with Tamoxifen using MTT assay. Compound 3m exhibited maximum antiproliferative activity and was found to be more active as compared to Tamoxifen against both the MCF-7 and MDA-MB-231 cell lines with an IC50 of 5.45 and 9.47 μM, respectively. A molecular docking study with respect to COVID-19 main protease (Mpro) (PDB ID: 6LU7) has also been carried out which shows comparatively high binding affinity of compounds 3f and 3g (-8.3 and -8.8 Kcal/mole, respectively) than few reported drugs such as ritonavir, remdesivir, ribacvirin, favipiravir, hydroxychloroquine, chloroquine, and olsaltamivir. Hence, it reveals the possibility of these compounds to be used as effective COVID-19 inhibitors.

Meglumine-Promoted Eco-Compatible Pseudo-Three-Component Reaction for the Synthesis of 1,1-Dihomoarylmethane Scaffolds and Their Green Credentials

A simple, straightforward, and energy-efficient greener route for the synthesis of a series of biologically interesting functionalized 1,1-dihomoarylmethane scaffolds has been developed in the presence of meglumine as an efficient and eco-friendly organo-catalyst via one-pot pseudo-three-component reaction at room temperature. Following this protocol, it is possible to synthesize 1,1-dihomoarylmethane scaffolds of an assortment of C-H activated acids such as dimedone, 1,3-cyclohexadione, 4-hydroxy-6-methyl-2-pyrone, 4-hydroxycoumarin, and 1-phenyl-3-methyl-pyrazolone. The salient features of the present green protocol are mild reaction conditions, good to excellent yields, operational simplicity, easy isolation of products, no cumbersome post treatment, high atom economy, and low E-factor. In addition, this chemistry portrays several green advantages including the reusability of reaction media and product scalability, which makes protocol sustainably efficient. Additionally, several control experiments such as protection of catalyst reactive site, D₂O exchange, and ¹H NMR studies revealed possible pathways for meglumine-promoted reactions. Inspired by the natural physiological environment of 1,1-dihomoarylmethane scaffolds, we reconnoitered the biological profile of our compounds and synthesized compounds that were promising for their antiproliferative and antibacterial activities.

Successful Dendrimer and Liposome-Based Strategies to Solubilize an Antiproliferative Pyrazole Otherwise Not Clinically Applicable

Water-soluble formulations of the pyrazole derivative 3-(4-chlorophenyl)-5-(4-nitrophenylamino)-1H-pyrazole-4-carbonitrile (CR232), which were proven to have in vitro antiproliferative effects on different cancer cell lines, were prepared by two diverse nanotechnological approaches. Importantly, without using harmful organic solvents or additives potentially toxic to humans, CR232 was firstly entrapped in a biodegradable fifth-generation dendrimer containing lysine (G5K). CR232-G5K nanoparticles (CR232-G5K NPs) were obtained with high loading (DL%) and encapsulation efficiency (EE%), which showed a complex but quantitative release profile governed by Weibull kinetics. Secondly, starting from hydrogenated soy phosphatidylcholine and cholesterol, we prepared biocompatible CR232-loaded liposomes (CR232-SUVs), which displayed DL% and EE% values increasing with the increase in the lipids/CR232 ratio initially adopted and showed a constant prolonged release profile ruled by zero-order kinetics. When relevant, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM) and dynamic light scattering (DLS) experiments, as well as potentiometric titrations completed the characterization of the prepared NPs. CR232-G5K NPs were 2311-fold more water-soluble than the pristine CR232, and the CR232-SUVs with the highest DL% were 1764-fold more soluble than the untreated CR232, thus establishing the success of both our strategies.

One-pot synthesis and antiproliferative activity of highly functionalized pyrazole derivatives

A series of highly functionalized pyrazole derivatives has been prepared by a one-pot, versatile and regioselective procedure. Pyrazoles 1-29 were tested in cell-based assay to assess their antiproliferative activity against a panel of tumour cells. Additionally, the cytotoxicity of prepared compounds was evaluated against normal human fibroblasts. The antiproliferative activity of the synthesized molecules emerged to be affected by the nature of the substituents of the pyrazole scaffold and derivatives 21-23 proved to inhibit the growth of melanoma and cervical cancer cells. Compound 23 was identified as the most active derivative and docking simulations predicted its ability to interact with estrogen receptors.

Metal- and Solvent-Free Cascade Reaction for the Synthesis of Amino Pyrazole Thioether Derivatives

We developed an iodine-mediated cascade strategy to synthesize amino pyrazole thioether derivatives (11) in the absence of metals as well as solvents. The present approach provides amino pyrazole thioethers in a highly selective manner without the formation of diaryl sulfide and sulfenyl-enaminonitrile with broad substrate scope. The reactivity of nine sulfenylation sources and synthetic applications of the synthesized compounds have been demonstrated. Thus, the overall iodine-mediated multicomponent reaction (MCR) is more economically feasible, efficient, and environmentally benign.

Development of New Thiazole Complexes as Powerful Catalysts for Synthesis of Pyrazole-4-Carbonitrile Derivatives under Ultrasonic Irradiation Condition Supported by DFT Studies

In this study, we are interested in preparing Fe(III), Pd(II), and Cu(II) complexes from new thiazole derivatives. All syntheses were elaborately elucidated to estimate their molecular and structural formulae, which agreed with those of mononuclear complexes. The square-planer geometry of Pd(II) complex (MATYPd) was the starting point for its use as a heterocatalyst in preparing pyrazole-4-carbonitrile derivatives 4a-o using ultrasonic irradiation through a facile one-pot reaction. The simple operation, short-time reaction (20 min), and high efficiency (97%) were the special advantages of this protocol. Furthermore, this green synthesis strategy was advanced by examination of the reusability of the catalyst in four consecutive cycles without significant loss of catalytic activity. The new synthesis strategy presented remarkable advantages in terms of safety, simplicity, stability, mild conditions, short reaction time, excellent yields, and use of a H₂O solvent. This catalytic protocol was confirmed by the density functional theory (DFT) study, which reflected the specific characteristics of such a complex. Logical mechanisms have been suggested for the successfully exerted essential physical parameters that confirmed the superiority of the Pd(II) complex in the catalytic role. Optical band gap, electrophilicity, and electronegativity features, which are essential parameters for the catalytic behavior of the Pd(II) complex, are based mainly on the unsaturated valence shell of Pd(II).

Appraisal of the Role of In silico Methods in Pyrazole Based Drug Design

Pyrazole and its derivatives are a pharmacologically and significantly active scaffolds that have innumerable physiological and pharmacological activities. They can be very good targets for the discovery of novel anti-bacterial, anti-cancer, anti-inflammatory, anti-fungal, anti-tubercular, antiviral, antioxidant, antidepressant, anti-convulsant and neuroprotective drugs. This review focuses on the importance of in silico manipulations of pyrazole and its derivatives for medicinal chemistry. The authors have discussed currently available information on the use of computational techniques like molecular docking, structure-based virtual screening (SBVS), molecular dynamics (MD) simulations, quantitative structure activity relationship (QSAR), comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) to drug design using pyrazole moieties. Pyrazole based drug design is mainly dependent on the integration of experimental and computational approaches. The authors feel that more studies need to be done to fully explore the pharmacological potential of the pyrazole moiety and in silico method can be of great help.

Energetic Tricyclic Polynitropyrazole and Its Salts: Proton-Locking Effect of Guanidium Cations

An axisymmetric polynitro-pyrazole molecule, 3,5-di(3,5-dinitropyrazol-4-yl)]-4-nitro-1H-pyrazole (5), and its salts (6-12) were prepared and fully characterized. These compounds not only show promising energetic properties but also show a unique tautomeric switch via combining different cations with the axisymmetric compound (5). Its salts (6-9) remain axisymmetric when the cations are potassium, ammonium, or amino-1,2,4-triazolium. However, when the cations are guanidiums, the salts (10-12) dramatically become asymmetric owing to the fixed proton. The introduction of guanidium cations breaks the tautomeric equilibrium by blocking the prototropic transformations and results in the switch-off effect to tautomerism. The structural constraints of ¹H NMR and ¹³C NMR spectra provide strong evidence for the unusual structural constraint phenomenon. These stabilized asymmetric tautomers are very important from the point of molecular recognition, and this research may promote further developments in synthetic and isolation methodologies for novel bioactive pyrazole-based compounds.

Synthesis and crystal structure of the novel chiral acetyl-3-thiophene-5-(9-anthryl)-2-pyrazoline, C23H18N2OS

C23H18Cl4N2OS, orthorhombic, P212121 (no. 19), a = 16.872(3) Å, b = 10.414(2) Å, c = 10.589(2) Å, V = 1860.5(6) Å3, Z = 4, R gt (F) = 0.0588, wR ref (F 2) = 0.1464, T = 293 K.

Cyanoacetylenic Alcohols: Molecules of Interstellar Relevance in the Synthesis of Essential Heterocycles, Amino Acids, Nucleobases and Nucleosides

Cyanoacetylenic alcohols, R1R2C(OH)C≡C–CN, the closest derivatives of cyanoacetylene, an abundant interstellar molecule, are now becoming important compounds in the area of modern organic synthesis that tends to mimic Nature. The presence of highly reactive C≡C and C≡N bonds in close proximity to a hydroxy group endows cyanoacetylenic alcohols with a chemical trinity of mutually influencing functions, leading to a myriad number of chemical transformations. All reactions of cyanoacetylenic alcohols parallel modern organic synthesis, whilst being biomimetic. To react, they do not need transition metals (and in most cases, no metals at all, except for physiologically indispensable Na+ and K+), proceed at ambient temperature and often in aqueous media. Fundamentally, their reactions are 100% atom-economic because they are almost exclusively addition processes. Typically, the cyano, acetylene and hydroxy functions of cyanoacetylenic alcohols behave as an inseparable entity, leading to reaction products with multiple functional groups. This allows hydroxy, carbonyl, carboxylic, imino, amino, amido, cyanoamido, cyano, various P-containing, ether and ester functions, along with double bonds, different fundamental heterocycles (furans, furanones, pyrazoles, oxazoles, pyridines, pyrimidines, purines, etc.) and diverse polycyclic systems to be integrated in a single molecular architecture. This review focuses on an analysis and generalization of the knowledge that has accumulated on the chemistry of cyanoacetylenic alcohols, mostly over the past 15 years.

1 Introduction

2 Nucleophilic Addition to Cyanoacetylenic Alcohols and Subsequent Transformations of the Adducts

3 Annulation with Nonaromatic Nitrogen Heterocycles

4 Annulation with Aromatic Nitrogen Heterocycles

5 Modification of Amino Acids

6 Modifications of Nucleobases

7 Modification of Nucleosides

8 Conclusion

Chickpea leaf exudates: a green Brønsted acid type biosurfactant for bis(indole)methane and bis(pyrazolyl)methane synthesis

A clean and highly efficient protocol for green synthesis of bis(indole)methanes and bis(pyrazolyl)methanes has been successfully achieved by using a naturally sourced bio-surfactant, chickpea leaf exudates (CLE), as a Brønsted acid-type catalyst.

Recent Advances in the Synthesis of Pyrazole Derivatives

Pyrazole and its derivatives have gained wide attention in pharmaceutical, agrochemical and biological fields as well as in industry. They exhibit various biological activities such as anti-pyretic, anti-microbial, anti- inflammatory, anti-tumor, anti-viral, anti-histaminic, anti-convulsant, fungicidal, insecticidal, etc. In this review, we summarise the recent advances in the synthesis of pyrazole derivatives using various methodologies and covers literature from 2017-2020.

Unprecedented formation of palladium(II)-pyrazole based thiourea from chromone thiosemicarbazone and [PdCl2(PPh3)2]: Interaction with biomolecules and apoptosis through mitochondrial signaling pathway

Two novel pyrazole based thiourea palladium(II) complexes, [PdCl(PPh₃)(C₉H₈NO₂S-pz)] (1) and [PdCl(PPh₃)(C₁₄H₁₀NO₂S-pz)] (2) [pz = pyrazole (C₃H₂N₂)] have been obtained unexpectedly from chromone thiosemicarbazones (L1 and L2) and [PdCl₂(PPh₃)₂]. The compounds have been fully characterized by physicochemical studies. The single crystal X-ray diffraction and spectral studies revealed square planar geometry for the complexes. The conversion of chromone thiosemicarbazone into pyrazole based thiourea might have happened through coordination to palladium(II) ion after enolization, Michael addition and ring opening followed by cyclization. To the best of our knowledge, this is the first report for the conversion of chromone thiosemicarbazone into pyrazole based thiourea moiety. Plausible mechanism was proposed based on the spectroscopic studies. Calf thymus (CT) DNA binding of the compounds was explored using various spectroscopic and molecular docking methods. DNA cleavage studies suggested that complexes 1 and 2 had the capacity to cleave the supercoiled DNA (pUC19) to its naked form. In vitro cytotoxic property of the ligands and complexes has been evaluated against three human cancer cells such as A549, HepG-2 and U937. Complex 2 exhibited potent cytotoxic activity against HepG-2 cells with the IC₅₀ value of 10.4 μM. In addition, mechanistic studies showed that complex 2 induced apoptosis through mitochondrial signaling pathway in HepG-2 cells. Beneficially, complex 2 showed less toxicity against human lung (IMR90) normal cells and hence it emerges as a potential candidate for further studies.

Highly efficient catalyst-free domino conjugate addition, decarboxylation and esterification/amidation of coumarin carboxylic acid/esters with pyrazolones: a green chemistry approach

Tandem conjugate addition, decarboxylation and esterification/amidation of coumarin 3-carboxylic acid derivatives with pyrazolones have been developed.

Crystal structure of ethyl 3-(4-methoxyphenyl)-5-methylcarbamoyl-1H-pyrazole-4-carboxylate, C15H17N3O4

C15H17N3O4, triclinic, P1̄ (no. 2), a = 10.5986(5) Å, b = 11.5298(5) Å, c = 13.5386(6) Å, α = 102.694(1)°, β = 102.999(1)°, γ = 108.918(1)°, V = 1446.03(11) Å3, Z = 4, Rgt(F) = 0.0525, wRref(F2) = 0.1526, T = 100(1) K.

Synthesis and Antioxidant Evaluation of Dihydropyrimidinone Integrated Pyrazoles

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A series of novel ethyl 6-[2-(3-aryl-1-phenyl-1H-pyrazol-4-yl)vinyl]-2-oxo-4-phenyl- 1,2,3,4-tetrahydropyrimidine-5-carboxylates (9a-9d) has been synthesized by adopting a multistep synthetic strategy. The structure of the targets was confirmed on the basis of physical and spectral techniques. The synthetically achieved targets were evaluated for their antioxidant activity by in-vitro DPPH free radical scavenging assay. Of the chemical entities screened, most of them exhibit good to better radical scavenging profile and among those, the nitro substituent bearing molecule 9c displayed the highest activity (82%) with IC50 value 621.6 μM. Further, as a representative molecule, compound 9a has been subjected to density functional theory calculations employing B3LYP method with 6311(++G) basis set to optimize its structure.

Synthesis of novel Schiff bases using 2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile and 1,3-Disubstituted pyrazole-4-carboxaldehydes derivatives and their antimicrobial activity

2-Amino-5-(3-fluoro-4-methoxyphenyl)thiophene-3-carbonitrile have been synthesized from 1-(3-fluoro-4-methoxyphenyl)ethanone, malononitrile, a mild base and sulfur powder using Gewald synthesis technique and the intermediate was treated with 1,3-disubstituted pyrazole-4-carboxaldehyde to obtain the novel Schiff bases. 1,3-disubstituted pyrazole-4-carboxaldehyde derivatives have been synthesized by Vilsmeier-Haack reaction in the course of a multi-step reaction. The structure of novel compounds were established on the basis of their elemental analyses IR, ¹H NMR, ¹³C NMR, and mass spectral data and then screened for their in vitro antimicrobial activity. Among them 5a, 5c, 5f and 5h showed excellent activity when compared to other derivatives. Remaining derivatives showed moderate activity.