Bibliografías temáticas / C]pyrazole

Literatura académica sobre el tema "C]pyrazole"

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Publicado: 1 de julio de 2022

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Artículos de revistas sobre el tema "C]pyrazole":

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.

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.

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.

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.

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.

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.

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.

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.

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.

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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Tesis sobre el tema "C]pyrazole":

Ostache, Nicu-Carmin. "Synthèse et fonctionnalisation de bicycles 5-5 polyazotés : pyrazolo[3,4-d]thiazoles et pyrazolo[3,4-c]pyrazoles". Thesis, Orléans, 2019. http://intranet.univ-orleans.fr/bibliotheques/theses/nicu-cosmin-ostache_3378_vm.pdf/.

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Les structures bicycliques azotées sont parmi les entités les plus utilisées dans le domaine thérapeutique.Les bicycles 5:5 polyazotés sont des structures moins décrites que leurs analogues 6:6 ou6:5. Malgré le potentiel pharmacologique des pyrazolo [3,4-d] thiazoles et des pyrazolo [3,4-c] pyrazoles,deux exemples de ces familles rares, seuls quelques procédés de préparation et de fonctionnalisationdirecte de ces charpentes hétérocycliques sont décrits.De ce fait, l’objectif principal de nos recherches vise à développer de nouvelles voies de synthèse vers cesdeux charpentes bicycliques et ce, à partir de substrats facilement accessibles. Des stratégies efficaces ontété mises au point et s’appuient sur réactions de condensations avec des hydrazines, des N-cyclisationsintramoléculaires, des halogénations chimiosélectives et diverses réactions de couplage-croisé. De surcroît,le motif pyrazolo[3,4-d]thiazole a été fusionné à une structure triazapentalène, afin d’évaluer les propriétésspectroscopiques
Nitrogen-rich fused bicyclic structures are undisputedly one of the most used scaffolds for therapeutic use.The 5:5 polynitrogenated bicycles are moieties considerably less documented then their 6:6 or 6:5analogues. Despite the pharmacological potential of the pyrazolo[3,4-d]thiazoles and of thepyrazolo[3,4-c]pyrazoles, two examples of such rare families, only few methods of preparation and directfunctionalization of these heterocyclic moieties have been described.In this context, the main goal of our research aims at exploring new routes towards these bicyclic systemsfrom readily available and affordable starting materials. Efficient strategies were developed relying onhydrazine condensations, on intramolecular N-cyclizations, on chemo-selective halogenation and variouscross-coupling reactions. Moreover, the pyrazolo[3,4-d]thiazole entity was fused to a triazapentalenestructure in order to assess the spectroscopic properties

Kerr, G. "The synthesis of pyrazole C-nucleosides as potential antitumour agents". Thesis, Heriot-Watt University, 1992. http://hdl.handle.net/10399/1454.

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Smith, Duncan. "The synthesis of pyrazole C-nucleosides containing D-arabinose and D-xylose". Thesis, Heriot-Watt University, 1985. http://hdl.handle.net/10399/1617.

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Böhnisch, Torben. "C₂-Symmetric Pyrazole-Bridged Ligands and Their Application in Asymmetric Transition-Metal Catalysis". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://hdl.handle.net/11858/00-1735-0000-0028-876A-6.

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Ejjoummany, Abdelaziz. "Design et fonctionnalisation d’hétérocycles originaux de type bicycliques [5-5] et tricycliques [6-5-6] à visée thérapeutique potentielle". Thesis, Orléans, 2020. http://www.theses.fr/2020ORLE3141.

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L’accès à de nouveaux composés hétérocycliques originaux biologiquement actifs, constitue l’un des principaux objectifs de notre groupe de recherche. Dans ce contexte, les travaux de cette thèse ont pour but principal, la conception de trois nouvelles familles de composés hétérocycliques contenant un motif pyrazolique susceptibles de présenter des activités biologiques, à savoir les pyrido[1',2':1,5]pyrazolo[4,3-d]pyrimidine, les pyrrolo[3,4-c]pyrazoles et les pyrazolo[5,1-b]thiazoles. Ce manuscrit est essentiellement dédié à un travail de méthodologie décrivant les différentes voies d’accès à ces hétérocycles originaux, tricycliques et bicycliques potentiellement modulables. La réactivité de ces synthons clés est ensuite étudiée avec divers procédés de fonctionnalisation palladocatalysés (Activation au PyBrOP-(hétéro)arylation, Liebeskind-Srogl, Suzuki-Miyaura, Buchwald-Hartwig, C-H arylation, substitution nucléophile aromatique) pour élaborer d’intéressantes chimiothèques construites autour de ces structures inédites, ouvrant ainsi de nombreuses perspectives pharmacologiques
The access to new original biologically active heterocyclic compounds, is one of the main objectives of our research group. In this context, the main purpose of this thesis is the design of three new families of heterocyclic compounds containing a pyrazolic motif that may exhibit biological activities, namely pyrido[1',2': 1.5]pyrazolo[4,3-d]pyrimidine, pyrrolo[3,4-c]pyrazole and pyrazolo[5,1-b]thiazole.This manuscript is essentially dedicated to a methodology work describing the different routes of access to these originals and potentially modular tricyclic and bicyclic precursors. The reactivity of these key synthons is then studied towards aromatic nucleophilic substitutions reactions and various pallado-catalyzed methods of functionalization (Activation with PyBrOP- (hetero) arylation, Liebeskind-Srogl, Suzuki-Miyaura, Buchwald-Hartwig, C-H arylation, aromatic nucleophilic substitution) to develop interesting libraries built around these unusual structures, thus opening numerous pharmacological perspectives

Ervithayasuporn, Vuthichai. "Synthesis and photochemistry of pyrano[2,3-c]pyrazoles". Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-042006-160619/.

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ERVITHAYASUPORN, VUTHICHAI. "Synthesis and Photochemistry of Pyrano[2,3-c]pyrazoles". Digital WPI, 2006. https://digitalcommons.wpi.edu/etd-theses/228.

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Two different synthetic approaches to the synthesis of pyrano[2,3-c]pyrazoles have been investigated. In one approach, dehydroacetic acid derivatives were treated with phenylhydrazine and methylhydrazine led to the formation of the phenylhydrazones and methylhydrazones, which undergo rearrangement in refluxing acetic acid to diketo-phenylpyrazoles and diketo-methylpyrazoles. Upon treatment with a mixture of acetic and sulfuric acid these compounds isomerize to the phenylpyrano[2,3-c]pyrazol-4-one and methylpyrano[2,3-c]pyrazol-4-one derivatives. In a second approach, phenylhydrazine and methylhydrazine reacted with dimethyl(methoxymethylene)malonate (34) to give phenylpyrazole and methylpyrazole ester derivatives which were converted to phenylpyrazolone and methylpyrazolone by hydrolysis and decarboxylation. C-acylation of these compounds with trans-cinnamoyl chloride gave ÃƒÂ¡,ÃƒÂ¢-unsaturated-4-acetyl-5-hydroxypyrazoles. Bromination of these ÃƒÂ¡,ÃƒÂ¢-unsaturated-4-acetyl-5-hydroxypyrazoles with spontaneous cyclization, followed by dehydrobromination led to pyrano[2,3-c]pyrazol-4-one derivatives, respectively. Phototochemical excitation of 1-phenyl and 1-methylpyrano[2,3-c]pyrazol-4-ones in acetonitrile led to the formation of cis-head-to-tail [2+2] cycloaddition products. Irradiation in ethanol solvent led to photodimerization and to photofragmentation to yield pyrazole ethylesters.

Adcock, Romain. "Synthesis and reactivity of [RhI(CO)2(L)] and [RL][RhI2(CO)2] rhodium complexes where L is a nitrogen-containing ligand for the methanol carbonylation reaction". Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0123.

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Ce travail est centré sur la synthèse de complexes du rhodium contenant un ligand azoté et leur mise en œuvre dans la réaction catalytique de carbonylation du méthanol en acide acétique. Dans une première partie, nous nous intéressons à la préparation de complexes neutres de formule générale [RhI2(CO)(L)] (L = amines, imidazoles et pyrazoles) et à quelques homologues chlorés. Ces complexes plans carrés manifestent une réactivité directement liée à l’encombrement stérique du ligand azoté L dans la réaction d’addition oxydante de l’iodomethane suivie de la cis-migration du groupement méthyle pour former l’espèce acétyle. Dans une deuxième partie, les complexes précédents ont été engagés dans des essais catalytiques de carbonylation du méthanol dans les conditions du procédé industriel. Comme il s’est avéré que les complexes neutres se transforment en espèce [RhI2(CO)2]- pour laquelle les contre-cations associés sont constitués du ligand azoté protoné ou methylé, nous avons effectué la préparation et la caractérisation des complexes [HNR3][RhI2(CO)2] ou [MeNR3][RhI2(CO)2]. Par IR, RMN et électrochimie, nous nous sommes intéressés aux phénomènes d’appariement d’ions et nous montrons qu’il s’agit dans le meilleur des cas d’interactions hydrogènes. Celles-ci influent la vitesse de la réaction oxydante de CH3I. Dans la dernière partie, nous avons complété une étude, précédemment initiée au laboratoire, sur le mécanisme, qui dans la dernière étape du cycle catalytique permet de passer de l’espèce acétyle [RhI3(COCH3)(CO)2]- à l’espèce active [RhI2(CO)2]- avec production de l’iodure d’acyle. A l’inverse du concept admis d’élimination réductrice de CH3COI suivie de son hydrolyse immédiate en CH3COOH et HI, nous montrons, avec l’appui de calculs théoriques (DFT) qu’en fait un ligand I- est substitué par un ligand acetate pour conduire à l’espèce [RhI2(OAc)(COCH3)(CO)2]-. L’élimination réductrice produit alors l’anhydride acétique qui est hydrolysé en CH3COOH régénérant [RhI2(CO)2]-. Un tel mécanisme opère en présence d’ions acetate dans les milieux faiblement hydratés visés par l’industriel
This study focuses on the synthesis and reactivity of rhodium complexes bearing N- containing ligands or counter-cations for the [Rh]-catalyzed methanol carbonylation reaction to produce acetic acid under the industrial Celanese Acid Optimization (AO) process conditions. In a first part, full synthesis and characterization of neutral Rh(I) square planar cis- [RhX(CO)2(L)] (X = Cl or I) complexes have been described, for which L is an N-ligand belonging to the amine, imidazole or pyrazole family. For the [RhI(CO)2(L)] complexes, variable-temperature 13C{1H} NMR spectroscopy has put in evidence a fluxional behavior for the different sized L ligands involved. The rate of this fluxional process reveals to be related to both electronic and steric contributions brought by L to the Rh center. These parameters (mainly steric), supported by single-crystal X-ray analyses in the solid state, also influence significantly the kinetics of the methyl iodide oxidative addition reaction followed by rapid CO migratory insertion, the overall being the rate determining step of the [Rh]-catalyzed methanol carbonylation cycle. In absence of CO, this reaction gives rise to the corresponding neutral Rh(III) acetyl complex, which immediately dimerizes to afford [Rh(μ- I)I(COMe)(CO)(L)]2 complex, for which several X-ray crystal structures have been obtained and studied. In addition, the surprising C-H activation in the case of a tBu-pyrazole ligand giving rise to a cyclometalated Rh dimer is reported. In a second part, the reactivity of the latter neutral Rh(I) [RhI(CO)2(L)] complexes as potential precursors has been investigated by batch experiments for the methanol carbonylation reaction. Mechanistic understanding via VT-HP-NMR experiments enabled to detect mainly anionic Rh(I) [RL][RhI2(CO)2] (R = H or CH3 according to the working conditions) complexes formed by decoordination followed by quaternization of the L ligand. Despite this result, the pyrazole family ligands showed better stability under the harsh process conditions. Thus, it cannot be ruled out that equilibrium between neutral and anionic species co-exist in the reaction medium at high temperatures and that [RL]I salt dissociation occurs, restoring the L ligand into the Rh coordination sphere. At this stage we focused on the anionic Rh(I) complex and prepared a series of [XNR3][RhI2(CO)2] (X = H or CH3) species, which have been fully characterized. Infrared, NMR, conductivity experiments and DFT model calculations together put in evidence ion interactions according to the nature of the ammonium counter-cation. Protonated cations significantly impact on the kinetics of the methyl iodide oxidative addition presumably due to H-interactions with the Rh square plane. The final part deals with the mechanism of the reductive elimination reaction, the last step of the [Rh]-catalyzed methanol carbonylation cycle, which from complex [RhI3(COCH3)(CO)2]-, regenerates [RhI2(CO)2]-. In contrast to the classically admitted mechanism of reductive elimination of CH3COI followed by subsequent hydrolysis to form AcOH and HI, we demonstrate from experimental DFT calculation that substitution of an iodo ligand by an acetate ion occurs to give rise to the [RhI2(OAc)(COCH3)(CO)2]- species. Thus, reductive elimination regenerates [RhI2(CO)2]- and produces acetic anhydride, which after hydrolysis affords two molecules of acetic acid. Such a mechanism operates under process conditions at low water content with a significant amount of acetate ions

Chioua, Rachid. "Synthèse, structure et réactivité de dérivés de la 1H-pyrazolo[3,4-c]pyridine. Analogues acycliques de nucléosides". Montpellier 1, 1992. http://www.theses.fr/1992MON13526.

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Kothe, Thomas. "Reductive Binding of C‒O and Nitro Substrates at a Pyrazolate-Bridged Preorganized Dinickel Scaffold". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-1524-B.

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Capítulos de libros sobre el tema "C]pyrazole":

Angulwar, Jaman A. "Multicomponent Synthesis of 2-Substituted Derivatives of 6-Amino-5-Cyano-1,4-Dihydro-3-Methyl-1,4-Diphenylpyrano-[2,3-C]-Pyrazole Using Knoevenagel and Michael Addition". En Modern Green Chemistry and Heterocyclic Compounds, 113–36. Series statement: Innovations in physical chemistry: monographic series: Apple Academic Press, 2020. http://dx.doi.org/10.1201/9780367276942-4.

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Chandra, H., H. Fischer, F. A. Neugebauer y M. C. R. Symons. "Radical Ions of Benzo[c]cinnolines and 2,3-Dihydro-1H-benzo[c]pyrazolo[1,2-a]cinnolines". En Organic Free Radicals, 143. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73963-7_71.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of copper(II) complex of 5, 2-diphenyl-6H-pyrazolo-[1, 5-c] pyrimidine-7-thiones". En Magnetic Properties of Paramagnetic Compounds, 397–98. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49202-4_186.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of copper(II) complex of 5-(p-tolyl)-2-phenyl-6H-pyrazolo- [1, 5-c]pyrimidine-7-thione". En Magnetic Properties of Paramagnetic Compounds, 393–94. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49202-4_184.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of copper(II) complex of 5-(p-methoxyphenyl)-2-phenyl-6H-pyrazolo- [1, 5-c]pyrimidine-7-thiones". En Magnetic Properties of Paramagnetic Compounds, 395–96. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49202-4_185.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of copper(II) complex of 5-p-chlorophenyl-2-phenyl-6H-pyrazolo- [1, 5-c]pyrimidine-7-thiones". En Magnetic Properties of Paramagnetic Compounds, 399–400. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49202-4_187.

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Pardasani, R. T. y P. Pardasani. "Magnetic properties of copper(II) complex of 5-p-bromophenyl-2-phenyl-6H-pyrazolo- [1, 5-c]pyrimidine-7-thiones". En Magnetic Properties of Paramagnetic Compounds, 401–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49202-4_188.

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Sapeta, K. y M. A. Kerr. "Fragment C–C–Pyrazole–C–C". En Science of Synthesis Knowledge Updates KU 2011/1, 1. Georg Thieme Verlag KG, 2011. http://dx.doi.org/10.1055/sos-sd-112-00063.

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Stadlbauer, W. "Fragment C—C—Pyrazole—C—C". En Five-Membered Hetarenes with Two Nitrogen or Phosphorus Atoms, 1. Georg Thieme Verlag KG, 2002. http://dx.doi.org/10.1055/sos-sd-012-00331.

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Sapeta, K. y M. A. Kerr. "Fragments Pyrazole–C–C and C–C". En Science of Synthesis Knowledge Updates KU 2011/1, 1. Georg Thieme Verlag KG, 2011. http://dx.doi.org/10.1055/sos-sd-112-00055.

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Actas de conferencias sobre el tema "C]pyrazole":

Medvedev, Michail, Michail Elinson y Alexey Ilovaisky. "Green approach to the design of functionalized medicinally privileged 4-aryl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile scaffold !" En The 15th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2011. http://dx.doi.org/10.3390/ecsoc-15-00580.

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Nikalje, Anna Pratima, Julio Seijas Vázquez, M. Pilar Vazquez-Tato y Urja Nimbalkar. "Ionic liquid [Et₃NH][HSO₄]catalyslyzed multicomponent synthesis of 6 amino-4-(Substituted phenyl)-3-methyl-2,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile ". En The 20th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2016. http://dx.doi.org/10.3390/ecsoc-20-f011.

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Ledeneva, Irina, Vitaly Didenko, Victor Dotsenko y Khidmet Shikhaliev. "Synthesis and reactions of pyrazolo[5,1-c][1,2,4]triazine-3-carbothioamides". En The 17th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2013. http://dx.doi.org/10.3390/ecsoc-17-a040.

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Stadlbaur, Wolfgang, Gerhard Hojas y Werner Fiala. "Thermal Cyclization of 2-Hydrazonoacyl-3-oxo-heterocycles to Pyrazolo[4,3-c]fused Heterocycles". En The 2nd International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 1998. http://dx.doi.org/10.3390/ecsoc-2-01669.

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Shukla, Bindesh Kumar y Umesh Yadava. "QSAR study of some pyrazolo[3,4-d]pyrimidine derivatives as the c-Src inhibitors". En INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC 2015): Proceeding of International Conference on Condensed Matter and Applied Physics. Author(s), 2016. http://dx.doi.org/10.1063/1.4946371.

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Gharib, Ali, Mina Roshani y Manouchehr Jahangir. "Efficient Catalytic Synthesis of Pyrazolo[3,4-d]pyrimidine, Pyrazolo[4,3- e][1,2,4]triazolo[1,5-c]pyrimidine, Pyrazolo[4,3-e][1,2,4]triazolo[1,5- c]pyrimidine, Pyrazolo[3,4-d]pyrimidin-4-one derivatives using Heterogeneous Preyssler Heteropolyacid, H₁₄[NaP₅W₃₀O₁₁0]/SiO₂". En The 13th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2009. http://dx.doi.org/10.3390/ecsoc-13-00169.

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Khatri, Taslimahemad Talab, Aadil Khursheed y Pushpendra Kumar. "Water mediated synthesis of pyrano[2, 3-c]pyrazoles using L-histidine as an effective catalyst". En RECENT ADVANCES IN FUNDAMENTAL AND APPLIED SCIENCES: RAFAS2016. Author(s), 2017. http://dx.doi.org/10.1063/1.4990359.

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Bireddy, Srinivasa Reddy, Venkata Ramana Reddy Chittireddy y Laxminarayana Eppakayala. "PEG-600: Greensolvent for synthesis of pyrazolo[5,1-c]thieno[3,4-e][1,2,4]triazin-6-amine". En NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM2020. AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0060858.

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Marra, Roberta K. F., Alice M. R. Bernardino, Marcos C. de Souza, Gilberto A. Romeiro, María J. Iglesias y Fernando López-Ortiz. "Synthesis of new hemilabile ligands based on phosphinic amide and pyrazolo[1,5-c]quanazoline moieties Applications in coordination chemistry". En 15th Brazilian Meeting on Organic Synthesis. São Paulo: Editora Edgard Blücher, 2013. http://dx.doi.org/10.5151/chempro-15bmos-bmos2013_201381913053.

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Razmienė, Beatričė, Eva Řezníčková, Vaida Dambrauskienė, Eglė Arbačiauskienė, Martin Kubala, Asta Žukauskaitė, Vladimir Kryštof y Algirdas Šačkus. "New 2<em>H</em>-pyrazolo[4,3-<em>c</em>]pyridines: Synthesis, optical properties and elucidation of anti-cancer activity". En 6th International Electronic Conference on Medicinal Chemistry. Basel, Switzerland: MDPI, 2020. http://dx.doi.org/10.3390/ecmc2020-07448.

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