Artículos de revistas: "C]pyrazole"

1

Abaszadeh, Mehdi, Hassan Sheibani y 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, n.º 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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2

Sophy, Mohamed Ahmed Elian y Mohamed Ahmed Mahmoud Abdel Reheim. "Synthesis of Some New 1, 3, 4-Oxadiazole, Pyrazole, and Pyrimidine Bearing Thienopyrazole Moieties". Current Organic Synthesis 17, n.º 8 (28 de octubre de 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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3

Lindsay-Scott, Peter J. y Eloise Rivlin-Derrick. "Regiocontrolled Synthesis of 6,7-Dihydro-4H-pyrazolo[5,1-c][1,4]oxazines". Synthesis 52, n.º 01 (8 de octubre de 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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4

Gerster, Holger, Michael Keim y Gerhard Maas. "Cycloaddition reactions of acetylenic iminium salts and diazoacetates leading to pyrazole iminium salts". Zeitschrift für Naturforschung B 74, n.º 4 (24 de abril de 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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5

Bertolasi, Valerio, Paola Gilli, Valeria Ferretti, Gastone Gilli y Cristina Fernàndez-Castaño. "Self-assembly of NH-pyrazoles via intermolecular N—H...N hydrogen bonds". Acta Crystallographica Section B Structural Science 55, n.º 6 (1 de diciembre de 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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6

Milišiūnaitė, Vaida, Rūta Paulavičiūtė, Eglė Arbačiauskienė, Vytas Martynaitis, Wolfgang Holzer y 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 (14 de marzo de 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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7

Thirunarayanan, Ganesamoorthy y 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 (octubre de 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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8

Lerner, Hans-Wolfram, Günter Margraf, Tonia Kretz, Olav Schiemann, Jan W. Bats, Gerd Dürner, Fabrizia Fabrizi de Biani, Piero Zanello, Michael Boltea y Matthias Wagner. "Redox Behaviour of Pyrazolyl-Substituted 1,4-Dihydroxyarenes: Formation of the Corresponding Semiquinones, Quinhydrones and Quinones". Zeitschrift für Naturforschung B 61, n.º 3 (1 de marzo de 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

Ramadan, El Sayed, Essam M. Sharshira, Ramadan I. El Sokkary y Noussa Morsy. "Synthesis and antimicrobial evaluation of some heterocyclic compounds from 3-aryl-1-phenyl-1H-pyrazole-4-carbaldehydes". Zeitschrift für Naturforschung B 73, n.º 6 (27 de junio de 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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10

Çetin, Adnan, Ishak Bildirici y Selçuk Gümüş. "Novel Pyrazole Derivatives Having Mono/Di Chiral Centered Group as Organocatalyst for Henry Reaction". Macedonian Journal of Chemistry and Chemical Engineering 39, n.º 1 (9 de junio de 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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11

Rizk, Sameh, Ismail M. Awheda y Fathi A. Smida. "Synthesis and DFT Study of Newly Schiff Base and Fused Heterocyclic Compounds as Antibacterial Agent". JOURNAL OF ADVANCES IN CHEMISTRY 16 (7 de noviembre de 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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Hosny, Mona A., Yasser H. Zaki, Wafaa A. Mokbel y 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, n.º 6 (7 de septiembre de 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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13

Deeb, Ali, Medhat El-Mobayed, Abdel Naby Essawy, Adel Abd El-Hamid y Atef Mohamid Abd El-Hamid. "Heterocyclic synthesis from 3-amino-4-cyanopyrazole". Collection of Czechoslovak Chemical Communications 55, n.º 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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14

Radini, Ibrahim. "Design, Synthesis, and Antimicrobial Evaluation of Novel Pyrazoles and Pyrazolyl 1,3,4-Thiadiazine Derivatives". Molecules 23, n.º 9 (21 de agosto de 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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15

IBRAHIM, M. K. A., A. H. H. ELGHANDOUR, G. S. M. ABDEL-SAYED y A. S. M. ABDEL FATTAH. "ChemInform Abstract: Synthesis of Pyrazoles and Fused Pyrazoles. Novel Synthesis of Pyrano[2,3-c]pyrazole, Thieno[2,3-c]pyrazole and Pyrazolo[3,4-b]pyridine Derivatives." ChemInform 29, n.º 27 (21 de junio de 2010): no. http://dx.doi.org/10.1002/chin.199827039.

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16

Roman, Gheorghe. "2-Naphthol-pyrazole conjugates as substrates in the Mannich reaction". Zeitschrift für Naturforschung B 73, n.º 5 (24 de mayo de 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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17

Kang, Eunsu, Hyun Tae Kim y Jung Min Joo. "Transition-metal-catalyzed C–H functionalization of pyrazoles". Organic & Biomolecular Chemistry 18, n.º 32 (2020): 6192–210. http://dx.doi.org/10.1039/d0ob01265c.

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Sabah, Rusul Saad, Zahraa S. Al-Garawi y Mahmoud N. Al-jibouri. "The utilities of pyrazolines encouraged synthesis of a new pyrazoline derivative via ring closure of chalcone, for optimistic neurodegenerative applications". Al-Mustansiriyah Journal of Science 33, n.º 1 (10 de marzo de 2022): 21–31. http://dx.doi.org/10.23851/mjs.v33i1.1067.

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Pyrazolines and their derivatives have been extensively studied as coordinated ligands of high potential applications in diverse chemical and biological systems. This work explores some methods of synthesis of pyrazolines, such as the preparation of pyrazole derivatives via chalcones. It also demonstrates that 2-pyrazoline complexes were biologically active and have had a range of clinical applications. Palladium (II) complex of pyrazole was active as antitumor when tested against murine mammary adenocarcinoma (LM3). Copper (II) and Cobalt (II) complex are biologically active in the living system as biomolecules or co factors. Based on these information, we tried here to synthesis a new 2-pyrazoline from (E)-3-(4-bromophenyl)-1-(pyridin-2-yl)prop-2-en-1-one. The newly synthesized pyrazoline was characterized using mass spectroscopy, nucleic magnetic resonance spectroscopy NMR and Fourier transform infrared spectroscopy FTIR. The characterization results showed that 2-pyrazoline has successfully synthesized. The microanalyses (C.H.N.S), GC-MS, H and 13C NMR and FT-IR spectra confirmed the formation of 2-pyrazoline ring with substitution at N1,C-3 and C-5 and the spin-spin coupling constants (J) for the multiple peaks at H NMR spectra pointed to the de shielded aromatic protons in α and β protons of the prepared chalcone. Interestingly, some new family of pyrazoles that have isosteres of Zonisamide have previously showed activity toward treating neuroglial disorders such as epilepsy and autism. Thus, our synthesized pyrazole could have the potency to moderate some neurodegenerative disorders. It could negatively interact with some neurotransmitters through hydrogen bonding and electrostatic interactions with the amino and carboxylic ends of the functional ends of the neurotransmitters. This promising trend by the promising candidate 2- pyrazoline should have further investigations.

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Razmienė, Beatričė, Eva Řezníčková, Vaida Dambrauskienė, Radek Ostruszka, Martin Kubala, Asta Žukauskaitė, Vladimír Kryštof, Algirdas Šačkus y Eglė Arbačiauskienė. "Synthesis and Antiproliferative Activity of 2,4,6,7-Tetrasubstituted-2H-pyrazolo[4,3-c]pyridines". Molecules 26, n.º 21 (8 de noviembre de 2021): 6747. http://dx.doi.org/10.3390/molecules26216747.

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A library of 2,4,6,7-tetrasubstituted-2H-pyrazolo[4,3-c]pyridines was prepared from easily accessible 1-phenyl-3-(2-phenylethynyl)-1H-pyrazole-4-carbaldehyde via an iodine-mediated electrophilic cyclization of intermediate 4-(azidomethyl)-1-phenyl-3-(phenylethynyl)-1H-pyrazoles to 7-iodo-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridines followed by Suzuki cross-couplings with various boronic acids and alkylation reactions. The compounds were evaluated for their antiproliferative activity against K562, MV4-11, and MCF-7 cancer cell lines. The most potent compounds displayed low micromolar GI50 values. 4-(2,6-Diphenyl-2H-pyrazolo[4,3-c]pyridin-7-yl)phenol proved to be the most active, induced poly(ADP-ribose) polymerase 1 (PARP-1) cleavage, activated the initiator enzyme of apoptotic cascade caspase 9, induced a fragmentation of microtubule-associated protein 1-light chain 3 (LC3), and reduced the expression levels of proliferating cell nuclear antigen (PCNA). The obtained results suggest a complex action of 4-(2,6-diphenyl-2H-pyrazolo[4,3-c]pyridin-7-yl)phenol that combines antiproliferative effects with the induction of cell death. Moreover, investigations of the fluorescence properties of the final compounds revealed 7-(4-methoxyphenyl)-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridine as the most potent pH indicator that enables both fluorescence intensity-based and ratiometric pH sensing.

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20

Abeed, Ahmed A. O., Talaat I. El-Emary y Mohamed S. K. Youssef. "A Facile Synthesis and Reactions of Some Novel Pyrazole-based Heterocycles". Current Organic Synthesis 16, n.º 3 (17 de junio de 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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21

Frampton, Christopher S., Michael W. Majchrzak y John Warkentin. "Sense of sequential 1,5-sigmatropic rearrangements of dimethyl-3,3-dialkyl-3H-pyrazole-4,5-dicarboxylates. Crystal and molecular structures of two dimethyl-4,5-dialkyl-1H-pyrazole-1,3-dicarboxylates". Canadian Journal of Chemistry 69, n.º 3 (1 de marzo de 1991): 373–78. http://dx.doi.org/10.1139/v91-057.

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3,3-Dialkyl-3H-pyrazole-4,5-dicarboxylic acid dimethyl esters (4), obtained by cycloaddition of R1R2C=N+=N− (R1 = R2 = CH3; R1 = CH3, R2 = CH2CH3) to CH3O2CC≡CCO2CH3, rearrange thermally by 1,5-sigmatropic alkyl shifts to both N and C. The latter rearrangement is followed by two successive 1,5-sigmatropic shifts of a methoxycarbonyl group. Final products of the threefold rearrangement were shown to be 4,5-dialkyl-1H-pyrazole-1,3-dicarboxylic acid dimethyl esters (6), rather than the isomeric 3,4-dialkyl-1H-pyrazole-1,5-dicarboxylic acid dimethyl esters (7), by means of single crystal X-ray diffraction. Those products therefore result from alkyl migration to C-4 of 4, followed by sequential migration of the methoxycarbonyl group, initially at C-4, to C-3 and then to N-2 of 4. In the initial alkyl migration step, ethyl migrates in preference to methyl, and in subsequent migration steps the methoxycarbonyl group migrates faster than the ethyl or methyl group. Crystals of 4-ethyl-5-methyl-1H-pyrazole-1,3-dicarboxylic acid dimethyl ester (6b) are monoclinic, of space group P21/n, with a = 7.907(1) Å, b = 11.087(2) Å, c = 13.199(3) Å, V = 1124.9(4) Å 3, Dc = 1.34 g cm−3, Dm = 1.33 g cm−3 for Z = 4, and R1 = 0.0772 (R2 = 0.0626) for 1474 reflections (R1 = 0.0428, R2 = 0.0422 for 903 reflections with I > 3σ(I)). The structure of 6a is similar. Key words: 3,3-dialkyl-3H-pyrazoles, 1,5-sigmatropic rearrangements of; 4,5-dialkyl-1H-pyrazoles, crystal and molecular structures; 1,5-sigmatropic rearrangements of pyrazoles, sense of.

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22

Mandour, Adel, Eslam El-Sawy, Manal Ebaid y Seham Hassan. "Synthesis and potential biological activity of some novel 3-[(N-substituted indol-3-yl)methyleneamino]-6-amino-4-aryl-pyrano(2,3-c)pyrazole-5-carbonitriles and 3,6-diamino-4-(N-substituted indol-3-yl)pyrano(2,3-c)pyrazole-5-carbonitriles". Acta Pharmaceutica 62, n.º 1 (1 de marzo de 2012): 15–30. http://dx.doi.org/10.2478/v10007-012-0007-0.

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Synthesis and potential biological activity of some novel 3-[(N-substituted indol-3-yl)methyleneamino]-6-amino-4-aryl-pyrano(2,3-c)pyrazole-5-carbonitriles and 3,6-diamino-4-(N-substituted indol-3-yl)pyrano(2,3-c)pyrazole-5-carbonitriles Starting from N-substituted indole-3-carboxaldehydes (1a-g) a series of new 3-[(N-substituted indol-3-yl)methyleneamino]-6-amino-4-aryl-pyrano(2,3-c)pyrazole-5-carbonitriles (3a-g and 4a-g) have been synthesized via the acid catalyzed condensation reaction of 1a-g with 3-amino-5-pyrazolone, followed by the reaction with arylidene malononitriles. A series of new 3,6-diamino-4-(N-substituted indol-3-yl)pyrano(2,3-c)pyrazole-5-carbonitriles (7a-g) have been prepared either via the base catalyzed condensation reaction of 1a-g with 3-amino-5-pyrazolone to give 6a-g, followed by the reaction with malononitrile or by the reaction of N-substituted-3-indolylidene malononitriles (5a-g) with 3-amino-5-pyrazolone. According to the obtained results, the newly synthesized compounds possess significant anti-inflammatory, analgesic and anticonvulsant activities. The anticonvulsant potency of certain tested compounds was more pronounced than both anti-inflammatory and analgesic activities. Moreover, most of the newly synthesized compounds possess potential antimicrobial activity against Escherichia coli and Pseudomonas aeruginosa.

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23

Usami, Yoshihide, Kodai Sumimoto, Azusa Kishima, Yuya Tatsui, Hiroki Yoneyama y Shinya Harusawa. "Synthesis of Dihydropyrano[3,2-c]pyrazoles via Double Bond Migration and Ring-Closing Metathesis". Molecules 24, n.º 2 (15 de enero de 2019): 296. http://dx.doi.org/10.3390/molecules24020296.

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Three types of pyrazole-fused heterobicycles, i.e., 1,5-, 1,7-, and 2,5-dihydropyrano[3,2-c]pyrazoles, were synthesized from 4-allyloxy-1H-pyrazoles. A sequence of the Claisen rearrangement of 4-allyloxy-1H-pyrazoles, ruthenium-hydride-catalyzed double bond migration, O-allylation, and ring-closing metathesis was employed in this study.

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24

Dodiya, Dipti, Amit Trivedi, Samir Jarsania, Shailesh Vaghasia y 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, n.º 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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25

Dotsenko, Victor V., Vladimir A. Dushenko, Nikolai A. Aksenov, Inna V. Aksenova y Evgeniy E. Netreba. "The First Synthesis of [1,2]oxaphosphinino[6,5-c]pyrazoles by Thiophosphorylation of 6-Aminopyrano[2,3-c]pyrazole-5-Carbonitriles". Proceedings 9, n.º 1 (14 de noviembre de 2018): 26. http://dx.doi.org/10.3390/ecsoc-22-05680.

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The reaction of 6-amino-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles with phosphorus sulfide in boiling pyridine leads to the formation of the unexpected [1,2]oxaphosphinino[6,5-c]pyrazoles. The structure of the products was confirmed with 2D Nuclear Magnetic Resonance (NMR) spectroscopy and X-ray analysis.

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26

Rastogi, Sameer, Tarun Virmani, Charan Deshwal y Joyti Gupta. "Novel Synthesis of Functionally Substituted Pyrazole and Biological Evaluation". Volume 1, Issue 1 : October 2015 – December 2015 1, n.º 1 (15 de noviembre de 2015): 18–22. http://dx.doi.org/10.32463/rphs.2015.v01i01.04.

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In the present work, a series of some new substituted 3, 5 dimethyl pyrazole (4a-c), 3-methyl pyrazol-5-one derivatives (5a-c), 3-Methyl- 1-(substituted phenyl) pyrazol-5-ones (7a-b) and 2, 3-dimethyl-1- (substituted phenyl) pyrazol-5-one (8a-b) has been synthesized. All the synthesized compounds were characterized by physical, chemical, analytical and spectral data. The newly synthesized compounds were screened for anti-inflammatory activity. The biological in vivo evaluation of these compounds in experimental models (carrageenan-induced oedema) proved the presence of anti-inflammatory activity.

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27

Mokhonova, Inna D., Evgenij A. Maksimov, Irina V. Ledenyona, Alevtina Y. Yegorova y Khidmet S. Shikhaliev. "Reactions of 3H-furan-2-ones and 2H-chromen-2-ones with pyrazole-3(5)-diazonium salts". Heterocyclic Communications 24, n.º 4 (28 de agosto de 2018): 183–85. http://dx.doi.org/10.1515/hc-2017-0192.

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AbstractDerivatives of the new heterocyclic system, 6H-chromeno[4,3-e]pyrazolo[5,1-c][1,2,4]triazin-6-one, were obtained by the reaction of pyrazole-3(5)-diazonium salts with 4-hydroxy-2H-chromen-2-one. Similar reactions with 5-phenyl-3H-furan-2-one followed by intramolecular heterocyclization furnished 6-(4-halophenyl)-7-alkyl-2-phenylfuro[2,3-e]pyrazolo[5,1-c][1,2,4]triazines.

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28

Kulkarni, Pravin S., Swapnil R. Sarda, Amol U. Khandebharad, Mazahar Farooqui y Brijmohan R. Agrawal. "Synthesis and Biological Screening of Novel 5-(5-Aryl-1-phenyl-1H-pyrazol-3-yl)-3-aryl-1,2,4-oxadiazole Derivatives". Asian Journal of Chemistry 34, n.º 1 (2021): 209–15. http://dx.doi.org/10.14233/ajchem.2022.23497.

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A new series of 5-(5-aryl-1-phenyl-1H-pyrazol-3-yl)-3-aryl-1,2,4-oxadiazole (6a-o) have been synthesized by a cyclocondensation reaction of ethyl 5-(4-chlorophenyl)-1-phenyl-1H-pyrazole-3- carboxylate (3a-c) with aryl imidoxime (5a-e). The newly synthesized pyrazolyl-1,2,4-oxadiazole (6a-o) derivatives were characterized by spectroscopic techniques and screened for in vitro antibacterial activity against Bacillus subtilis (NCIM 2063), Staphylococcus albus (NCIM 2178), Escherichia coli (NCIM 2574), Proteus mirabilis (NCIM 2388) and in vitro antifungal activity against Aspergillus niger (ATCC 504) Candida albicans (NCIM 3100).

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29

Bustos, Carlos, Luis Alvarez-Thon, Tania Oportus, Angela Mesías-Salazar y Ricardo Baggio. "On substituted pyrazole derivatives. II. (E)-1-(4-{[1-(4-Fluorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl]diazenyl}phenyl)ethanone and (E)-1-(4-chlorophenyl)-3,5-dimethyl-4-[2-(2-nitrophenyl)diazenyl]-1H-pyrazole". Acta Crystallographica Section C Structural Chemistry 71, n.º 1 (1 de enero de 2015): 53–58. http://dx.doi.org/10.1107/s2053229614024619.

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The molecular structures of (E)-1-(4-{[1-(4-fluorophenyl)-3,5-dimethyl-1H-pyrazol-4-yl]diazenyl}phenyl)ethanone, C19H17FN4O, (III), and (E)-1-(4-chlorophenyl)-3,5-dimethyl-4-[2-(2-nitrophenyl)diazenyl]-1H-pyrazole, C17H14ClN5O2, (IV), prepared by reaction of the corresponding β-diketohydrazones with substituted arylhydrazines in acid media, are nonplanar, with the planes of the lateral phenyl rings forming dihedral angles with that of the central pyrazole ring varying from 2.71 (7) to 45.22 (7)°. The crystal structures are supported by C—H...O, C—H...π and π–π weak intermolecular interactions together with some unusual trifurcated C—Cl...Cl—C contacts, which are discussed in detail.

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30

Frey, Guido D., Wolfgang W. Schoeller y Eberhardt Herdtweck. "Solid-state and Calculated Electronic Structure of 4-Acetylpyrazole". Zeitschrift für Naturforschung B 69, n.º 7 (1 de julio de 2014): 839–43. http://dx.doi.org/10.5560/znb.2014-4064.

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The crystal structure of 1-(1H-pyrazol-4-yl)ethanone (commonly known as 4-acetylpyrazole; C5H6N2O) was determined from single-crystal X-ray data at 173 K: monoclinic, space group P21/n (no. 14), a = 3.865(1), b = 5.155(1), c = 26.105(8) Å, β = 91.13(1)°, V = 520.0(2) Å3 and Z = 4. The adjacent molecules assemble into a wave-like ribbon structure in the solid state, linked by strong intermolecular N-H...N hydrogen bonds between the pyrazole rings and a weak C-H...O=C hydrogen bond involving the carbonyl group. The ribbons are stacked in the solid state via weak π interactions between the pyrazole rings.

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31

Herfindo, Noval, Riska Prasetiawati, Daniel Sialagan, Neni Frimayanti y Adel Zamri. "Synthesis, Antiproliferative Activity and Molecular Docking Studies of 1,3,5-Triaryl Pyrazole Compound as Estrogen α Receptor Inhibitor Targeting MCF-7 Cells Line". Molekul 15, n.º 1 (23 de marzo de 2020): 18. http://dx.doi.org/10.20884/1.jm.2020.15.1.585.

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This research has been successfully synthesized three compounds of 1,3,5-triaryl pyrazole derivatives by two steps reaction. Firstly, pyrazoline (4a-c) compound was obtained by one-pot reaction of aromatic ketones, aldehyde and hydrazine in basic condition. Then, pyrazole (5a-c) compound was obtained by oxidative aromatization of compound 4 in the presense of acetic acid. Chemical structure of predicted molecules was confirmed by FTIR, NMR and HRMS spectroscopy data analysis. Antiproliferative activity of compound 5a-c were evaluated by in vitro assay against MCF-7 cells line and molecular docking simulation against ERα (PDB ID: 3ERT) using MOE 2019. Biological evaluation result showed that pyrazole compounds had weak antiproliferative activity against MCF-7 cells with IC50 were > 1000 µM, whereas the docking studies agrees the result.

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32

Hafez, Hend N. y Abdel-Rhman B. A. El-Gazzar. "Synthesis of pyranopyrazolo N-glycoside and pyrazolopyranopyrimidine C-glycoside derivatives as promising antitumor and antimicrobial agents". Acta Pharmaceutica 65, n.º 3 (1 de septiembre de 2015): 215–33. http://dx.doi.org/10.1515/acph-2015-0022.

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Abstract As a part of systematic investigation of the synthesis and biological activities of pyrazole analogues linked to various heterocyclic systems, a new series of pyrazolo-N-glycoside derivatives, pyrazolopyranopyrimidine and C-glycoside of pyrazolopyranotriazolo-pyrimidine derivatives was synthesized through the reaction of the key intermediate 6-amino-3-methyl-4-(substituted-phenyl)-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (3a,b) with different reagents. Structures of the newly synthesized compounds were elucidated by elemental microanalysis and spectroscopic methods. The compounds were subjected to in vitro antitumor evaluation using the MTT assay. N-(β-D-ribofuranosyl)- and N-(β-D-xylofuranosyl)-6{[(1E)-4-chlorophenyl)-methylene] amino}4-(4-florophenyl)-3-methyl-1,4-dihydropyrano[2,3-c]-pyrazole-5-carbonitrile (6a,b) were the most active compounds against three human cancer cell lines. Also, most of the newly synthesized compounds exhibited high activity towards Gram-negative and Gram-positive bacteria. Compound 6a exhibited excellent activity towards bacteria compared to ofloxacine as the reference drug.

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Manojkumar, Parameswaran, Thengungal Ravi y Gopalakrishnan Subbuchettiar. "Synthesis of coumarin heterocyclic derivatives with antioxidant activity and in vitro cytotoxic activity against tumour cells". Acta Pharmaceutica 59, n.º 2 (1 de junio de 2009): 159–70. http://dx.doi.org/10.2478/v10007-009-0018-7.

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Synthesis of coumarin heterocyclic derivatives with antioxidant activity andin vitrocytotoxic activity against tumour cellsThe aim of the present work was to synthesise coumarinyl heterocycles and to elucidate the potential role of these compounds as antioxidants and cytotoxic agents against Dalton's lymphoma ascites tumour cells (DLA) and Ehrlich ascites carcinoma cells (EAC). The synthesis of coumarin derivatives containing pyrazole, pyrazolone, thiazolidin-4-one, 5-carboxymethyl-4-thiazolidinone and 3-acetyl-1,3,4-oxadiazole ring is reported. 4-Methylcoumarinyl-7-oxyacetic acid hydrazide (1) reacted with arylazopropanes or hydrazono-3-oxobutyrate derivatives to form pyrazole (3a-c) and pyrazolone derivatives (5a-c). Heterocyclisation of Schiff's bases of 1 with thioglycolic acid, thiomalic acid or acetic anhydride afforded novel heterocyclic derivatives 4-thiazolidinones (7a-c), 5-carboxymethyl-4-thiazolidinones (8a-c) and oxadiazoles (9a-c), respectively. Some of the compounds showed promising antioxidant activityin vitroand cytotoxic activity against DLA cells and EAC cells.

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34

Taguchi, Alexander, Oleksandr Kokhan y Colin Wraight. "Pyrazole Cytochrome C Complexes". Biophysical Journal 102, n.º 3 (enero de 2012): 466a—467a. http://dx.doi.org/10.1016/j.bpj.2011.11.2559.

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35

Ding, Zhengwei, Qitao Tan, Mingchun Gao y Bin Xu. "Copper-catalyzed aerobic cascade cycloamination and acyloxylation: a direct approach to 4-acyloxy-1H-pyrazoles". Organic & Biomolecular Chemistry 13, n.º 16 (2015): 4642–46. http://dx.doi.org/10.1039/c5ob00409h.

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An efficient copper-catalyzed regioselective olefinic C(sp²)–H bond cycloamination and acyloxylation was developed to give acyloxylated pyrazoles under mild conditions, which combines the formation of the pyrazole skeleton and installation of an acyloxyl group in a single step.

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36

Abunada, Nada M., Hamdi M. Hassaneen, Ahmed S. M. Abu Samaha y Omar A. Miqdad. "Synthesis and antimicrobial evaluation of some new pyrazole, pyrazoline and chromeno[3,4-c]pyrazole derivatives". Journal of the Brazilian Chemical Society 20, n.º 5 (2009): 975–87. http://dx.doi.org/10.1590/s0103-50532009000500024.

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37

Dalal, Kiran S., Yogesh A. Tayade, Yogesh B. Wagh, Darshak R. Trivedi, Dipak S. Dalal y Bhushan L. Chaudhari. "Bovine serum albumin catalyzed one-pot, three-component synthesis of dihydropyrano[2,3-c]pyrazole derivatives in aqueous ethanol". RSC Advances 6, n.º 18 (2016): 14868–79. http://dx.doi.org/10.1039/c5ra13014j.

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A BSA catalyzed synthesis of dihydropyrano[2,3-c]pyrazole derivatives via a one pot, three component reaction of an aldehyde/ketone/isatin, malononitrile and 3-methyl-1H-pyrazol-5-(4H)-one in H₂O–EtOH (7 : 3) at ambient temperature is reported.

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38

Biswas, Swapan Kumar y Debasis Das. "One-pot Synthesis of Pyrano[2,3-c]pyrazole Derivatives via Multicomponent Reactions (MCRs) and their Applications in Medicinal Chemistry". Mini-Reviews in Organic Chemistry 19, n.º 5 (agosto de 2022): 552–68. http://dx.doi.org/10.2174/1570193x19666211220141622.

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Background: Many pyrano[2,3-c]pyrazole derivatives display diverse biological activities and some of them are known as anticancer, analgesic, anticonvulsant, antimicrobial, antiinflammatory, and anti-malarial agents. In recent years, easy convergent, multicomponent reactions (MCRs) have been adopted to make highly functionalizedpyrano[2,3-c]pyrazole derivatives of biological interest. The synthesis of 1,4-dihydropyrano[2,3-c]pyrazole (1,4-DHPP, 2), 2,4- dihydropyrano[2,3-c]pyrazole (2,4-DHPP, 3), 4-hydroxypyrano[2,3-c]pyrazole (4-HPP, 4) derivatives, 1,4,4-substitied pyranopyrazole (SPP, 5) were reported via two-, three-, four- and fivecomponent reactions (MCRs). Methods: This review article compiles the preparation of pyrano[2,3-c]pyrazole derivatives, and it highlights the applications of various pyrano[2,3-c]pyrazole derivatives in medicinal chemistry. Results: Varieties of pyrano[2,3-c]pyrazole derivatives were achieved via “One-pot” multicomponent reactions (MCRs). Different reaction conditions in the presence of a catalyst or without catalysts were adapted to prepare the pyrano[2,3-c]pyrazole derivatives. Conclusion: Biologically active pyrano[2,3-c]pyrazole derivatives were prepared and used in drug discovery research.

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Prhavc, Marija y Jože Kobe. "SYNTHESIS OF PYRAZOLO[4,3-C]PYRIDINE C-RIBONUCLEOSIDESVIAAN EFFECTIVE TETRAZOLE TO PYRAZOLE TRANSFORMATION". Nucleosides and Nucleotides 15, n.º 11-12 (noviembre de 1996): 1779–95. http://dx.doi.org/10.1080/07328319608002732.

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40

Sikandar, Sana, Ameer Fawad Zahoor, Sajjad Ahmad, Muhammad Naveed Anjum, Mirza Nadeem Ahmad y Muhammad Sami Ullah Shah. "L-Cysteine Catalyzed Environmentally Benign One-pot Multicomponent Approach Towards the Synthesis of Dihydropyrano[2,3-c]pyrazole Derivatives". Current Organic Synthesis 17, n.º 6 (25 de septiembre de 2020): 457–63. http://dx.doi.org/10.2174/1570179417666200511092332.

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Background: The pyrano[2,3-c]pyrazole derivatives are important building blocks of many biologically active compounds owing to their diverse biological potential for example, anti-inflammatory, anticancer, anti-microbial and anti-oxidant properties. Objective: Keeping in mind the wide range of applications of pyrano[2,3-c]pyrazoles, herein we intended to develop a novel synthetic methodology for dihydropyranopyrazoles. We were also interested in determining the influence of amino acids and dipeptides as a catalyst on the synthesis of pyrano[2,3-c]pyrazole derivatives. Methods: To achieve our objectives, we used a one-pot multi-component reaction of ethyl 3-oxobutanoate, propanedinitrile, hydrazine monohydrate and several substituted benzaldehydes by using different catalysts and solvents to synthesize our desired products in the presence of various catalysts. Results and Discussion: We found that optimal conditions for the preparation of pyrano[2,3-c]pyrazoles were L-cysteine (0.5 mol) in the presence of water:ethanol (9:1) at 90 °C. Various 1,4-dihydropyrano[2,3- c]pyrazoles were afforded by using several substituted benzaldehydes in 66-97% yields. Conclusion: We described a green and environmentally benign method to synthesize pyrano[2,3-c]pyrazoles in a one-pot four component reaction of ethyl 3-oxobutanoate, propanedinitrile, hydrazine monohydrate and different substituted benzaldehyde in the presence of L-cysteine in aqueous ethanol (9:1) at 90 oC. Excellent yields of the products, simple work-up, easily available starting materials, use of green solvents, naturally occurring catalyst, non-toxicity, non-chromatographic purification and environmentally benign reaction conditions are some main advantages of this protocol.

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Hrynyshyn, Yevhenii, Hanna Musiichuk, Olena Komarovska-Porokhnyavets, Oksana Is’kiv, Nataliia Moskalenko, Maryna Stasevych, Nazar Tsyzoryk y Mykhailo Vovk. "Synthesis and Antimicrobial Activity of 4-Arylthio- and 4 Alkylthiofunctionalized Pyrazolo[1,5-a]pyrazines". Ukrainian Chemistry Journal 85, n.º 1 (15 de febrero de 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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42

Kantlehner, Willi, Jochen Mezger, Rüdiger Stieglitz, Kai Edelmann, Hansjörg Lehmann, Markus Vettel, Ralf Kreß, Wolfgang Frey y Sebastian Ladendorf. "Orthoamide, LXV [1]. Kondensationsreaktionen von Amidinen, Guanidinen, Hydrazin und Hydrazin-Derivaten mit Orthoamiden von Alkincarbonsäuren / Orthoamides,LXV [1]. Condensation Reactions of Amidines, Guanidines, Hydrazine and Hydrazine Derivatives with Orthoamides of Alkyne Carboxylic Acids". Zeitschrift für Naturforschung B 62, n.º 8 (1 de agosto de 2007): 1015–29. http://dx.doi.org/10.1515/znb-2007-0804.

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The orthoamide derivatives 4 react with amidines 10 and guanidines 11 to give 4-dimethylaminopyrimidines 12. The 3-dimethylamino-pyrazoles 13a - c can be prepared from orthoamides 4 and hydrazine. The hydrazine derivative 14, whose constitution was established by crystal structure analysis, is obtained in low yield when hydrazine is added dropwise to a boiling solution of 4d in THF.Methyl- and phenylhydrazine, undergo reaction with the orthoamides 4a, c yielding mixtures of the isomeric pyrazoles 19 and 20. The reaction of 4c with acylhydrazines 21a - e affords the pyrazole 13b. The pyrazole 26 is produced in the reaction of 4a and acet-hydrazide according to this scheme, whereas 4a reacts with aromatic acid hydrazides 21c - e to give condensation products, which are presumably amidrazones 28. The 4,5-diaza-octatetraene derivative 30 results from the reaction of 4c with p-toluenesulfonylhydrazide. Ketene aminals 34a - c are the products of the reaction of the orthoamides 4b - d with 4,4-dimethylthiosemicarbazide 34, which cyclize on heating to give highmelting pyrazolethiones 35a - c. According to the crystal structure analysis of 35c the compounds have zwitterionic character and are associated via hydrogen bridges in the solid state.

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43

Zhang, Shijie, Zhenguo Gao, Di Lan, Qian Jia, Ning Liu, Jiaoqiang Zhang y Kaichang Kou. "Recent Advances in Synthesis and Properties of Nitrated-Pyrazoles Based Energetic Compounds". Molecules 25, n.º 15 (30 de julio de 2020): 3475. http://dx.doi.org/10.3390/molecules25153475.

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Nitrated-pyrazole-based energetic compounds have attracted wide publicity in the field of energetic materials (EMs) due to their high heat of formation, high density, tailored thermal stability, and detonation performance. Many nitrated-pyrazole-based energetic compounds have been developed to meet the increasing demands of high power, low sensitivity, and eco-friendly environment, and they have good applications in explosives, propellants, and pyrotechnics. Continuous and growing efforts have been committed to promote the rapid development of nitrated-pyrazole-based EMs in the last decade, especially through large amounts of Chinese research. Some of the ultimate aims of nitrated-pyrazole-based materials are to develop potential candidates of castable explosives, explore novel insensitive high energy materials, search for low cost synthesis strategies, high efficiency, and green environmental protection, and further widen the applications of EMs. This review article aims to present the recent processes in the synthesis and physical and explosive performances of the nitrated-pyrazole-based Ems, including monopyrazoles with nitro, bispyrazoles with nitro, nitropyrazolo[4,3-c]pyrazoles, and their derivatives, and to comb the development trend of these compounds. This review intends to prompt fresh concepts for designing prominent high-performance nitropyrazole-based EMs.

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44

Wang, Yu-Feng, Chun-Hua Yu y Run-Qiang Zhu. "An iron(III) complex salt containing pyrazole as both ligand and counter-ion: bis(1H-pyrazol-2-ium) pentacyanido(1H-pyrazole-κN 2)ferrate(III)". Acta Crystallographica Section C Structural Chemistry 70, n.º 5 (9 de abril de 2014): 437–39. http://dx.doi.org/10.1107/s2053229614007128.

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The title compound, (C3H5N2)2[Fe(CN)5(C3H4N2)], is composed of a mononuclear [Fe(CN)5(pyrazole)]2− dianion and two 1H-pyrazol-2-ium cations. A three-dimensional supramolecular network is formed through a rich scheme of N—H...N hydrogen bonds and C—H...π interactions among the cations and anions.

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45

Mague, Joel T., Shaaban K. Mohamed, Mehmet Akkurt, Talaat I. El-Emary y 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, n.º 11 (31 de octubre de 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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46

Hassan, Alaa A., Nasr K. Mohamed, Ahmed M. Shawkya y Dietrich Döpp. "Pyrazole, pyrazolo[1,2-c]-1,3,4-thiadiazole and thiadiazepine derivatives from thiosemicarbazides". Arkivoc 2003, n.º 1 (10 de julio de 2003): 118–28. http://dx.doi.org/10.3998/ark.5550190.0004.114.

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47

Koraiem, Ahmed I. M. "The synthesis of pyrazolo- and isoxazolo-[3,4-c]-pyrazole hemiazadicarbocyanine dyes". Journal of Chemical Technology and Biotechnology. Chemical Technology 34, n.º 2 (29 de mayo de 2007): 43–50. http://dx.doi.org/10.1002/jctb.5040340202.

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48

Sharma, Naresh, Sanjay Parihar, R. N. Jadeja, Rajni Kant y Vivek K. Gupta. "Crystal structure of (Z)-1-(3,4-dichlorophenyl)-3-methyl-4-[(naphthalen-1-ylamino)(p-tolyl)methylidene]-1H-pyrazol-5(4H)-one". Acta Crystallographica Section E Structure Reports Online 70, n.º 9 (1 de agosto de 2014): o955—o956. http://dx.doi.org/10.1107/s1600536814017140.

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The title Schiff base compound, C28H21Cl2N3O, was synthesized by the condensation of 1-(3,4-dichlorophenyl)-3-methyl-4-(4-methylbenzoyl)-1H-pyrazol-5(4H)-one with 1-aminonaphthalene. Thep-tolyl ring is normal to the pyrazole ring, with a dihedral angle of 88.02 (14)°, and inclined to the naphthalene ring system by 78.60 (12)°. The pyrazole ring is inclined to the naphthalene ring system and the dichloro-substituted benzene ring by 63.30 (12) and 11.03 (13)°, respectively. The amino group and carbonyl oxygen atom are involved in an intramolecular N—H...O hydrogen bond enclosing anS(6) ring motif. There is also a short C—H...O contact involving the carbonyl O atom and the adjacent benzene ring. In the crystal, molecules are linked by C—H...π interactions, forming a three-dimensional structure.

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49

Su, Ping, Xue-gang Song, Ren-qiang Sun y Xing-man Xu. "Hydrogen bonding in the crystal structure of the molecular salt of pyrazole–pyrazolium picrate". Acta Crystallographica Section E Crystallographic Communications 72, n.º 6 (27 de mayo de 2016): 861–63. http://dx.doi.org/10.1107/s2056989016008215.

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The asymmetric unit of the title organic salt [systematic name: 1H-pyrazol-2-ium 2,4,6-trinitrophenolate–1H-pyrazole (1/1)], H(C3H4N2)2+·C6H2N3O7−, consists of one picrate anion and one hydrogen-bonded dimer of a pyrazolium monocation. The H atom involved in the dimer N—H...N hydrogen bond is disordered over both symmetry-unique pyrazole molecules with occupancies of 0.52 (5) and 0.48 (5). In the crystal, the component ions are linked into chains along [100] by two different bifurcated N—H...(O,O) hydrogen bonds. In addition, weak C—H...O hydrogen bonds link inversion-related chains, forming columns along [100].

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50

Palka, Barbara, Angela Di Capua, Maurizio Anzini, Gyté Vilkauskaité, Algirdas Šačkus y Wolfgang Holzer. "Synthesis of trifluoromethyl-substituted pyrazolo[4,3-c]pyridines – sequential versus multicomponent reaction approach". Beilstein Journal of Organic Chemistry 10 (31 de julio de 2014): 1759–64. http://dx.doi.org/10.3762/bjoc.10.183.

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A straightforward synthesis of 6-substituted 1-phenyl-3-trifluoromethyl-1H-pyrazolo[4,3-c]pyridines and the corresponding 5-oxides is presented. Hence, microwave-assisted treatment of 5-chloro-1-phenyl-3-trifluoromethylpyrazole-4-carbaldehyde with various terminal alkynes in the presence of tert-butylamine under Sonogashira-type cross-coupling conditions affords the former title compounds in a one-pot multicomponent procedure. Oximes derived from (intermediate) 5-alkynyl-1-phenyl-3-trifluoromethyl-1H-pyrazole-4-carbaldehydes were transformed into the corresponding 1H-pyrazolo[4,3-c]pyridine 5-oxides by silver triflate-catalyzed cyclization. Detailed NMR spectroscopic investigations (1H, 13C, 15N and 19F) were undertaken with all obtained products.

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