Journal articles: 'Pyrazole'

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Abaszadeh, Mehdi, Hassan Sheibani, and Kazem Saidi. "The Condensation of (Chlorocarbonyl)phenyl Ketene with Bisnucleophiles. Synthesis of 4-Hydroxy-5-phenylpyro-[2,3-c]pyrazol-6-ones and Formation of Pyrazolo[1,2-a]pyrazole-triones by Hydrogen Exchange in Unstable Mesoionic Compounds." Australian Journal of Chemistry 63, no. 1 (2010): 92. http://dx.doi.org/10.1071/ch09344.

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The addition of (chlorocarbonyl)phenyl ketene 2 to 5-alkylpyrazol-3(4H)-ones 1 led to the formation of 3-hydroxypyrazolo[1,2-a]pyrazole-dione/pyrazolo[1,2-a]pyrazole-trione derivatives 3. This is ascribed to hydrogen exchange in initially formed unstable, mesoionic pyrazolo[1,2-a]pyrazol-4-ium-5-olates. In contrast, condensation of the same ketene with 3-alkyl-1-phenyl-2-pyrazolin-5-ones 4 afforded 4-hydroxy-3-alkyl-1,5-diphenylpyrano[2,3-c]pyrazol-6-one derivatives 5. The latter reaction provides a new and rapid route to 4-hydroxy-2-pyrones fused to pyrazole rings, in good to excellent yields.

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Alsayari, Abdulrhman, Abdullatif Bin Muhsinah, Yahya I. Asiri, Jaber Abdullah Alshehri, Yahia N. Mabkhot, Mohammad Y. Alfaifi, Serag Eldin I. Elbehairi, Mater H. Mahnashi, and Mohd Zaheen Hassan. "Arylhydrazono/Aryldiazenyl Pyrazoles: Green One-Pot Solvent-Free Synthesis and Anticancer Evaluation." Letters in Organic Chemistry 17, no. 10 (November 17, 2020): 772–78. http://dx.doi.org/10.2174/1570178617666200320104923.

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The aim of this study was to synthesize and evaluate the biological activity of pyrazole derivatives, in particular, to perform a “greener” one-pot synthesis using a solvent-free method as an alternative strategy for synthesizing hydrazono/diazenyl-pyridine-pyrazole hybrid molecules with potential anticancer activity. Effective treatment for all types of cancers is still a long way in the future due to the severe adverse drug reactions and drug resistance associated with current drugs. Therefore, there is a pressing need to develop safer and more effective anticancer agents. In this context, some hybrid analogues containing the bioactive pharmacophores viz. pyrazole, pyridine, and diazo scaffolds were synthesized by one-pot method. Herein, we describe the expedient synthesis of pyrazoles by a onepot three-component condensation of ethyl acetoacetate/acetylacetone, isoniazid, and arenediazonium salts under solvent-free conditions, and the evaluation of their cytotoxicity using a sulforhodamine B assay on three cancer cell lines. Molecular docking studies employing tyrosine kinase were also carried out to evaluate the binding mode of the pyrazole derivatives under study. 1-(4-Pyridinylcarbonyl)-3- methyl-4-(2-arylhydrazono)-2-pyrazolin-5-ones and [4-(2-aryldiazenyl)-3,5-dimethyl-1H-pyrazol-1- yl]-4-pyridinylmethanones, previously described, were prepared using an improved procedure. Among these ten products, 1-isonicotinoyl-3-methyl-4-[2-(4-nitrophenyl)hydrazono]-2-pyrazolin-5-one (1f) displayed promising anticancer activity against the MCF-7, HepG2 and HCT-116 cell lines, with an IC50 value in the range of 0.2-3.4 μM. In summary, our findings suggest that pyrazoles containing hydrazono/ diazenyl and pyridine pharmacophores constitute promising scaffolds for the development of new anticancer agents.

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Sophy, Mohamed Ahmed Elian, and Mohamed Ahmed Mahmoud Abdel Reheim. "Synthesis of Some New 1, 3, 4-Oxadiazole, Pyrazole, and Pyrimidine Bearing Thienopyrazole Moieties." Current Organic Synthesis 17, no. 8 (October 28, 2020): 661–70. http://dx.doi.org/10.2174/1570179417999200730215318.

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Aim and Objective: According to the literature survey, pyrazole is a unique template that is associated with several biological activities. This article highlighted the research work of many researchers reported in the literature for synthesis and different pharmacological activities of the pyrazole nucleus. In the present work, pyrazol- 3-one 1 was reacted with cyanoacetic acid hydrazide and elemental sulfur to afford the corresponding thieno[3,2-c]pyrazol-6-carbohydrazide 3 derivatives. The latter compound reacted with some electrophilic reagents such as DMF-DMA, triethylorthoformate, arylidenemalononitriles and chalcones under neat conditions to give substituted oxadiazole and pyrazole, respectively. The treatment of compound 3 with active methylene reagents such as acetylacetone, diethylmalonate, ethyl acetoacetate and ethyl cyanoacetate under suitable conditions afforded pyrazole derivatives 10, 11, 13, and 15, respectively. Novel pyrazolothienopyrimidine 27 and 30 were prepared from precursor 26 with carbon disulfide and triethylorthoformate, respectively. The chemical structures of the newly synthesized compounds were established by elemental and spectral analyses including IR, and 1HNMR in addition to 13C-NMR and mass spectra. Materials and Methods: A novel substituted pyrazole, pyrimidine and pyrazolothienopyrimidine were obtained via Gewald synthesis of thiophene and fused thiophene and Mannich reactions of 5-amino-3-phenyl-1Hthieno[ 3,2-c]pyrazole-6-carbohydrazide. Results and Discussion: A series of some newly azoles and azines were prepared via reaction of thieno[3,2- c]pyrazol-6-carbohydrazide derivative 3 as starting material with some electrophilic and nucleophilic reagents. The structures of target compounds were established by elemental analyses and spectral data. Conclusion: Pyrazole is a unique template that is associated with several biological activities. This article highlighted the research work of many researchers reported in the literature for synthesis and different pharmacological activities of the pyrazole nucleus. In the current investigation, we have developed new and efficient methods for the synthesis of thieno[3,2-c]pyrazol-6-carbohydrazide derivatives. In addition, we have explored the preparative potential of these substances as intermediates for the synthesis of substituted pyrazoles and fused pyrazoles 10-30, respectively.

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Hartwig de Oliveira, Daniela, Fernanda Severo Sabedra Sousa, Paloma Taborda Birmann, Ana Paula Pesarico, Diego Alves, Raquel Guimarães Jacob, and Lucielli Savegnago. "Evaluation of antioxidant activity and toxicity of sulfur- or selenium-containing 4-(arylchalcogenyl)-1H-pyrazoles." Canadian Journal of Physiology and Pharmacology 98, no. 7 (July 2020): 441–48. http://dx.doi.org/10.1139/cjpp-2019-0356.

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Pyrazoles represent a significant class of heterocyclic compounds that exhibit pharmacological properties. The present study aimed to investigate the antioxidant potential of pyrazol derivative compounds in brain of mice in vitro and the effect of pyrazol derivative compounds in the oxidative damage and toxicity parameters in mouse brain and plasma of mice. The compounds tested were 3,5-dimethyl-1-phenyl-4-(phenylselanyl)-1H-pyrazol (1a), 3,5-dimethyl-4-(phenylselanyl)-1H-pyrazole (2a), 4-((4-methoxyphenyl)selanyl)-3,5-dimethyl-1-phenyl-1H-pyrazole (3a), 4-((4-chlorophenyl)selanyl)-3,5-dimethyl-1-phenyl-1H-pyrazole (4a), 3,5-dimethyl-1-phenyl-4-(phenylthio)-1H-pyrazole (1b), 3,5-dimethyl-4-(phenylthio)-1H-pyrazole (2b), 4-((4-methoxyphenyl)thio)-3,5-dimethyl-1-phenyl-1H-pyrazole (3b), 4-((4-chlorophenyl)thio)-3,5-dimethyl-1-phenyl-1H-pyrazole (4b), and 3,5-dimethyl-1-phenyl-1H-pyrazole (1c). In vitro, 4-(arylcalcogenyl)-1H-pyrazoles, at low molecular range, reduced lipid peroxidation and reactive species in mouse brain homogenates. The compounds also presented ferric-reducing ability as well nitric oxide-scavenging activity. Especially compounds 1a, 1b, and 1c presented efficiency to 1,1-diphenyl-2-picryl-hydrazyl-scavenging activity. Compounds 1b and 1c presented 2,20 -azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)-scavenging activity. In vivo assays demonstrated that compounds 1a, 1b, and 1c (300 mg/kg, intragastric, a single administration) did not cause alteration in the of δ-aminolevulinic acid dehydratase activity, an enzyme that exhibits high sensibility to prooxidants situations, in the brain, liver, and kidney of mice. Compound 1c reduced per se the lipid peroxidation in liver and brain of mice. Toxicological assays demonstrate that compounds 1a, 1b, and 1c did not present toxicity in the aspartate aminotransferase, alanine aminotransferase, urea, and creatinine levels in the plasma. In conclusion, the results demonstrated the antioxidant action of pyrazol derivative compounds in in vitro assays. Furthermore, the results showed low toxicity of compounds in in vivo assays.

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5

Lindsay-Scott, Peter J., and Eloise Rivlin-Derrick. "Regiocontrolled Synthesis of 6,7-Dihydro-4H-pyrazolo[5,1-c][1,4]oxazines." Synthesis 52, no. 01 (October 8, 2019): 105–18. http://dx.doi.org/10.1055/s-0037-1610734.

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Synthetic access to 6,7-dihydro-4H-pyrazolo[5,1-c][1,4]oxazines has been achieved in 3–4 steps from commercially available pyrazoles. Optimization of a protected hydroxyethyl group on N1 enabled the regiocontrolled construction of pyrazole-5-aldehydes in high yields; subsequent deprotection and reduction generated fused heterocyclic scaffolds bearing multiple substitution patterns. Moreover, the intermediate pyrazole lactols were shown to be versatile synthetic building blocks.

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Andicsová, Anita, Angelika Lásiková, Marek Fronc, Jozef Kožíšek, and Daniel Végh. "3-(2-Heteroaryl)-pyrazolotetrazoles – a subunits for losartan-like structures." Acta Chimica Slovaca 5, no. 2 (November 1, 2012): 220–24. http://dx.doi.org/10.2478/v10188-012-0033-z.

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Abstract A modification of biphenylyltetrazole moiety of Losartan (A) by 3-(2-heteroaryl)-pyrazolotetrazole (B) is described. Ketone semicarbazones react with two moles of phosphorus oxychloride-dimethylformamide with the formation of 3-substituted pyrazol-4-carbaldehydes. The transformations of 3-substituted pyrazole-4- carboxaldehydes to 3-substituted pyrazole-4-nitriles were carried out by reaction of hydroxylamine in DMFA. The prepared cyano pyrazoles were converted to tetrazoles by heating with trimethylsilylazide and dibuthyltinoxide in toluene.

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7

Srinivasa Reddy, T., Hitesh Kulhari, V. Ganga Reddy, A. V. Subba Rao, Vipul Bansal, Ahmed Kamal, and Ravi Shukla. "Synthesis and biological evaluation of pyrazolo–triazole hybrids as cytotoxic and apoptosis inducing agents." Organic & Biomolecular Chemistry 13, no. 40 (2015): 10136–49. http://dx.doi.org/10.1039/c5ob00842e.

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A series of pyrazolo–triazole hybrids were designed and synthesized by combining the 1,3-diphenyl pyrazole and triazole scaffolds to obtain (1-benzyl-1H-1,2,3-triazol-4-yl)(1,3-diphenyl-1H-pyrazol-4-yl)methanones.

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8

Lerner, Hans-Wolfram, Günter Margraf, Tonia Kretz, Olav Schiemann, Jan W. Bats, Gerd Dürner, Fabrizia Fabrizi de Biani, Piero Zanello, Michael Boltea, and Matthias Wagner. "Redox Behaviour of Pyrazolyl-Substituted 1,4-Dihydroxyarenes: Formation of the Corresponding Semiquinones, Quinhydrones and Quinones." Zeitschrift für Naturforschung B 61, no. 3 (March 1, 2006): 252–64. http://dx.doi.org/10.1515/znb-2006-0304.

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Abstract Pyrazolyl-substituted 1,4-dihydroxybenzene and 1,4-dihydroxynaphthene derivatives have been synthesized by reaction of 1,4-benzoquinone and 1,4-naphthoquinone, respectively, with pyrazole. Cyclovoltammetric measurements have shown that 1,4-benzoquinone possesses the potential to oxidize 2-(pyrazol-1-yl)- and 2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene. The 2,5-bis(pyrazol-1-yl)- 1,4-dihydroxybenzene reacts with air to give quantitatively black insoluble 2,5-bis(pyrazol-1-yl)-1,4- quinhydrone. Black crystals of 2,5-bis(pyrazol-1-yl)-1,4-quinhydrone suitable for X-ray diffraction were grown from methanol at ambient temperature (monoclinic C2/c). The poor yields of pyrazolylsubstituted 1,4-dihydroxybenzene and 1,4-dihydroxynaphthene derivatives can be explained by the formation of insoluble black quinhydrons in the reaction of benzoquinone and naphthoquinone with pyrazole. The dianions of 2-(pyrazol-1-yl)- and 2,5-bis(pyrazol-1-yl)-1,4-dihydroxybenzene react with oxygen to give the corresponding semiquinone anions. 2,5-Bis(pyrazol-1-yl)-1,4-benzoquinone shows two reversible one-electron reduction processes in cyclovoltammetric measurements, whereas pyrazolyl-substituted 1,4-dihdroxybenzene and -naphthene derivatives undergo irreversibile electrontransfer processes.

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9

Alsayari, Abdulrhman, Yahya I. Asiri, Abdullatif Bin Muhsinah, and Mohd Zaheen Hassan. "Anticolon Cancer Properties of Pyrazole Derivatives Acting through Xanthine Oxidase Inhibition." Journal of Oncology 2021 (July 5, 2021): 1–5. http://dx.doi.org/10.1155/2021/5691982.

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Background. Pyrazoles are an interesting class of compounds showing potent anticancer activities. Our previous studies have demonstrated the potent anticancer activity of pyrazole analogues. Therefore, we focused on developing anticancer agents through structure optimization of the pyrazolyl lead molecule. Methods. The pyrazole derivatives were prepared by the appropriate synthetic protocols. The antiproliferative activities were evaluated using a sulforhodamine B assay against three cancer cell lines. In vitro and in silico molecular docking studies employing xanthine oxidase were used to explore the mechanism by which pyrazole derivatives exert anticancer effects. Results. One of the pyrazole derivatives demonstrated the greatest promise as an anticancer agent against the human colon cancer cell line (IC50 4.2 μM), with a potent xanthine oxidase inhibitory activity (IC50 0.83 μM). Conclusion. In summary, our findings suggest that these pyrazolyl analogues containing a pyridine nucleus could serve as a promising lead molecule in the development of novel anticancer agents.

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Farooq, Saba, and Zainab Ngaini. "Chalcone Derived Pyrazole Synthesis via One-pot and Two-pot Strategies." Current Organic Chemistry 24, no. 13 (October 1, 2020): 1491–506. http://dx.doi.org/10.2174/1385272824999200714101420.

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Pyrazole is an imperative heterocyclic molecule in the synthetic and medicinal fields. Pyrazole is stable compound that is particularly used in pharmaceutical applications (i.e., anticancer, antifungal, antiviral, antimicrobial and antioxidant) and electronic industries. This review depicted the synthesis of pyrazoles derivatives by employing chalcone derivatives as a starting material via one and two-pot strategies. The one-pot strategy is an exclusive method for chalcone cyclization and oxidation, while two-pot strategy is reported through the preparation of chalcone derivatives, i.e., pyrazoline, hydrazone and bromochalcone prior to the synthesis of pyrazole. One-pot strategy is frequently reported for pyrazole synthesis purposes due to unique, stable, reactive and well-known chalcone reactants having easy handing then two-pot strategy. This review is momentous in organic chemistry, especially synthesis related to pyrazole and drug industry.

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Ramadan, El Sayed, Essam M. Sharshira, Ramadan I. El Sokkary, and Noussa Morsy. "Synthesis and antimicrobial evaluation of some heterocyclic compounds from 3-aryl-1-phenyl-1H-pyrazole-4-carbaldehydes." Zeitschrift für Naturforschung B 73, no. 6 (June 27, 2018): 389–97. http://dx.doi.org/10.1515/znb-2018-0009.

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AbstractA new series of chalcones, pyrazolinyl-pyrazoles, pyrazole-4-carbaldehyde oximes, pyrazole-4-carbonitriles, 5-pyrazolyl-1,2,4-triazolidine-3-thiones, and Knoevenagel condensation products was synthesized from 3-aryl-1-phenyl-1H-pyrazole-4-carbaldehydes. Most reactions were carried out either without solvent or in the presence of water as a green solvent. The structure of synthesized compounds was characterized by spectral and elemental analysis. The synthesized compounds were tested in vitro for their antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans in comparison with imipenem (intravenous β-lactam antibiotic) and clotrimazole (antifungal medication) as reference drugs by using the agar diffusion technique. 3-Aryl-1-phenyl-1H-pyrazole-4-carbonitriles 8b, 8c, and 8d showed significant antifungal activity against the fungus C. albicans.

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Hrynyshyn, Yevhenii, Hanna Musiichuk, Olena Komarovska-Porokhnyavets, Oksana Is’kiv, Nataliia Moskalenko, Maryna Stasevych, Nazar Tsyzoryk, and Mykhailo Vovk. "Synthesis and Antimicrobial Activity of 4-Arylthio- and 4 Alkylthiofunctionalized Pyrazolo[1,5-a]pyrazines." Ukrainian Chemistry Journal 85, no. 1 (February 15, 2019): 58–66. http://dx.doi.org/10.33609/0041-6045.85.1.2019.58-66.

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The reaction of pyrazolo[1,5-a]pyrazine-4(5H)ones with phosphorus tribromoxide in boiling benzene yielded 4-bromopyrazolo[1,5-a]pyrazines, and the thionation with phosphorus pentasulfide in pyridine at 90 °C led to pyrazolo[1,5-a]pyrazine-4(5H)thiones. The synthesized bromine derivatives are electrophilic, and thiones are nucleophilic substrates. Their subsequent structural modification in the first case was carried out by interaction with thiophenols, and in the second case was conducted with functional halogenoalkanes. It was shown that bromides react with substituted thiophenols in dimethylformamide in the presence of potassium carbonate at 90 °C to form 4-arylthiopyrazolo[1,5-a]pyrazines with yields of 65–83 %. 4-S-methyl-functionalized derivatives of pyrazole[1,5-a]pyrazines with yields of 60–78 % were easily obtained by the alkylation of pyrazole[1,5-a]pyrazin-4(5H)thiones with a-bromoketones, bromoacetic acid, ethyl bromoacetate and bromoacetonitrile in the K2CO3—DMF system at room temperature. The composition of all synthesized compounds is in agreement with the results of elemental analysis and mass spectra. Their structure is confirmed by NMR 1H and 13C spectra. In particular, in the NMR 1H spectra of 4-arylthiopyrazolo[1,5-a]pyrazines, in addition to the characteristic signals of the pyrazole and pyrazine nuclei, signals of protons of thioaryl substituents are present in the range of 7.04 –8.05 ppm, and in NMR spectra of the 1H 4-S-methylfunctionalized derivatives of pyrazole[1,5-a]pyrazines signals of exocyclic methylene protons are present at 4.11– 5.02 ppm. Promising derivatives with antibacterial activity against the test cultures S. aureus (MIC = 7.8 g/mL), M. luteum (MIC = 3.9 g/mL), and antifungal activity against the test culture of fungus A. niger (MIC = 7.8 g/mL) were determined among 4-S-substituted pyrazole[1,5-a]pyrazines as a result of studies of the antimicrobial activity.

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Deacon, Glen B., Peter C. Junk, and Aron Urbatsch. "Lanthanoid and Alkaline Earth Complexes Involving New Substituted Pyrazolates." Australian Journal of Chemistry 65, no. 7 (2012): 802. http://dx.doi.org/10.1071/ch12069.

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From the pyrazoles 3,5-di-(2′-furanyl)pyrazole (fu2pzH), 3-phenyl-5-(2′-thienyl)pyrazole (PhtpzH) and 3-(2′-furanyl)-5-(2′′-naphthyl)pyrazole (funappzH), a range of alkaline earth and lanthanoid pyrazolate complexes has been prepared by redox transmetallation/protolysis reactions between free metals, Hg(C6F5)2 and the pyrazoles, by reaction of I2‐activated metals with the pyrazoles, and in one case by a similar reaction of unactivated metal, in the donor solvents tetrahydrofuran (thf) and 1,2-dimethoxyethane (dme). Thus the divalent [Ca(Phtpz)2(thf)4], [Ba(Phtpz)2(thf)4] and [Ca(funappz)2(thf)4]·(thf) complexes, the heteroleptic [Yb(Phtpz)I(thf)4] and the trivalent [La(fu2pz)3(thf)3]·2thf complex have been prepared and structurally characterized, as well as the dme complexes [Yb(Phtpz)2(dme)2] and [Eu(Phtpz)3(dme)2]. Highlights include the first trans-[LnII(pz)I(thf)4] complex, a rare transoid [Ln(pz)2(dme)2] complex and a complex with both chelating and unidentate dme. In all cases, the Phtpz complexes exhibit pronounced positional disorder of the 2-thienyl and phenyl groups in the solid state, as do the two polymorphs of the parent pyrazole.

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Milišiūnaitė, Vaida, Rūta Paulavičiūtė, Eglė Arbačiauskienė, Vytas Martynaitis, Wolfgang Holzer, and Algirdas Šačkus. "Synthesis of 2H-furo[2,3-c]pyrazole ring systems through silver(I) ion-mediated ring-closure reaction." Beilstein Journal of Organic Chemistry 15 (March 14, 2019): 679–84. http://dx.doi.org/10.3762/bjoc.15.62.

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Fused pyrazole ring systems are common structural motifs of numerous pharmaceutically important compounds. Nevertheless, access to derivatives of the aromatic 2H-furo[2,3-c]pyrazole ring system is still quite limited, and their chemistry and functional properties remain largely underexplored. The current study investigates routes to construct this system from easily accessible starting materials using metal-catalyzed reactions. A simple and efficient procedure to access the 2H-furo[2,3-c]pyrazole ring system was developed by employing the silver(I) ion-mediated ring-closure reaction of 4-alkynyl-3-hydroxy-1-phenyl-1H-pyrazoles as a key step. The required intermediate hydroxyalkynyl substrates for this reaction were prepared by a Pd-catalyzed coupling of 4-iodo-1-phenyl-1H-pyrazol-3-ol with ethyne derivatives. The structures of the obtained target compounds were unequivocally confirmed by detailed 1H, 13C and 15N NMR spectroscopic experiments, HRMS and a single-crystal X-ray diffraction analyses. This silver(I)-mediated 5-endo-dig cyclization of readily available 4-alkynyl-3-hydroxy-1H-pyrazoles can be used as an efficient method to access many novel 2,5-disubstituted 2H-furo[2,3-c]pyrazoles.

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Thirunarayanan, Ganesamoorthy, and K. Ravi. "Synthesis and Spectral Correlation Study of some 3-(3,4-dichlorophenyl)-5-(Substituted Phenyl)-4,5-dihydro-¹H-Pyrazole-1-yl-Ethanones." International Letters of Chemistry, Physics and Astronomy 19 (October 2013): 44–57. http://dx.doi.org/10.18052/www.scipress.com/ilcpa.19.44.

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Some N-acetyl pyrazoles including 3-(3,4-dichlorophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-yl-ethanones have been synthesised by solvent free cyclization cum acetylation of chalcones including substituted styryl 3,4-dichlorophenyl ketones using hydrazine hydrate and acetic anhydride in presence of catalytic amount of fly-ash: H2SO4 catalyst. The yield of these N-acetyl pyrazole derivatives are more than 75%. The synthesised N-acetyl pyrazoline derivatives were characterized by their physical constants and spectral data. The infrared spectral νC=N and C=O (cm-1) frequencies, NMR chemical shifts (δ, ppm) of Ha, Hb, Hc, CH3 protons, C=N, C=O and CH3 carbons of 1-(3-(3,4-dichlorophenyl)-5-(substitutedphenyl)-4,5-dihydro-1H-pyrazole-1-yl) ethanones have been assigned and correlated with Hammett substituent constants and Swain-Lupton’s parameters using single and multi-regression analysis. From the results of statistical analyses the effect of substituents on the above group frequencies and chemical shifts of the acetylated pyrazoles were discussed.

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Rizk, Sameh, Ismail M. Awheda, and Fathi A. Smida. "Synthesis and DFT Study of Newly Schiff Base and Fused Heterocyclic Compounds as Antibacterial Agent." JOURNAL OF ADVANCES IN CHEMISTRY 16 (November 7, 2019): 5395–403. http://dx.doi.org/10.24297/jac.v16i0.8499.

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Treatment of 2,3-di-(4-chlorophenyl) oxirane-2,3-dicarbonitriles(1) with nitrogen nucleophiles, e.g. N2H4, NH2OH afforded pyrazole 2, 1.2oxazole 3 derivatives respectively The 3-amino pyrazole-4-one derivatives 2 can be used as a key starting materials to synthesize some important Schiff base 4 and fused heterocyclic compounds e.g. Imidazolo-[4,5-c]pyrazole 5, Pyrazolo[3,4-e]1,2,4-triazine 6, pyrazol[1,2-a] 1,3,5-triazine 7, 8 and 9. The electromeric effect of the halogen atom in the aryl moieties can be controlled upon the rate of reaction and the yield of the product. The structures of synthesized new compounds were characterized by spectral data and screened for their antimicrobial activities against various bacteria and fungi strains. The heterocyclic compounds 7, 8 and 9 that contained bridgehead nitrogen gave an excellent result.

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Gerster, Holger, Michael Keim, and Gerhard Maas. "Cycloaddition reactions of acetylenic iminium salts and diazoacetates leading to pyrazole iminium salts." Zeitschrift für Naturforschung B 74, no. 4 (April 24, 2019): 347–55. http://dx.doi.org/10.1515/znb-2019-0001.

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AbstractAcetylenic iminium triflates with the general formula [R–C≡ C–C(Ar)=N+R2 TfO−] were found to be excellent dipolarophiles in [3+ 2] cycloaddition reactions with diazoacetates leading to (1H-pyrazol-3(5)-yl)methanaminium triflates in high yields. The terminal acetylenic iminium salt (propyne iminium salt) [HC≡C–C(Ph)=N+Me2 TfO−] reacted with an equimolar amount of methyl diazoacetate instantaneously at 20°C to form the expected pyrazole in almost quantitative yield. When a 2:1 stoichiometry was applied, subsequent Michael addition of the pyrazole at the alkyne occurred and the bis(iminium) ditriflate 4 was obtained in high yield. By hydride reduction or hydrolysis of the iminium group, some of the highly hygroscopic pyrazole iminium salts were converted into neutral, twofold functionalized, di- and tri-C-substitued 1H-pyrazoles.

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Bertolasi, Valerio, Paola Gilli, Valeria Ferretti, Gastone Gilli, and Cristina Fernàndez-Castaño. "Self-assembly of NH-pyrazoles via intermolecular N—H...N hydrogen bonds." Acta Crystallographica Section B Structural Science 55, no. 6 (December 1, 1999): 985–93. http://dx.doi.org/10.1107/s0108768199004966.

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The crystal structures of two NH-pyrazole derivatives forming intermolecular N—H...N hydrogen bonds are reported: 5-methyl-4-(3-methylpyrazol-5-yl)pyrazol-3-ol, C8H10N4O (P1), and 3-methyl-5-dihydro-1H-naphtho[1,2-d]pyrazole hemihydrochloride, C12H12N2.-C12H13N_{2}^{+}.Cl− (P2). 26 other structures are surveyed in order to obtain a deeper insight into the ways NH-pyrazoles self-assemble by means of intermolecular N—H...N hydrogen bonds in molecular crystals. A limited number of compounds form chains or dimers via homonuclear N+—H...N positive-charge-assisted hydrogen bonds, typical of proton sponges, which can be remarkably short [e.g. N...N 2.714 (3), N—H 1.09 (3), H...N 1.63 (3) Å, N—H...N 169 (3)° in (P2)]. Most pyrazoles, however, pack via neutral N—H...N bonds which are formally assisted by resonance (resonance-assisted hydrogen bond, RAHB) through the ...N=C—C=C—NH... iminoenamine fragment, contained in the ring, giving rise to dimers, trimers, tetramers and infinite chains of pyrazole molecules. Surprisingly, the resonance does not appear to shorten the N—H...N bond with respect to the accepted mean value N...N 2.97 (10) Å for non-resonant N—H...N bonds. It is shown that this is due to the internal π-delocalization of the pyrazole ring, which can be hardly increased by the hydrogen-bond interaction, except in symmetrically 3,5-substituted pyrazoles which display N...N distances as short as 2.82 Å, identical C—C and C—N distances in the two halves of the pyrazole molecule, and typical phenomena of N—H...N dynamical proton disorder, detectable by 15N-CP/MAS solid-state NMR.

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Chirkova, Zhanna V., Sergey I. Filimonov, and Igor G. Abramov. "SYNTHESIS OF BENZOFURAN-5,6-DICARBONITRILES ANNELATED WITH PYRAZOLE CYCLE." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENIY KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 60, no. 6 (July 19, 2017): 45. http://dx.doi.org/10.6060/tcct.2017606.5576.

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The principal method for the preparation of substituted 4-formyl-1H-pyrazoles was the treatment of hydrazones of different structure with Vilsmeier-Haack reagent. However, for the heterocyclic benzofuran system this reaction is rarely used. Synthetic methods for preparation of novel substituted 3-(4-fomyl-1H-pyrazole-3-yl)-2-methylbenzofuran-5,6-dicarbonitriles and 2-(1H-pyrazole-4-yl)-benzofuran-5,6-dicarbonitriles were developed by modification of 2,3-disubstituted benzofuran-5,6-dicarbonitriles via Vilsmeier-Haack reaction. New substituted 3-(4-fomyl-1H-pyrazole-3-yl)-2-methylbenzofuran-5,6-dicarbonitriles were obtained by reacting 3-acetyl-2-methyl-1-benzofuran-5,6-dicarbonitrile with hydrochloric substituted phenylhydrazines followed by treatment with the Vilsmeier reagent formed hydrazones. A new method for the synthesis of 3-substituted 2-(1H-pyrazol-4-yl)-benzofuran-5,6-dicarbonitriles was based on condensation of aminovinylbenzofuranes with hydrazine hydrate in refluxing acetic acid. The structure of synthesized compounds was determined by data of the IR and NMR spectroscopy, including two-dimensional correlation 1H-1H spectroscopy, and mass spectrometry. The signals of cyano and formyl groups were characteristic in IR spectra; the signals of phthalonitrile protons and proton of aldehyde group - in 1H NMR spectra for 3-(4-formyl-1H-pyrazole)-2-methyl-1-benzofuran-5,6-dicarbonitriles. Also, structure of synthesized 4-formylpyrazoles is confirmed by their reaction with hydrazine hydrate to give corresponding hydrazones. The signals of NH-pronon of pyrazole ring, cyano and carbonyl groups were characteristic in IR spectra; signal broadened singlet of NH-proton of pyrazole ring, which determined to prototropic ring tautomerism of pyrazole ring, and singlets of phthalonitrile protons - in 1H NMR spectra for 3-substituted 2-(1H-pyrazol-4-yl)-benzofuran-5,6-dicarbonitriles. Development of methods for the synthesis of new 4-formylpyrazoles is an important task because the compounds exhibit various pharmacological properties: antimicrobial, anti-inflammatory, antituberculosis, antitumoral, antiparasitic, and antiviral.Forcitation:Chirkova Zh.V., Filimonov S.I., Abramov I.G. Synthesis of benzofuran-5,6-dicarbonitriles annelated with pyrazole cycle. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 6. P. 45-51.

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20

Mague, Joel T., Shaaban K. Mohamed, Mehmet Akkurt, Talaat I. El-Emary, and Mustafa R. Albayati. "Crystal structure of 5-(4,5-dihydro-1H-imidazol-2-yl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]pyrazin-6-amine." Acta Crystallographica Section E Structure Reports Online 70, no. 11 (October 31, 2014): o1212—o1213. http://dx.doi.org/10.1107/s160053681402354x.

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In the title compound, C15H15N7, the phenyl ring is inclined by 19.86 (5)° to the mean plane of the pyrazolo[3,4-b]pyrazine core. In the crystal, N—H...N and C—H...N hydrogen bonds form [010] chains, which stackviaπ–π interactions [centroid–centroid distance between the pyrazole rings = 3.4322 (7) Å].

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21

Warkentin, John, and John Mck R. Woollard. "Photolysis of 5,5-dibenzyl-Δ3-1,3,4-oxadiazolines." Canadian Journal of Chemistry 75, no. 3 (March 1, 1997): 289–307. http://dx.doi.org/10.1139/v97-033.

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Photolysis of dibenzyl-Δ3-1,3,4-oxadiazolines (3) in the presence of dimethyl acetylenedicarboxylate (DMAD) gives only modest yields of the expected symmetrical 3,3-dibenzylcyclopropenes (4), but these are accompanied by more than six by-products, including unsymmetrical cyclopropenes, methylenecyclopropanes, and various pyrazoles. The origin of this array of products can be explained by a series of steps starting with photolysis of 3 to form a diazoalkane that undergoes 1,3-dipolar cycloaddition to DMAD, generating a 3H-pyrazole as initial product. The latter is further photolyzed to a symmetrical cyclopropene in competition with benzyl group migration by thermal 1,5-sigmatropic or ion-pair rearrangement to afford a 4H-pyrazole. The 4H-pyrazole in turn undergoes photolysis to an unsymmetrical cyclopropene, which rearranges to a methylenecyclopropane. The 4H-pyrazole also undergoes autoxidation, in the presence of air, to afford a benzoyl-4H-pyrazole. Additionally, in competition with rearrangement, the various pyrazoles lose a benzyl group or a methoxycarbonyl group to afford pyrazoles with one less substituent. Keywords: 5,5-dibenzyl-Δ3-1,3,4-oxadiazolines, photolysis of; 3,3-dibenzyl-3H-pyrazoles, rearrangement of; 3,4-dibenzyl-4H-pyrazoles, autoxidation of; 3,4-dibenzyl-4H-pyrazoles, photolysis of; cyclopropenes, rearrangement to methylenecyclopropanes.

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22

Farag, Awatef A., Mohamed F. El Shehry, Samir Y. Abbas, Safaa N. Abd-Alrahman, Abeer A. Atrees, Hiaat Z. Al-basheer, and Yousry A. Ammar. "Synthesis of pyrazoles containing benzofuran and trifluoromethyl moieties as possible anti-inflammatory and analgesic agents." Zeitschrift für Naturforschung B 70, no. 7 (July 1, 2015): 519–26. http://dx.doi.org/10.1515/znb-2015-0009.

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AbstractSearching for new anti-inflammatory and analgesic agents, we have prepared a series of novel pyrazoles containing benzofuran and trifluoromethyl moieties. The pyrazole derivatives have been synthesized via two routes starting from 5-(3-(trifluoromethyl)phenyl azo) salicylaldehyde. The first route involved the synthesis of 2-acetylbenzofuran and then treatment with aldehydes to afford the corresponding chalcones. The cyclization of the latter chalcones with hydrazine hydrate led to the formation of new pyrazoline derivatives. The second route involved the synthesis of benzofuran-2-carbohydrazide and then treatment with formylpyrazoles, chalcones and ketene dithioacetal derivatives to afford the corresponding pyrazole derivatives. Some of the synthesized compounds exhibited anti-inflammatory and analgesic activities.

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23

Çetin, Adnan, Ishak Bildirici, and Selçuk Gümüş. "Novel Pyrazole Derivatives Having Mono/Di Chiral Centered Group as Organocatalyst for Henry Reaction." Macedonian Journal of Chemistry and Chemical Engineering 39, no. 1 (June 9, 2020): 17. http://dx.doi.org/10.20450/mjcce.2020.1954.

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The chiral substituted pyrazole-3-carboxamides (4a-c), pyrazole-3-carboxylates (5a-c), pyrazole-3-thioureides (7a-c) and pyrazole-3,4-dicarboxamides (10a-c) were prepared via the pyrazolo-3-chlorocarbonyl 2, pyrazolo-3,4-dicarboxy methyl ester 3 with pyrazole-3-isothiocyanate 6 with different (R)-chiral amino alcohols. All of the synthesized chiral compounds binding a pyrazole skeleton were investigated as organocatalysts for asymmetric aldol reactions between nitromethane and p-nitrobenzaldehyde in the presence of CuCl. Enantiomeric excesses and the reaction yields were found to be appropriate values. Furthermore, the best organocatalyst applied in this study was identified after careful optimization of conditions. Lastly, all of the novel compounds were subjected to computational analysis at the B3LYP/6-31++G(d,p) level of theory to obtain information about their structural and electronic properties.

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24

Hosny, Mona A., Yasser H. Zaki, Wafaa A. Mokbel, and Abdou O. Abdelhamid. "Synthesis, Characterization, Antimicrobial Activity and Anticancer of Some New Pyrazolo[1,5-a]pyrimidines and Pyrazolo[5,1-c]1,2,4-triazines." Medicinal Chemistry 16, no. 6 (September 7, 2020): 750–60. http://dx.doi.org/10.2174/1573406415666190620144404.

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Background: Pyrazole and its derivatives are known to exhibit significant biological and pharmacological activities such as anticancer, anti-inflammatory, antioxidant, antibacterial, analgesic, antiviral, antimicrobial, antifungal, anti-glycemic, antiamoebic, and antidepressive. Considering the immense biological properties, pyrazole is one of the most widely studied nitrogen- containing heterocyclic nuclei. Fused pyrazole derivatives are composed of the pyrazole nucleus attached to other heterocyclic moieties. Objective: The objective of this article is the synthesis of some new pyrazolo[1,5-a]pyrimidine and pyrazolo[5,1-c]1,2,4-triazine derivatives with potential anticancer and antimicrobial activities. Methods: The in vitro growth inhibitory rates (%) and inhibitory growth activity (as measured by IC50) of the newly synthesized compounds were determined against the MCF-7 human breast carcinoma cell line in comparison with the well-known anticancer drug doxorubicin as the standard, using the MTT viability assay. The data generated were used to plot a dose-response curve from which the concentration (μM) of tested compounds required to kill 50% of the cell population (IC50) was determined. Cytotoxic activity was expressed as the mean IC50 of three independent experiments. The difference between inhibitory activities of all compounds with different concentrations was statistically significant p < 0.001. All compounds were structurally characterized by different spectroscopic techniques EI-MS, 1H-NMR, and 13C-NMR, and evaluated for their anticancer and antimicrobial activities (antibacterial and antifungal). Results: Several pyrazolo[1,5-a]pyrimidine derivatives were synthesized from the reaction of 2-(4- (5-amino-1H-pyrazol-3-yl)phenyl)-1H-indene-1,3(2H)-dione with the appropriate active methylene compounds in boiling ethanol. Also, pyrazolo[5,1-c]triazines were obtained through the reaction of 2-(4-(5-(chlorodiazenyl)-1H-pyrazol-3-yl)phenyl)-1H-indene-1,3(2H)-dione with various active methylene compounds in ethanol containing sodium acetate at 0-5 °C. The structures of the newly synthesized compounds were elucidated on the basis of elemental analysis, spectral data, and alternative synthetic routes whenever possible. The newly synthesized compounds were evaluated for their antitumor activity against a breast cancer cell line (MCF-7) and a human colon cancer cell line (HCT-116). The results revealed that the tested compounds showed high variation in the inhibitory growth rates and activities against the tested tumor cell lines. All newly synthesized compounds screen towards microorganisms e.g. Gram-negative bacteria, Gram-positive bacteria, and Fungi. Conclusions: 2-(4-(5-Amino-1H-pyrazol-3-yl)phenyl)isoindoline-1,3-dione proved to be a useful precursor for the synthesis of various pyrazolo[1,5-a]pyrimidine and pyrazolo[5,1-c]-1,2,4- triazines. The structures of the newly synthesized compounds were confirmed by spectral data and elemental analyses. The newly synthesized compounds were tested in vitro against the MCF-7, HCT-116 human cancer cell line and compared with doxorubicin as the standard, using the MTT viability assay. Most of the tested compounds were found to have moderate to high anticancer activity.

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25

Abeed, Ahmed A. O., Talaat I. El-Emary, and Mohamed S. K. Youssef. "A Facile Synthesis and Reactions of Some Novel Pyrazole-based Heterocycles." Current Organic Synthesis 16, no. 3 (June 17, 2019): 405–12. http://dx.doi.org/10.2174/1570179416666181210160908.

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Aim and Objective: This work presents the synthetic capability and the exploitation of 1,3-diphenyl- 1H-pyrazole-4-carboxladehyde 1 and 5-diphenyl pyrazolyl-2-pyrazoline analogue 8 to serve as excellent precursors for the synthesis of substituted indol-2,3-dione, trizolo[3,4-a]benzazoles, thiazolo[2,3- a]benzimidazole-3-one, substituted 2-pyrazoline and pyrazole-substituted-pyrazolines using various reagents. Materials and Methods: Using chemicals from Aldrich, Fluka, or Merck, and pure solvents, we apply the synthetic procedures for the synthesis of novel heterocycles. The melting points of these compounds were determined using APP. Digital ST 15 melting point apparatus. SP3-100 spectrophotometer recorded FT-IR spectra (KBr) (cm-1). NMR spectra (δ, ppm) were recorded on 400 MHz AVANCE-III High-Performance FT-NMR Spectrometer BRUCKER (Switzerland) and some 1H NMR spectra were recorded on Varian EM-360L NMR Spectrophotometer (90 MHz) (USA) in CDCl3 or DMSO-d6 as a solvent. Elemental analyses were carried out at a Vario EL C, H, N, and S Analyzer. Bromine was determined using direct titration method after carius combustion. Results: The structures of the compounds were confirmed by IR, 1H NMR, 13C NMR, and elemental analyses. Conclusion: 1,3-Diphenyl-1H-pyrazole-4-carboxladehyde 1 and 2-pyrazoline derivative 9 confirmed their importance in the synthetic organic chemistry. Depending on the formyl group of aldehyde 1 and active methylene of pyrazoline 8, we synthesized new series of heterocycles; indol-2,3-dione, trizolo[3,4-a]benzazole, thiazolo[2,3-a]benzimidazole-3-one and pyrazolyl-pyrazoline derivatives expecting their pharmacological applications. The targeted compounds were substantiated from its spectral data.

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Albar, Hassan A. "1,3-Dipolar Cycloaddition of Four Hydrazonoyl Chlorides to β-Diketones and α,β-Unsaturated Ketones." Journal of Chemical Research 23, no. 3 (March 1999): 182–83. http://dx.doi.org/10.1177/174751989902300306.

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The 1,3-dipolar cycloaddition of four hydrazonoyl chloride derivatives with the sodium salt of unsymmetrical β-diketones (benzoylacetone) offers a versatile method for the regioselective synthesis of 2 H-pyrazoles in a similar fashion to the cycloaddition of the nitrilimides with α,β-unsaturated ketones and esters; the structures of the prepared isomeric pyrazole and pyrazoline derivatives are established by spectroscopic and chemical methods.

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Deeb, Ali, Medhat El-Mobayed, Abdel Naby Essawy, Adel Abd El-Hamid, and Atef Mohamid Abd El-Hamid. "Heterocyclic synthesis from 3-amino-4-cyanopyrazole." Collection of Czechoslovak Chemical Communications 55, no. 3 (1990): 728–33. http://dx.doi.org/10.1135/cccc19900728.

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3-Amino-4-cyanopyrazole I reacts with hydroxylamine and with hydrazine to yield 1H,6H-3-aminopyrazolo[3,4-c]pyrazole (III and IV). Diazotized IV couples with 2-naphthol to give the arylazo derivative VI which cyclizes to 9H-naphthol[2,1-e]pyrazolo[3',4':3,4]pyrazolo[5,1-c]-[1,2,4]triazine VII by means of acetic acid. The pyrazol-5-ylthiourea obtained from I and phenyl isothiocyanate undergoes base-catalyzed cyclization to give pyrazolo[3,4-d]pyrimidinethione derivative IX. Compound I reacts with cyclohexane in the presence of zinc chloride to give the tetrahydropyrazolo[3,4-b]quinoline derivative XI. The reaction of I with pyridine 1-oxide affords 4H,5H-pyrazolo[5',1':2,3] [1,2,4]triazolo[1,5-a]pyridine-3-carbonitrile XII.

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28

Roman, Gheorghe. "2-Naphthol-pyrazole conjugates as substrates in the Mannich reaction." Zeitschrift für Naturforschung B 73, no. 5 (May 24, 2018): 275–80. http://dx.doi.org/10.1515/znb-2017-0209.

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AbstractSeveral novel 2-naphthol-pyrazole conjugates have been synthesized through the O-alkylation of 1-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]naphthalen-2-ol with methyl iodide, benzyl chloride, methyl bromoacetate and N-benzyl-2-bromoacetamide. The aminomethylation of these 2-naphthol-pyrazole conjugates has been examined employing the classical conditions for the Mannich reaction, and also by using N,N-dimethylmethyleneiminium chloride as preformed aminomethylating reagent. In both situations, aminomethylation of these substrates occurred at C-4 of the pyrazole ring. The bifunctional substrate 1-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]naphthalen-2-ol has been chemoselectively aminomethylated in the pyrazole ring using the same preformed aminomethylating reagent.

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29

Edrees, Mastoura M. "Synthesis of 4-hydrazinopyrazolo[3,4-d]pyrimidines and their Reactions with Carbonyl Compounds." Journal of Chemical Research 37, no. 1 (January 2013): 6–10. http://dx.doi.org/10.3184/174751912x13543818811749.

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Synthesis of a new 4-hydrazinopyrazolo[3,4- d]pyrimidine was achieved via heating (4,6-dithioxo-1 H-pyrazolo[3,4- d] pyrimidin-3-yl)acetonitrile with hydrazine hydrate. Reactions of the latter product with thiophene-2-carbaldehyde and ethyl hydrazonoacetoacetate analogues afforded the corresponding hydrazone and pyrazole derivatives, respectively. Similarly, condensation of 2-[6-(benzylsulfanyl)-4-hydrazino-1 H-pyrazolo[3,4- d]pyrimidin-3-yl]acetonitrile with thiophene-2-carbaldehyde and ethyl hydrazonoacetoacetate analogues gave the respective hydrazone and pyrazolone derivatives. Alkylation reactions of 2-[4,6-bis(benzylsulfanyl)-1 H-pyrazolo[3,4- d]pyrimidin-3-yl]acetonitrile with arylamines gave the respective 4-( N-arylamino)-6-benzylsulfanylpyrazolo[3,4- d]pyrimidine derivatives.

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30

Lamie, Phoebe F. "Synthesis and Antimicrobial Activity of some Novel Isoindoline-1,3-Dione Derivatives." JOURNAL OF ADVANCES IN CHEMISTRY 8, no. 2 (March 2, 2008): 1660–66. http://dx.doi.org/10.24297/jac.v8i2.5570.

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New phthalimido derivatives incorporated with chalcone, pyrazole, pyrazoline, and pyrimidine moieties were synthesized and evaluated for their antimicrobial activities against bacterial and fungal strains. 2-{4-[1-Acetyl-5-(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-3-yl]phenyl} isoindoline-1,3-dione (7) showed broad spectrum antibacterial activity against both G+ and G- bacteria. While, (E)-2-{4-[3-(4-chlorophenyl)acryloyl]phenyl}isoindoline-1,3-dione (4b) showed promising antifungal activity.

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Lynch, Brian Maurice, Misbahul Ain Khan, Huk Chia Teo, and Francisco Pedrotti. "Pyrazolo[3,4-b]pyridines: Syntheses, reactions, and nuclear magnetic resonance spectra." Canadian Journal of Chemistry 66, no. 3 (March 1, 1988): 420–28. http://dx.doi.org/10.1139/v88-074.

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Efficient syntheses of approximately 70 simple substituted representatives of pyrazolo[3,4-b]pyridine 1 are reported from the following: (a) suitably substituted pyridines onto which a pyrazole ring is annelated, and (b) appropriately substituted pyrazoles onto which a pyridine ring is annelated. Selected examples of electrophilic, nucleophilic, and homolytic substitution reactions and group transformations are described, providing regiosynthetic paths to useful intermediate species. Some systematic aspects of substituent chemical shift influences in the 1H and 13C nuclear magnetic resonance spectra, aiding in structural assignments, are illustrated.

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Mcfadden, HG, and JL Huppatz. "Synthesis of (Pyrazol-4-yl)alkanones and Alkylpyrazole-4-Carbonitriles." Australian Journal of Chemistry 44, no. 9 (1991): 1263. http://dx.doi.org/10.1071/ch9911263.

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1-(5-Aminopyrazol-4-yl)alkan-1-ones and 5-alkylpyrazole-4-carbonitriles were obtained by reaction of 2-(1-ethoxyalkylidene)-3-oxoalkanenitriles (acrylonitriles) with hydrazines. The ratios of the various pyrazole products depended on the solvent used, and on the nature of the substituents on both the acrylonitrile and hydrazine reactants. In general, formation of pyrazole-4-carbonitriles was favoured by the use of acetic acid whereas use of ethanol favoured the formation of 1-(pyrazol-4-yl)alkan-1-ones. The use of 3-ethylacrylonitrile gave predominantly 3-ethylpyrazole-4-carbonitriles whereas acrylonitriles unsubstituted in the 3-position gave mainly 1-(pyrazol-4-yl)alkan-1-ones. The use of hydrazine gave exclusively pyrazole-4-carbonitriles irrespective of other factors, whereas use of methyl- and phenyl- hydrazines gave mixtures of varying composition depending on the acrylonitrile 3-substituent and the solvent. This synthesis provides a convenient route using mild conditions to novel pyrazole-4-carbonitriles and 1-(pyrazol-4-yl)alkan-1-ones which may have interesting biological properties.

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Qiao, Li, Peng-Peng Cai, Zhong-Hua Shen, Hong-Ke Wu, Cheng-Xia Tan, Jian-Quan Weng, and Xing-Hai Liu. "Crystal structure and molecular docking studies of new pyrazole-4-carboxamides." Heterocyclic Communications 25, no. 1 (May 11, 2019): 66–72. http://dx.doi.org/10.1515/hc-2019-0012.

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AbstractTwo pyrazol-4-carboxamides, 3-(difluoromethyl)-N-(mesitylcarbamoyl)-1-methyl-1H-pyrazole-4-carboxa-mide (7a) and 3-(difluoromethyl)-N-((3,5-dimethylphenyl) carbamoyl)-1-methyl-1H-pyrazole-4-carboxamide (7b) were synthesized and their structures were confirmed by the aid of 1H NMR and HRMS analyses. The structure of the pyrazole-4-carboxamide, 7a was also determined by X-ray diffraction. The preliminary activity results demonstrate that these two compounds exhibit good inhibitory activity against Botrytis cinerea. Further docking results indicated that the key active group is difluoromethyl pyrazole moiety.

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Camoutsis, Charalambos, Sotirios Nicolaropoulos, and Panayotis Catsoulacos. "Steroidal pyrazoline and pyrazole." Journal of Chemical & Engineering Data 32, no. 4 (October 1987): 478–79. http://dx.doi.org/10.1021/je00050a030.

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Jasril, Jasril, Neni Frimayanti, Yuana Nurulita, Adel Zamri, Ihsan Ikhtiarudin, and Guntur Guntur. "5-(4-Fluorophenyl)-3-(naphthalen-1-yl)-1-phenyl-1H-pyrazole." Molbank 2021, no. 1 (March 10, 2021): M1197. http://dx.doi.org/10.3390/m1197.

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A new fluorinated pyrazole, 5-(4-fluorophenyl)-3-(naphthalen-1-yl)-1-phenyl-1H-pyrazole was successfully synthesized via a two-step reaction. Firstly, the synthesis of pyrazoline was performed via one-pot three-component reaction under microwave irradiation. Secondly, the synthesis of pyrazole was performed via oxidative aromatization of pyrazoline under conventional heating. The structure of the synthesized compound was confirmed by spectroscopic analysis, including FT-IR, HR-MS, 1D and 2D NMR analysis. Then, molecular docking study showed that the binding affinity of the synthesized compound to human estrogen alpha receptor (ERα) was close to 4-OHT as a native ligand.

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Meta, Elda, Chiara Brullo, Michele Tonelli, Scott G. Franzblau, Yuehong Wang, Rui Ma, Wan Baojie, Beatrice S. Orena, Maria R. Pasca, and Olga Bruno. "Pyrazole and imidazo[1,2-b]pyrazole Derivatives as New Potential Antituberculosis Agents." Medicinal Chemistry 15, no. 1 (January 7, 2019): 17–27. http://dx.doi.org/10.2174/1573406414666180524084023.

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Background: We screened a large library of differently decorated imidazo-pyrazole and pyrazole derivatives as possible new antitubercular agents and this preliminary screening showed that many compounds are able to totally inhibit Mycobacterium growth (>90 %). Among the most active compounds, we selected some new possible hits based on their similarities and, at the same time, on their novelty with respect to the pipeline drugs. Methods: In order to increase the potency and obtain more information about structure-activity relationship (SAR), we designed and synthesized three new series of compounds (2a–e, 3a–e, and 4a–l). Conclusion: Performed tests confirmed that both new pyrazoles and imidazo-pyrazoles could represent a new starting point to obtain more potent compounds and further work is now underway to identify the protein targets of this new class of anti-TB agents.

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Kumar, Harish, Kushal Kumar Bansal, and Anju Goyal. "Synthetic Methods and Antimicrobial Perspective of Pyrazole Derivatives: An Insight." Anti-Infective Agents 18, no. 3 (September 11, 2020): 207–23. http://dx.doi.org/10.2174/2211352517666191022103831.

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Background: Due to newly emerging microbial infections and the development of resistance against cutting-edge therapeutics, innovative and robust medicinal agents are required. Small ring heterocycles, such as pyrazole and its derivatives have been acknowledged to possess myriad biological properties and the presence of pyrazole in clinics like celecoxib, phenylbutazone (anti-inflammatory), CDPPB (antipsychotic), rimonabant (anti-obesity), antipyrine, difenamizole (analgesic), fipronil (broad-spectrum insecticidal), betazole (H2-receptor agonist) and fezolamide (antidepressant) drugs has proven the pharmacological perspective of pyrazole nucleus. Objectives: The current review paper aimed at a recent update made on novel methodologies adopted in the synthesis of pyrazole derivatives with the emphasis on antibacterial (DNA gyrase inhibition) and antifungal activities. Methods: Pyrazole is one of the major tools to be investigated in drug design and discovery. Many studies have been reported by researchers that have claimed the significant biological potential of these derivatives. However, numerous studies on pyrazoles compounds shown to exhibit potential antifungal and antibacterial activities, the focus has also been made on DNA gyrase inhibition. Additionally, some important patents granted to this heterocyclic nucleus related to antimicrobial potential are also addressed appropriately. Results: DNA gyrase is a promising biotarget yet to be explored against a number of medicinal agents. The present work provides valuable insight into synthetic methods and antibacterials/antifungal significance of pyrazoles in general as well as new inhibitors of DNA gyrase in particular. Conclusion: The manuscript constitutes a valuable reference which advocates candidature of pyrazoles as a potential therapeutic alternative as antibacterial and antifungal agent.

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Santos, Nádia E., Ana R. F. Carreira, Vera L. M. Silva, and Susana Santos Braga. "Natural and Biomimetic Antitumor Pyrazoles, A Perspective." Molecules 25, no. 6 (March 17, 2020): 1364. http://dx.doi.org/10.3390/molecules25061364.

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The present review presents an overview of antitumor pyrazoles of natural or bioinspired origins. Pyrazole compounds are relatively rare in nature, the first ones having been reported in 1966 and being essentially used as somniferous drugs. Cytotoxic pyrazoles of natural sources were first isolated in 1969, and a few others have been reported since then, most of them in the last decade. This paper presents a perspective on the current knowledge on antitumor natural pyrazoles, organized into two sections. The first focuses on the three known families of cytotoxic pyrazoles that were directly isolated from plants, for which the knowledge of the medicinal properties is in its infancy. The second section describes pyrazole derivatives of natural products, discussing their structure–activity relationships.

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Ardiansah, Bayu. "RECENT REPORTS ON PYRAZOLE-BASED BIOACTIVE COMPOUNDS AS CANDIDATE FOR ANTICANCER AGENTS." Asian Journal of Pharmaceutical and Clinical Research 10, no. 12 (December 1, 2017): 45. http://dx.doi.org/10.22159/ajpcr.2017.v10i12.22065.

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Pyrazole is a five-membered heterocyclic compound containing two nitrogen atoms. Due to its biological significance, design of novel pyrazole derivatives has become an interesting research area. We report the current progress in the development of anticancer agents containing pyrazole ring covering the time span of the past few years (2013–2016). The presence of this nucleus is accompanied with some side chains, functional groups, or in combination with other nucleus such as thiazole, thiourea, glucosamine, naphthalimide, and benzofuran. Several biologically active pyrazoles synthesized by numerous researchers across the world are summarized in this paper.

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Dodiya, Dipti, Amit Trivedi, Samir Jarsania, Shailesh Vaghasia, and Viresh Shah. "Characterization and biological evaluation of some novel pyrazolo[3',4':4,5]thieno[2,3-d]pyrimidin-8-ones synthesized via the Gewald reaction." Journal of the Serbian Chemical Society 73, no. 7 (2008): 683–90. http://dx.doi.org/10.2298/jsc0807683d.

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The synthesis of substituted pyrazolo[3',4':4,5]thieno[2,3-d]pyrimidin-8-ones (IIIa-j) from 5-amino-3-methyl-1H-thieno[3,2-c]pyrazole-6-carbonitrile (II) is described. The key compound II was synthesized from (5-methyl- -2,4-dihydro-3H-pyrazol-3-ylidene)malononitrile I via the Gewald reaction. The synthesis of the title compounds IIIa-j was accomplished by condensation of II with different aromatic aldehydes. The newly synthesized heterocyles were characterized by elemental analysis, IR, 1H-NMR, 13C-NMR and mass spectroscopic investigation. All the newly synthesized compounds were evaluated for antimicrobial activity against a variety of bacterial strains. .

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41

Bharathi, R. "In vitro and molecular docking studies of an antiinflammatory scaffold with human peroxiredoxin 5 and tyrosine kinase receptor." Bioinformation 16, no. 11 (November 30, 2020): 929–36. http://dx.doi.org/10.6026/97320630016929.

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A new series of 4-(3-(2-amino-3,5-dibromophenyl)-1-(4-substitutedbenzoyl)-4,5-dihydro-1H-pyrazol-5-yl)benzonitrile (4a-h) compounds were synthesized and evaluated for in-vitro anti-inflammatory activities. The spectral (IR, NMR) and elemental analyses data of the product indicated the formation of new pyrazoles 4a-h. Compound 4e exhibited potent anti-inflammatory property with 85.45 % inhibitions. This value was compared with standard diclofenac sodium. This data is explained using molecular docking analysis of receptor-ligand binding. These results demonstrated that pyrazole derivatives are potential inhibitors of Human Peroxiredoxin 5 and Tyrosine kinase receptor in the treatment of inflammation related illness.

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42

Dotsenko, Victor V., Aminat M. Semenova, and Nicolai A. Aksenov. "New Reactions of 5-Amino-3-(Cyanomethyl)-1H-Pyrazole-4-Carbonitrile." Chemistry Proceedings 3, no. 1 (November 14, 2020): 23. http://dx.doi.org/10.3390/ecsoc-24-08398.

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5-Amino-3-(cyanomethyl)-1H-pyrazole-4-carbonitrile, prepared by reaction of malononitrile dimer with hydrazine, smoothly reacts with chloroacetyl chloride to form 2-chloro-N-(4-cyano-3-(cyanomethyl)-1H-pyrazol-5-yl)acetamide in good yield. The latter easily reacts with 3-cyanopyridine-2-thiolates to give hybrid molecules bearing nicotinonitrile and pyrazole units.

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Radini, Ibrahim. "Design, Synthesis, and Antimicrobial Evaluation of Novel Pyrazoles and Pyrazolyl 1,3,4-Thiadiazine Derivatives." Molecules 23, no. 9 (August 21, 2018): 2092. http://dx.doi.org/10.3390/molecules23092092.

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A novel series of pyrazolyl 1,3,4-thiadiazines 5a–c, 8a–c, 12, 15a–c, 17a–c, and 20 was prepared from the reaction of pyrazole-1-carbothiohydrazide 1a,b with 2-oxo-N′-arylpropanehydrazonoyl chloride, 2-chloro-2-(2-arylhydrazono)acetate, and 3-bromoacetylcoumarin. Moreover, the regioselective reaction of 5-pyrazolone-1-carbothiohydrazide 1a with 4-substituted diazonium salts and 4-(dimethylamino)benzaldehyde gave the corresponding hydrazones 21a–c and 22. The newly prepared compounds were characterized by spectroscopy and elemental analysis. Many new synthesized compounds showed considerable antimicrobial activity against tested microorganisms. Hydrazones 21a–c and 22 showed remarkable antibacterial and antifungal activities. 4-(2-(p-tolyl)hydrazineylidene)-pyrazole-1-carbothiohydrazide 21a displayed the highest antibacterial and antifungal activities with minimum inhibitory concentration (MIC) values lower than standard drugs chloramphenicol and clotrimazole, in the range of 62.5–125 and 2.9–7.8 µg/mL, respectively.

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44

Deepa, M., V. Harinadha Babu, R. Parameshwar, and B. Madhava Reddy. "Synthesis of 3-(1, 3-Diphenyl-1H-pyrazol-4-yl) Propanoic Acids Using Diimide Reduction." E-Journal of Chemistry 9, no. 1 (2012): 420–24. http://dx.doi.org/10.1155/2012/481682.

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Pyrazole-1H-4-yl-acrylic acids (3a-j) were prepared from pyrazole-1H-4-carbaldehydes which in turn were prepared by the Vilsmeier-Haack reaction of phenyl hydrazone derivatives (1a-j). The reaction of pyrazole-1H-4-yl-acrylic acids to 3-(1, 3-diphenyl-1H-pyrazol-4-yl) propanoic acids (4a-j) was carried out using Pd-charcoal and diimide methods and % yields were compared. Though the yields may be slightly less in diimide method, the method was found to be economical, highly effective with simple operating procedure.

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Becerra, Diana, Hugo Rojas, and Juan-Carlos Castillo. "3-(tert-Butyl)-N-(4-methoxybenzyl)-1-methyl-1H-pyrazol-5-amine." Molbank 2021, no. 1 (March 10, 2021): M1196. http://dx.doi.org/10.3390/m1196.

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We reported an efficient one-pot two-step synthesis of 3-(tert-butyl)-N-(4-methoxybenzyl)-1-methyl-1H-pyrazol-5-amine 3 in good yield by a solvent-free condensation/reduction reaction sequence starting from 3-(tert-butyl)-1-methyl-1H-pyrazol-5-amine 1 and p-methoxybenzaldehyde 2. The one-pot reductive amination proceeded by the formation in situ of the N-(5-pyrazolyl)imine 4 as key synthetic intermediate of other valuable pyrazole derivatives. This methodology is distinguished by its operational easiness, short reaction time, isolation and purification of the aldimine intermediate is not required. The structure of the synthesized N-heterocyclic amine 3 was fully characterized by FTIR-ATR, 1D and 2D NMR experiments, EIMS, and elemental analysis.

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Erdem, Ahmet, Hasan Genc, Nejdet Sen, Rafet Kilincarslan, and Emin Erdem. "The Synthesis and Reactions of Novel Pyrazole Derivatives by 4-phenylcarbonyl-5-phenyl-2,3-dihydro-2,3-furandione Reacted with Some Hydrazones." Revista de Chimie 68, no. 1 (February 15, 2017): 143–46. http://dx.doi.org/10.37358/rc.17.1.5407.

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We report some novel pyrazole derivatives taking 4-phenylcarbonyl-5-phenyl-2,3-dihydro-2,3-furandione, 1. For this, 4-phenylcarbonyl-5-phenyl-2,3-dihydro-2,3-furandione, 1 was reacted with benzaldehyde(2- or 4-fluorophenyl)hydrazone to give 4-benzoyl-1-(2- or 4-fluorophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid 2a,b. Pyrazol derivative containing 2-fluorophenyl group 2a was converted into carboxylic chloride derivative 3a by thionyl chloride and then the compound 4a was obtained from reaction ammonia with compound 3a. In the next step, 4-benzoyl-1-(2-fluorophenyl)-5-phenyl-1H-pyrazole-3-carboxylic acid 2a was reacted with MeOH/H2SO4, EtOH/H2SO4, 2-nitrophenylhydrazine and 3-nitrophenylydrazine to give 5a,b and 6a,b pyrazol derivatives, respectively. The structures regarding all compounds synthesized were determined by the IR, NMR and elemental analysis method.

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Abdelhamid, Abdou O., Zeineb H. Ismail, and Anhar Abdel-Aziem. "Reactions with Hydrazonoyl Halides 601: Synthesis of Thieno[2′,3′:4,5] Pyrimidino[1,2-b][1,2,4,5]tetrazines, [1]benzothieno[2′,3′:4,5]pyrimidino [1,2-b][1,2,4,5]tetrazines, Pyrazolo[3′,4′:4,5]pyrimidino[1,2-b] [1,2,4,5]tetrazines and Pyrazolo[3,4-d]pyridazines." Journal of Chemical Research 2007, no. 10 (October 2007): 609–16. http://dx.doi.org/10.3184/030823407x256118.

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Thieno[2′,3′:4,5]pyrimidino[1,2- b][1,2,4,5]tetrazine, [1]benzothieno-[2′,3′:4,5]pyrimidino[1,2- b][1,2,4,5]tetrazine, pyrazolo [3′,4′:4,5]pyrimidino[1,2- b][1,2,4,5]tetrazine, triazolo[4,3- a]pyrimidin-5(1 H)-one, 1-{[2-(1-benzofuran-2-yl)-5-phenyl-4,5-dihydro-1 H-pyrazol-1-yl]-4-substituted-1,3-thiazol-5-yl}-2-phenyldiazene, 3-acyl-4-(1-benzofuran-2-ylcarbonyl) pyrazole and pyrazolo[3,4- d]pyridazine derivatives could be obtained via reactions of hydrazonoyl halides with the appropriate pyrimidine-2-thione, 3-amino-5,6-dimethyl-2-sulfanylthieno[2,3- d]pyrimidin-4(3 H)-one, 5-amino-6-mercapto-1-phenyl-1,5-dihydropyrazolo[3,4- d]pyrimidin-4-one and 1-(benzofuran-2-yl)-3-(dimethylamino)prop-2-en-1-one. Structures of the products have been determined by elemental analyses, spectral data studies and alternative synthesis whenever possible.

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48

Archana, Sreeramapura D., Channappa N. Kavitha, Hemmige S. Yathirajan, Sabine Foro, and Christopher Glidewell. "Two 3-amino-1H-pyrazol-2-ium salts containing organic anions, and an orthorhombic polymorph of 3-amino-1H-pyrazol-2-ium nitrate." Acta Crystallographica Section E Crystallographic Communications 77, no. 1 (January 1, 2021): 34–41. http://dx.doi.org/10.1107/s2056989020015959.

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Co-crystallization from methanol of 3-amino-1H-pyrazole with 3,5-dinitrobenzoic acid produces 3-amino-1H-pyrazol-2-ium 3,5-dinitrobenzoate monohydrate, C3H6N3 +·C7H3N2O6 −·H2O, (I), while similar co-crystallization of this pyrazole with an equimolar quantity of fumaric acid produces bis(3-amino-1H-pyrazol-2-ium) fumarate–fumaric acid (1/1), 2C3H6N3 +·C4H2O4 2−·C4H4O4, (II). The reaction of 3-amino-1H-pyrazole with a dilute solution of nitric acid in methanol yields a second, orthorhombic polymorph of 3-amino-1H-pyrazol-2-ium nitrate, C3H6N3 +·NO3 −, (III). In each of (I)–(III), the bond distances in the cation provide evidence for extensive delocalization of the positive charge. In each of (I) and (II), an extensive series of O—H...O and N—H...O hydrogen bonds links the components into complex sheets, while in the structure of (III), the ions are linked by multiple N—H...O hydrogen bonds into a three-dimensional arrangement. Comparisons are made with the structures of some related compounds.

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Cetin, Adnan, and Havva Kurt. "Synthesis, Antibacterial Activity and Molecular Docking Studies of New Pyrazole Derivatives." Letters in Drug Design & Discovery 17, no. 6 (June 29, 2020): 745–56. http://dx.doi.org/10.2174/1570180816666190905155510.

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Background: The pyrazole structure is an important heterocyclic structure and plays critical roles in agriculture, industrial and medicine. Furthermore, compounds containing pyrazole are known to exhibit various biological properties such as antibacterial, antifungal, anticancer, antiinflammatory, antidepressant, antipyretic, antiviral, anti-tubercular and anti-HIV activities. Because of these properties, pyrazole molecules have become a very popular topic for organic chemists. Methods: A series newly substituted pyrazole molecules were synthesized and characterized. Their antimicrobial activities were investigated by disk diffusion method against some gram positive bacteria and gram negative bacteria. Results: The present results indicated that the some test compounds were active in a broad spectrum against important human pathogenic microorganisms. The substituted pyrazoles including carbazone (7a, b) and thiazolidine (8a, b) showed a wide variety of biological activities. The results showed that synthesized pyrazole, compounds 7b and 8b are highly active and more potent in both biological and molecular docking simulation studies. Conclusion: The synthesized pyrazole molecules showed moderate antibacterial activities against the tested microorganism compared to antibiotic drug. Some test compounds (7b and 8b) might be used as new antibacterial agents.

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El-Naggar, Mohamed, Amira S. Abd El-All, Shweekar I. A. El-Naem, Mohamed M. Abdalla, and Huda R. M. Rashdan. "New Potent 5α- Reductase and Aromatase Inhibitors Derived from 1,2,3-Triazole Derivative." Molecules 25, no. 3 (February 5, 2020): 672. http://dx.doi.org/10.3390/molecules25030672.

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This work describes the utility of pyrazole-4-carbaldehyde 1 as starting material for the synthesis of a novel potent series of 5α-reductase and aromatase inhibitors derived from 1,2,3-triazole derivative. Condensation of 1 with active methylene and different amino pyrazoles produced the respective Schiff bases 2–4, 8 and 9. On the other hand, 1 was reacted with ethyl cyanoacetate and thiourea in one-pot reaction to afford the pyrazolo-6- thioxopyridin-2-[3H]-one (10). Moreover, α–β unsaturated chalcone derivative 11 was prepared via the reaction of compound 1 with P-methoxy acetophenone, which in turn reacted with each of ethyl cyanoacetate, malononitrile, hydrazine hydrate, and thiosemicarbazide to afford the corresponding pyridine and pyrazole derivatives 13, 14, 17, and 20. The structure of newly synthesized compounds was characterized by analytical and spectroscopic data (IR, MS and NMR). All new compounds were evaluated against 5α-reductase and aromatase inhibitors and the results showed that many of these compounds inhibit 5α-reductase and aromatase activity; compound 13 was found to be the highest potency among the tested samples comparing with the reference drugs.

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Journal articles on the topic 'Pyrazole'

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