- Preparation method of pyrazole derivative (by machine translation)
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The preparation method comprises the following steps: mixing an alkyne propyl alcohol derivative, a halogen source, an acid and a solvent, heating and reacting, and reacting to Meyer - Schuster generate the pyrazole derivative. Compared with the prior art, the preparation method disclosed by the invention has 91% the advantages of maximum yield, simple operation, mild conditions, high conversion rate, few byproducts and the like, and provides a brand-new synthetic method for construction of pyrazole compounds. (by machine translation)
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Paragraph 0151-0155
(2019/12/02)
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- Mechanistic Studies on the Michael Addition of Amines and Hydrazines to Nitrostyrenes: Nitroalkane Elimination via a Retro-aza-Henry-Type Process
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In this article we report on the mechanistic studies of the Michael addition of amines and hydrazines to nitrostyrenes. Under the present conditions, the corresponding N-alkyl/aryl substituted benzyl imines and N-methyl/phenyl substituted benzyl hydrazones were observed via a retro-aza-Henry-type process. By combining organic synthesis and characterization experiments with computational chemistry calculations, we reveal that this reaction proceeds via a protic solvent-mediated mechanism. Experiments in deuterated methanol CD3OD reveal the synthesis and isolation of the corresponding deuterated intermediated Michael adduct, results that support the proposed slovent-mediated pathway. From the synthetic point of view, the reaction occurs under mild, noncatalytic conditions and can be used as a useful platform to yield the biologically important N-methyl pyrazoles in a one-pot manner, simple starting with the corresponding nitrostyrenes and the methylhydrazine.
- Kallitsakis, Michael G.,Tancini, Peter D.,Dixit, Mudit,Mpourmpakis, Giannis,Lykakis, Ioannis N.
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p. 1176 - 1184
(2018/02/09)
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- Nucleophilic ring-opening reactions of trans-2-aroyl-3-aryl-cyclopropane-1,1-dicarboxylates with hydrazines
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trans-2-Aroyl-3-aryl-cyclopropane-1,1-dicarboxylates when treated with arylhydrazines in refluxing EtOH gave dihydropyrazoles, whereas with hydrazines in refluxing AcOH, they formed cyclopropane-fused pyridazinones. Although in both cases the corresponding hydrazones are formed initially, the former case involves a subsequent 5-exo-tet nucleophilic ring-opening, and the later, a 6-exo-trig nucleophilic attack by the other hydrazone nitrogen. The products are obtained in moderate to excellent yields with complete regio-and diastereoselectivity.
- Sathishkannan, Gopal,Tamilarasan, V. John,Srinivasan, Kannupal
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p. 1400 - 1406
(2017/02/15)
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- Radical Addition of Hydrazones by α-Bromo Ketones to Prepare 1,3,5-Trisubstituted Pyrazoles via Visible Light Catalysis
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A novel efficient tandem reaction of hydrazones and α-bromo ketones is reported for the preparation of 1,3,5-trisubstituted pyrazoles by visible light catalysis. In this system, the monosubstituted hydrazones show wonderful reaction activity with alkyl radicals, generated from α-bromo ketones. A radical addition followed by intramolecular cyclization affords the important pyrazole skeleton in good to excellent yields. This efficient strategy under mild conditions with wide group tolerance provides a potential approach to the 1,3,5-trisubstituted pyrazoles.
- Fan, Xiu-Wei,Lei, Tao,Zhou, Chao,Meng, Qing-Yuan,Chen, Bin,Tung, Chen-Ho,Wu, Li-Zhu
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p. 7127 - 7133
(2016/08/30)
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- Phosphine- and copper-free palladium catalyzed one-pot four-component carbonylation reaction for the synthesis of isoxazoles and pyrazoles
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The palladium catalyzed one-pot synthesis of isoxazoles and pyrazoles from aryl iodides, terminal alkynes, chromium hexacarbonyl and hydroxylamine hydrochloride or aqueous hydrazine solution is described. The Sonogashira carbonylative coupling intermediate was trapped in situ by hydroxylamine hydrochloride or aqueous hydrazine to deliver isoxazoles or pyrazoles, respectively, in high yields. This efficient method proceeds at atmospheric pressure and moderate temperature and does not require the use of copper, phosphine ligands or gaseous carbon monoxide.
- Iranpoor, Nasser,Firouzabadi, Habib,Etemadi-Davan, Elham
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supporting information
p. 837 - 840
(2016/02/05)
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- Visible-light photocatalytic aerobic annulation for the green synthesis of pyrazoles
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A selective and high yielding synthesis of polysubstituted pyrazoles through a VLPC (visible light photoredox catalysis)-promoted reaction of hydrazine with Michael acceptors is reported. The method employs very mild reaction conditions and uses air as the terminal oxidant, which makes the process environmentally benign. Different types of Michael acceptors with various substituents can undergo the reaction to afford corresponding pyrazoles in good to excellent yields. The reaction is proposed to go through VLPC-promoted oxidation of hydrazine to diazene followed by its addition to Michael acceptors, other than the conventional condensation of hydrazine with a carbonyl.
- Ding, Ya,Zhang, Te,Chen, Qiu-Yun,Zhu, Chunyin
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supporting information
p. 4206 - 4209
(2016/09/09)
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- Regioselective synthesis of 1,3,5-Trisubstituted Pyrazoles from N-Alkylated Tosylhydrazones and terminal Alkynes
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An efficient synthesis of 1,3,5-trisubstituted pyrazoles from Nalkylated tosylhydrazones and terminal alkynes was developed. The protocol was applied to a wide range of substrates and demonstrated excellent tolerance to a variety of substituents, includin
- Kong, Yuanfang,Tang, Meng,Wang, Yun
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p. 576 - 579
(2014/04/03)
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- Copper on iron promoted one-pot synthesis of β-aminoenones and 3,5-disubstituted pyrazoles
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The reaction of hydroximoyl chlorides with acetylenes in the presence of a copper on iron bimetallic system leads to β-aminoenones via reductive ring opening of isoxazole intermediates. The valuable β-aminoenone building blocks can be isolated or transformed into pyrazoles with the addition of hydrazine in a straightforward one-pot procedure.
- Kovács, Szabolcs,Novák, Zoltán
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p. 8987 - 8993
(2013/09/24)
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- One-pot synthesis of pyrazoles through a four-step cascade sequence
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A one-pot synthesis of 3,4,5- and 1,3,5-pyrazoles from tertiary propargylic alcohols and para-tolylsulfonohydrazide has been accomplished. The pyrazoles are formed through a four-step cascade sequence, including FeCl 3-catalyzed propargylic substitution, aza-Meyer-Schuster rearrangement, base-mediated 6πelectrocyclization, and thermal [1,5] sigmatropic shift. In this reaction, the 3,4,5- and 1,3,5-pyrazoles are produced selectively according to different substituents in the starting alcohols. A one-pot recipe: The synthesis of 3,4,5- and 1,3,5-pyrazoles from tertiary propargylic alcohols and para-tolylsulfonohydrazide has been accomplished. The pyrazoles are formed through a four-step cascade sequence (see figure), and are produced selectively according to different substituents in the starting alcohols.
- Hao, Lu,Hong, Jun-Jie,Zhu, Jun,Zhan, Zhuang-Ping
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supporting information
p. 5715 - 5720
(2013/06/04)
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- Copper-Catalyzed aerobic intramolecular dehydrogenative cyclization of n,n-disubstituted hydrazones through C sp 3 -H functionalization
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An aerobic activity: The title reaction proceeds through an oxidation/cyclization/aromatization sequence under an atmosphere of O 2 (see scheme; DBU=1,8-diazabicyclo[5.4.0]undec-7-ene, DCE=1,2-dichloroethane, DMS=dimethylsulfide). This coupling
- Zhang, Guangwu,Zhao, Yan,Ge, Haibo
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p. 2559 - 2563
(2013/04/10)
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- HCV NS5A replication complex inhibitors. Part 3
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In a recent disclosure,1 we described the discovery of dimeric, prolinamide-based NS5A replication complex inhibitors exhibiting excellent potency towards an HCV genotype 1b replicon. That disclosure dealt with the SAR exploration of the peripheral region of our lead chemotype, and herein is described the SAR uncovered from a complementary effort that focused on the central core region. From this effort, the contribution of the core region to the overall topology of the pharmacophore, primarily vector orientation and planarity, was determined, with a set of analogs exhibiting 50 in a genotype 1b replicon assay.
- Lopez, Omar D.,Nguyen, Van N.,St. Laurent, Denis R.,Belema, Makonen,Serrano-Wu, Michael H.,Goodrich, Jason T.,Yang, Fukang,Qiu, Yuping,Ripka, Amy S.,Nower, Peter T.,Valera, Lourdes,Liu, Mengping,O'Boyle II, Donald R.,Sun, Jin-Hua,Fridell, Robert A.,Lemm, Julie A.,Gao, Min,Good, Andrew C.,Meanwell, Nicholas A.,Snyder, Lawrence B.
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p. 779 - 784
(2013/02/25)
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- A complementary approach to 3,5-substituted pyrazoles with tosylhydrazones and terminal alkynes mediated by TfOH
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A complementary method for the preparation of 3,5-substituted pyrazoles in moderate to high yields has been explored via TfOH-induced addition of tosylhydrazones to the terminal alkynes. This acid-induced addition procedure might be an operationally safe alternative compared to typical 1,3-dipolar cycloaddition as there is no involvement of diazo compounds.
- Liu, Ping,Xu, Qian-Qian,Dong, Chao,Lei, Xinsheng,Lin, Guo-Qiang
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p. 2087 - 2092
(2012/11/07)
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- A straightforward synthesis of pyrazolines and pyrazoles: Palladium-catalyzed carbonylative vinylation-cyclocondensation reactions of aryl halides
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A novel consecutive one-pot synthesis of pyrazolines and pyrazoles starting from simple aryl halides, styrenes, carbon monoxide, and hydrazines has been established. Palladium-catalyzed carbonylative vinylation of aryl halides gave the corresponding chalcones, which are trapped in situ by addition of hydrazines.
- Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
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p. 4919 - 4924
(2011/10/31)
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- Regioselective synthesis of 1,3,5- and 1,3,4,5-substituted pyrazoles via acylation of N-Boc-N-substituted hydrazones
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Acylation of N-Boc-N-methylhydrazones followed by TFA treatment affords regioselective access to substituted pyrazoles. Both regioisomers of 1-methyl-3,5-disubstituted-1H-pyrazoles can be selectively obtained. This procedure can also be employed for the r
- Tinarelli, Alessandro,Righi, Paolo,Rosini, Goffredo,Andreotti, Daniele,Profeta, Roberto,Spada, Simone
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p. 612 - 617
(2011/03/19)
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- The preparation of substituted pyrazoles from β,β-dibromo-enones by a tandem condensation/Suzuki-Miyaura cross-coupling process
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Two consecutive tandem processes are described for the regioselective, two-step synthesis of 1,3,5-trisubstituted pyrazoles from α- hydroxyketones. The first, a tandem MnO2-mediated oxidation/Ramirez olefination reaction, provides a facile route to β,β-dibromo-enones. These valuable 1,3-dicarbonyl synthons can then be converted into 1,3,5-trisubstituted pyrazoles via a second tandem hydrazine condensation/Suzuki-Miyaura cross-coupling reaction. Using these procedures, a range of aryl and alkyl α-hydroxyketones have been transformed regioselectively into 1,3,5-trisubstituted pyrazoles. Georg Thieme Verlag Stuttgart.
- Beltrán-Rodil, Sandra,Edwards, Michael G.,Pugh, David S.,Reid, Mark,Taylor, Richard J.K.
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body text
p. 602 - 606
(2010/09/18)
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- Multi-Step synthesis by using modular flow reactors: The preparation of Yne-Ones and their use in heterocycle synthesis
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"Chemical Equation Presented" Multi-step in flow: The palladium-catalysed acylation of terminal alkynes for the synthesis of yne-ones as well as their further transformation to various heterocycles in a continuous-flow mode is presented. Furthermore, an extension of the simple flow configuration that allows for easy batch splitting and the generation of a heterocyclic library is described (see scheme).
- Baxendale, Ian R.,Schou, Seren C.,Sedelmeier, Joerg,Ley, Steven V.
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scheme or table
p. 89 - 94
(2010/03/03)
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- A general and convenient palladium-catalyzed carbonylative sonogashira coupling of aryl bromides
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Convenient carbonylations: An efficient methodology for the carbonylative Sonogashira reaction of aryl bromides has been developed (see scheme). Contrary to known procedures, inexpensive aryl bromides can be applied as substrates to give the desired compounds in moderate to good yields (47-88%).
- Wu, Xiao-Feng,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 12104 - 12107
(2011/02/25)
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- One-pot four-component reaction for the generation of pyrazoles and pyrimidines
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The palladium-catalysed four-component coupling of a halide, terminal alkyne, molybdenum hexacarbonyl and either a hydrazine or amidine has been shown to be an efficient method for the construction of highly substituted pyrazoles and pyrimidines, respectively, in a one-pot process. Georg Thieme Verlag Stuttgart.
- Stonehouse, Jeffrey P.,Chekmarev, Dmitriy S.,Ivanova, Natalya V.,Lang, Stuart,Pairaudeau, Garry,Smith, Neal,Stocks, Michael J.,Sviridov, Sergey I.,Utkina, Lyubov M.
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p. 100 - 104
(2008/09/21)
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- Reactions of lithium silylcuprates with pyrazolium and indazolium salts
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Although pyrazolium salts have been shown to be unreactive toward lithium carbocuprates, these substrates were opened by lithium silylcuprate reagents to give versatile N-silylated β-enaminoimines stabilized by coordination of the silyl group with both ni
- Gonzalez-Nogal, Ana M.,Calle, Mariola,Cuadrado, Purificacion
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p. 6089 - 6096
(2008/09/17)
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- Synthesis of pyrazoles by a one-pot tandem cyclization-dehydrogenation approach on Pd/C/K-10 catalyst
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A novel one-pot synthesis of substituted pyrazoles from chalcones and hydrazines via a tandem cyclization-dehydrogenation approach is described. This process is based on the use of a bifunctional noble-metal/solid-acid catalyst, Pd/C/K-10 montmorillonite
- Landge, Shainaz M.,Schmidt, Allison,Outerbridge, Verona,T?r?k, Béla
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p. 1600 - 1604
(2008/02/05)
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- Ring-closure reactions through intramolecular substitution of thiophenoxide by oxygen and nitrogen nucleophiles: Simple stereospecific synthesis of 4,5-dihydroisoxazoles and 4,5-dihydropyrazoles
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A new and simple method for the stereospecific synthesis of 3,5-disubstituted-4,5-dihydro-isoxazoles (chiral isoxazolines) from readily available oximes of chiral Michael adducts of thiophenol to chalcones is reported. An analogous reaction with the N-arylhydrazones of the Michael adduct gave nonracemic 1-(aryl)-3,5-diphenyl-4,5-dihydro-1H-pyrazoles (chiral pyrazolines), but these products are configurationally unstable. The key step of the synthesis is the ring-closure reaction, which occurs by a stereospecific intramoleculer nucleophilic substitution of thiophenoxide.
- Zielinska-B?ajet, Mariola,Kowalczyk, Rafa?,Skarzewski, Jacek
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p. 5235 - 5240
(2007/10/03)
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- One-pot construction of pyrazoles and isoxazoles with palladium-catalyzed four-component coupling
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(Chemical Equation Presented) Four-component coupling of a terminal alkyne, hydrazine (hydroxylamine), carbon monoxide, and an aryl iodide furnishes pyrazole or isoxazole derivatives in the presence of a palladium catalyst. The reaction proceeds at room temperature and an ambient pressure of carbon monoxide in an aqueous solvent system.
- Mohamed Ahmed, Mohamed S.,Kobayashi, Kei,Mori, Atsunori
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p. 4487 - 4489
(2007/10/03)
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- A new and a convenient route to enaminones and pyrazoles
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A new method has been developed for the regioselective preparation of enaminones and pyrazoles from 1,3-diketonatoboron difluorides. The reactions proceed smoothly under mild reaction conditions, producing enaminones and pyrazoles in high yields.
- Stefane, Bogdan,Polanc, Slovenko
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- Regioselective synthesis of polysubstituted pyrazoles and isoxazoles
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A regioselective synthesis has been developed for the preparation of unsymmetrical 1,3,5-triaryl-4-alkylpyrazolines and -pyrazoles by treatment of α-benzotriazolyl-α,β-unsaturated ketones with monosubstituted hydrazines followed by alkylation at the 4-position of the pyrazoline ring. Reaction of α-benzotriazolyl-α,β-unsaturated ketones with hydroxylamine gives 3,5-disubstituted isoxazoles regioselectively.
- Katritzky,Wang,Zhang,Voronkov,Steel
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p. 6787 - 6791
(2007/10/03)
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- Process for preparing N-substituted pyrazoles
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A process for the preparation of an N-alkyl- or N-phenylalkyl-substituted pyrazole I by reacting the corresponding N-unsubstituted pyrazole II with an alcohol III of the formula R1 --OH where R1 is the same alkyl or phenylalkyl group to be added to the unsubstituted nitrogen group --NH-- of the pyrazole reactant. Both of the reactants, i.e. the pyrazole II and alcohol III compounds, are catalytically reacted in the liquid phase in a molar ratio of from 0.001:1 to 1:1, at temperatures of 50°-400° C. and under a subatmosheric pressure of from 0.8 bar up to a superatmospheric pressure of 250 bar. The catalyst required for this liquid phase reaction is selected as being at least one or more non-heterogeneous acid catalysts, their alkyl esters or their acid anhydrides.
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- Palladium(II) coordination and cyclometallated complexes derived from 3- and 5-aryl-substituted pyrazoles
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Palladium(II) coordination complexes of nine 3- or 5-arylpyrazoles (phenyl, 2-bromophenyl, or 3-methoxyphenyl), as well as of 3,5-diphenylpyrazole, are reported.A cis-trans mixture of isomers is found in the case of 3-aryl-1-methylpyrazoles, the cis-isomers being transformed into trans by heating.Only trans isomers are isolated with the other ligands.Cyclopalladation of 3-aryl-1-methylpyrazoles can be performed with palladium(II) acetate, and the resultant μ-acetate bridged dimers can be transformed into μ-chloro bridged dimers or acetylacetonate monomers.The structures of the complexes have been characterized by 1H- and 13C-NMR spectroscopy.
- Alonso, M. T.,Juanes, O.,Mendoza, J. de,Rodriguez-Ubis, J. C.
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p. 335 - 347
(2007/10/02)
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- PROTOLYTIC AND COMPLEXING PROPERTIES OF PYRAZOLES. PART III. 1-PHENYLPYRAZOLE, 3(5)-PHENYLPYRAZOLE, 3,5-DIPHENYLPYRAZOLE, 1-METHYL-3,5-DIMETHYLPYRAZOLE, AND 1,3,5-TRIPHENYLPYRAZOLE
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The pK1 and pK2 values of pyrazoles under study have been determined and studies have been carried out on complexation reaction with Cu(II) ions.Solid complexes with Cu(NO3)2 have been obtained, of CuL2(NO3)2 type.A discussion is given on the effect of substituents on protolytic and complexing properties of N-substituted pyrazoles.
- Kostka, Krzysztof,Strawiak, Marian M.
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p. 647 - 651
(2007/10/02)
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- 1,3-Dipolar Cycloadditions, 91. The Chemistry of N-Methyl-C-phenylnitrilimine
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The treatment of N'--N-methylhydrazinium bromide, accessible by bromination of benzaldehyde-N-methylhydrazone, with triethylamine furnishes the title compound; this method is superior to the thermolysis and photolysis of 2-methyl-5-phe
- Fliege, Werner,Grashey, Rudolf,Huisgen, Rolf
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p. 1194 - 1214
(2007/10/02)
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- N-Methyl-N-(phenylsulfonyl)benzohydrazonoyl Chloride as a Potential Intermediate for Nitrogen-heterocycles. Preparation of 1-Methyl-3-phenyl-1H-1,2,4-triazoles and -pyrazoles
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3,5-Disubstituted 1-methyl-1H-1,2,4-triazoles and -pyrazoles were obtained in good to moderate yields by the reaction of N-methyl-N-(phenylsulfonyl)benzohydrazonoyl chloride with nitriles and with acetylenes in the presence of aluminum chloride.The triazo
- Ito, Suketaka,Tanaka, Yumo,Kakehi, Akikazu,Fukuyama, Toshihiko,Osawa, Nobuo,Sayo, Noboru
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p. 545 - 548
(2007/10/02)
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- Reaction of pyrylium salts with hydrazine and methylhydrazine. Concerning the scope of the 1,2(4H)-diazepine synthesis
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The reaction of pyrylium salts 1a-e with methylhydrazine gives pyrazolines(2), pyrazoles(3), pyridines(4), 1,2-diazepine(5), and N-methylaminopyridinium salts(6).Product composition has been studied as a function of pyrylium salt counter anion, concentration of methylhydrazine, and conditions of the reaction(Table 1).Pyridines(4), and 1,2-diazepines(5) are minor components, the major products being the pyrazolines(2) and pyrazoles(3).The reactions of more unusual pyrylium salts(1f-i, 8a, 9a, 9c, and 11a) with hydrazine have been shown to provide 1,2(4H)-diazepines(10, 12-15) and N-aminopyridinium salts(8b, 9b) (Table 2), the nature of the product apparently depending on the absence or presence of 2-methyl substitution respectively in the starting pyrylium salts.
- Harris, D. J.,Kan, G. Y.-P.,Tschamber, T.,Snieckus, V.
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p. 494 - 500
(2007/10/02)
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- 1,2-Dimethyl-3,5-diphenylpyrazolium-2,2-dichloropropionate
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The invention is novel compositions containing a pyrazolium salt and a polyhalocarboxylic acid, an alkali metal or alkaline earth metal polyhalocarboxylate salt useful in the control of wild oats and other undesirable grass plants. The invention includes a herbicidal salt of the pyrazolium cation and the polyhalocarboxylate anion.
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- Herbicidal combinations
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This invention is (1) synergistic combinations of a 1,2-dialkyl-3,5-diphenylpyrazolium salt and a 2,4-dichlorophenoxy acetic acid or the salts and esters thereof, or 4-chloro-2-methylphenoxy acetic acid or the salts or esters thereof useful as herbicides; (2) a salt of a 1,2-dialkyl-3,5-diphenylpyrazolium cation and certain halophenoxy acetate anions useful as herbicides and (3) the synergistic combination of 1, above, with the salt of 2, above, present.
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- Catalytic dehydrogenation process for the preparation of 3,4,5-trisubstituted pyrazoles
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There is provided a process for the preparation of 3,5-disubstituted pyrazoles which involves: A. the reaction of a methyl ketone, such as acetophenone or an appropriate derivative thereof, with an appropriate aldehyde, such as benzaldehyde in the presence of base to form a 1,3-disubstituted α,β-unsaturated ketone, such as chalcone or a substituted chalcone, B. the acidification of said α,β-unsaturated ketone, followed by treatment of the acidified reaction mixture with hydrazine to form a disubstituted pyrazoline, and C. the catalytic dehydrogenation of said pyrazoline to yield the desired 3,5-disubstituted pyrazole.
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- Catalytic dehydrogenation process for the preparation of 3,5-disubstituted pyrazoles
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There is provided a process for the preparation of 3,5-disubstituted pyrazoles which involves: A. the reaction of a methyl ketone, such as acetophenone or an appropriate derivative thereof, with an appropriate aldehyde, such as benzaldehyde in the presence of base to form a 1,3-disubstituted α,β-unsaturated ketone, such as chalcone or a substituted chalcone, B. the acidification of said α,β-unsaturated ketone, followed by treatment of the acidified reaction mixture with hydrazine to form a disubstituted pyrazoline, and C. the catalytic dehydrogenation of said pyrazoline to yield the desired 3,5-disubstituted pyrazole.
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