- Transformations of 4,9-Dimethyl-2,3,7,8-tetra-azatetracyclo4,1206,10>trideca-1,6-diene , a Bishydrazone having Two Bridgehead Double Bonds
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Reduction of the anti-Bredt bishydrazone 4,9-dimethyl-2,3,7,8-tetra-azatetracyclo4,1206,10>trideca-1,6-diene with lithium aluminium hydride-aluminium chloride or by catalytic hydrogenation gives the bishydrazine 1,6-dimethyl-2,3,7,8-tetra-azatetracyclo4,1206,10>tridecane, but reaction with either lithium aluminium hydride or aluminium chloride gives dihydropyrazoles by ring cleavage.
- Mellor, John M.,Pathirana, Ranjith
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- Cross-conjugated Mesomeric Betaines: 3-Oxopyrazolopyrazol-8-ylium-1-olate
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Carbon suboxide and pyrazole led to the title system, the parent member of a group of cross-conjugated mesomeric betaines: with 3,5-dimethylpyrazole, the corresponding 5,7-dimethyl derivative was obtained, this being sufficiently stable for physical and chemical characterization.
- Potts, Kevin T.,Murphy, Peter
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- Synthesis of quinoxaline, benzimidazole and pyrazole derivatives under the catalytic influence?of biosurfactant-stabilized iron nanoparticles in water
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Abstract: We have reported the synthesis, characterization, and catalytic applications of amorphous iron nanoparticles (FeNPs) using aqueous leaves extract of renewable natural resource Boswellia serrata plant. Synthesized FeNPs were stabilized in situ by the addition of aqueous pod extracts of Acacia concinna as a biosurfactant (pH 3.11). The structural investigation of biosynthesized nanoparticles was performed using UV–visible spectroscopy, X-ray diffraction analysis, selected area electron diffraction, energy-dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and BET analysis. The FeNPs were amorphous in nature with average particle size ~ 19?nm and successfully employed as heterogeneous catalyst for the synthesis of quinoxaline, benzimidazole, and pyrazole derivatives in aqueous medium at ambient conditions. The FeNPs could be recycled up to five times with modest change in the catalytic activity. Graphic abstract: [Figure not available: see fulltext.].
- Arde, Satyanarayan M.,Patil, Audumbar D.,Mane, Ananda H.,Salokhe, Prabha R.,Salunkhe, Rajashri S.
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- Application of Fe3O4@SiO2@sulfamic acid magnetic nanoparticles as recyclable heterogeneous catalyst for the synthesis of imine and pyrazole derivatives in aqueous medium
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Sulfamic acid supported on Fe3O4@SiO2 superpara magnetic nanoparticles was successfully applied as a recyclable solid acid catalyst with a large density of sulfamic acid groups for the synthesis of pyrazole derivatives, an important class of potentially bioactive compounds. The products are obtained in high yield from the one-pot reaction procedure involving dicarbonyl compounds and hydrazines/hydrazides. This new method totally avoids the use of toxic or expensive solvents and organic acids in this reaction.
- Zakerinasab,Nasseri,Hassani,Samieadel
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- Hydrotrope: Green and rapid approach for the catalyst-free synthesis of pyrazole derivatives
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An efficient synthesis of pyrazole derivatives by condensation of 1,3-diketone and hydrazines/hydrazides has been achieved in aqueous hydrotropic solution under catalyst-free conditions within a very short time. The present protocol is beneficial as it includes mild reaction conditions, shorter reaction times, use of universal solvent water, which avoids volatile organic solvents, high yields of products, and being environmentally friendly.
- Barge, Madhuri,Kamble, Santosh,Kumbhar, Arjun,Rashinkar, Gajanan,Salunkhe, Rajashri
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- PEG-SO3H as a mild, efficient and green catalytic system for the synthesis of pyrazole derivatives in aqueous medium
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A versatile, alternative and environmentally benign strategy for the synthesis of a series of pyrazoles has been successfully performed in water using PEG-SO3H as an acidic catalyst. The products are obtained in high yield from the one-pot reaction procedure involving dicarbonyl compounds and hydrazines/hydrazides. This new method totally avoids the use of organic acids and toxic or expensive solvents in this reaction. The catalyst is waste-free, easily prepared, and efficiently re-used.
- Nasseri,Alavi,Zakeri Nasab
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- Ring-ring tautomerism in 1,3-alkanoylhydrazonoximes of acetylacetone
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The coexistence in solution of tautomeric isoxazoline and pyrazoline forms of 1,3-alkanoylhydrazonoxime of acetylacetone has been detected and investigated by 1H and 13C NMR spectroscopic methods. The compounds indicated eliminate hydroxylamine under the action of acid catalysts, forming 1-acyl-3,5-dimethylpyrazoles.
- Ershov,Dobrodumov
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- Copper-catalyzed C–N cross-coupling of arylboronic acids with N-acylpyrazoles
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A copper-catalyzed C–N bond forming reaction of arylboronic acids and N-acylpyrazoles was developed. This procedure used N-acetyl protected pyrazoles as starting material instead of free pyrazoles (NH). The reaction worked under neutral conditions and did not require any base or ligand. The reaction showed good functional group tolerance.
- Zhang, Jin,Jia, Run-Ping,Wang, Dong-Hui
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supporting information
p. 3604 - 3607
(2016/07/21)
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- An efficient practical chemo-enzymatic protocol for the synthesis of pyrazoles in aqueous medium at ambient temperature
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An expeditious oxidative cyclocondensation reaction of hydrazines/hydrazides with 1,3-dicarbonyl compound was efficiently developed in aqueous medium using Saccharomyces cerevisae (baker's yeast) as a whole cell biocatalyst at room temperature. The method has been assigned using green chemistry measures and found to give a range of N-substituted pyrazoles with moderate to excellent yields (70-92%). The reaction progress was monitored by gas chromatography.
- Mane, Ananda,Salokhe, Prabha,More, Pallavi,Salunkhe, Rajashri
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- Cellulose sulfuric acid as a bio-supported and efficient solid acid catalyst for synthesis of pyrazoles in aqueous medium
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A convenient and practical method was described for the regioselective synthesis of pyrazoles from hydrazines/hydrazides and 1,3-dicarbonyl compounds via the Knorr synthesis in water with cellulose sulfuric acid (CSA) as a biopolymer-based solid acid catalyst. Various hydrazines and hydrazides were reacted with 1,3 diketones and the desired pyrazoles were obtained in high yields. The reaction of less reactive hydrazines with 1,3-dicarbonyl compounds stopped at the corresponding hydrazone derivatives. Hydrazides were employed with β-ketoester, and imine adducts were the only isolated product. Simple isolation of products, mild reaction conditions, reusability of solid acid catalysts and short reaction times are advantages of this green procedure. This journal is
- Nasseri, Mohammad Ali,Salimi, Mehri,Esmaeili, Abbas Ali
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p. 61193 - 61199
(2015/02/19)
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- Mixing with microwaves: Solvent-free and catalyst-free synthesis of pyrazoles and diazepines
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A simple and facile condensation of hydrazines/hydrazides and diamines with 1,3-diketones/β-ketoester leads to the preparation of pyrazoles and diazepines in high yields. This eco-friendly protocol is accelerated by microwave heating and efficiently carried out without any reaction solvent or catalyst in as little as 5 min.
- Vaddula, Buchi Reddy,Varma, Rajender S.,Leazer, John
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supporting information
p. 1538 - 1541
(2013/03/14)
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- Zn[(l)proline]2 in water: A new easily accessible and recyclable catalytic system for the synthesis of pyrazoles
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Zn[(l)proline]2 has been found to be an efficient catalyst for the synthesis of pyrazole derivatives in pure water at room temperature. Reaction afforded moderate to excellent yield within a lesser time. Various pyrazoles which could not be prepared by other methods can be easily prepared by this method efficiently. Catalyst exhibits recyclability up to five runs. Hence our present protocol is economical and clean comprise of green reagent, solvent and catalyst.
- Kidwai, Mazaahir,Jain, Arti,Poddar, Roona
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experimental part
p. 1939 - 1944
(2011/06/19)
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- Room-temperature synthesis of pyrazoles, diazepines, β-enaminones, and β-enamino esters using silica-supported sulfuric acid as a reusable catalyst under solvent-free conditions
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Silica-supported sulfuric acid (H2SO4·SiO2) has been utilized as a heterogeneous recyclable catalyst for a highly efficient regio- and chemoselective condensation of hydrazines/hydrazides, diamines, and primary amines with various β-dicarbonyl compounds at room temperature to afford pyrazoles, diazepines, and β-enaminones/β-enamino esters under solvent-free conditions within 5-15 min. Copyright Taylor & Francis Group, LLC.
- Chen, Xiang,She, Jin,Shang, Zhi-Cai,Wu, Jun,Zhang, Peizhi
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experimental part
p. 947 - 957
(2009/09/06)
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- Greener and rapid access to bio-active heterocycles: room temperature synthesis of pyrazoles and diazepines in aqueous medium
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An expeditious room temperature synthesis of pyrazoles and diazepines by condensation of hydrazines/hydrazides and diamines with various 1,3-diketones is described. This greener protocol was catalyzed by polystyrene supported sulfonic acid (PSSA) and proceeded efficiently in water in the absence of any organic solvent within 1-2 min.
- Polshettiwar, Vivek,Varma, Rajender S.
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p. 397 - 400
(2008/09/17)
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- Synthesis of pyrazoles, diazepines, enaminones, and enamino esters using 12-tungstophosphoric acid as a reusable catalyst in water
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12-Tungstophosphoric acid (H3PW12O40) is found to be an efficient and recyclable catalyst in promoting a chemo- and regioselective condensation of hydrazines/hydrazides, diamines, and primary amines with various 1,3-dicarbonyl compounds in pure water at room temperature to afford pyrazoles, diazepines, and enaminones/enamino esters, respectively, in high yields. Georg Thieme Verlag Stuttgart.
- Chen, Xiang,She, Jin,Shang, Zhicai,Wu, Jun,Wu, Haifeng,Zhang, Peizhi
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experimental part
p. 3478 - 3486
(2009/05/09)
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- Enantioselective enol lactone synthesis under double catalytic conditions
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(Chemical Equation Presented) The reaction of dimedone with 1-(2-alkenoyl)-4-bromo-3,5-dimethylpyrazoles in THF, catalyzed by catalytic amounts of both DBFOX/Ph-nickel-(II) perchlorate trihydrate and 2,2,6,6-tetramethylpiperidine, in the presence of acetic anhydride in THF produces the corresponding enol lactones in high enantioselectivities through enantioselective Michael additions followed by cyclization with removal of the pyrazole auxiliary. Other related nucleophile precursors can be successfully applied in the enantioselective enol lactone synthesis under the double catalytic conditions.
- Itoh, Kennosuke,Hasegawa, Masayuki,Tanaka, Junji,Kanemasa, Shuji
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p. 979 - 981
(2007/10/03)
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- Resolution of secondary alcohols using 2-acyl-3-phenyl-l-menthopyrazoles as enantioselective acylating agents
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The chelation of AlCl3 with N-acylpyrazoles leads to structural fixation of the acyl moiety and an acceleration in the rate of acylation of secondary alcohols. The chiral environment of the fixed acyl moiety of 2-acyl-3-phenyl-l-menthopyrazole 2 causes diastereofacial selectivity in the reaction with secondary alcohols, and thus 2 behaves as an enantioselective acylating agent. By the use of 2.4 molar equivalents of racemic 1-phenylethanol 3a, 2-acetyl-3-phenyl-l-menthopyrazole 2a afforded (S)-1-phenylethyl acetate (S)-4aa enantioselectively and unreacted 3a was recovered with (R)-configuration. Furthermore, the inverse configurational preferences were observed to give (R)-4aa and (S)-3a by the addition of strongly basic amines, which sometimes behaved as catalysts for enolate formation from 2 and AlCl3. These dramatic changes in stereoselective preference should be useful properties of 2-acyl-3-phenyl-l-menthopyrazole 2 as an enantioselective acylating agent.
- Kashima, Choji,Mizuhara, Saori,Miwa, Yohei,Yokoyama, Yukihiro
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p. 1713 - 1719
(2007/10/03)
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- Preparation of β-substituted γ-keto esters by the grignard reaction on N-acylpyrazoles
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Various γ-keto esters were prepared by either the alcoholysis of N-(4-oxoalkanoyl)pyrazoles or the Grignard replacement of pyrazole moiety of 4-(N-pyrazolyl)-4-oxoalkanoic esters. By using 3-phenyl-ι-menthopyrazole as a chiral auxiliary, β-substituted γ-keto esters were enantioselectively obtained.
- Kashima, Choji,Shirahata, Yoshie,Tsukamoto, Yoshihiro
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p. 309 - 317
(2007/10/03)
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- Reactions of β-aminoenones with acetylhydrazine, semicarbazide and methoxycarbonylhydrazine. Synthesis of 1-acetyl-, 1-carboxamide- or methyl 1- carboxylated pyrazole derivatives
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Acetylhydrazine, semicarbazide and methoxycarbonylhydrazine react with β-aminoenones to give regioselectively the corresponding N-acetyl- or N- carboxypyrazole derivatives. The reaction are highly regioselective and occurs via 5-hydroxypyrazolines which in several case can be isolated and characterized.
- Alberola, Angel,Calvo, Luis,Ortega, Alfonso Gonzalez,Sadaba, M. Luisa,Sanudo, M. Carmen,Granda, Santiago Garcia,Rodriguez, Elena Garcia
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p. 2675 - 2686
(2007/10/03)
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- Recyclization of Pyrimidin-2(1H)-one into 2-Isoxazoline and 2-Pyrazoline
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A reaction of 1-aryl-4,6-dimethylpyrimidin-2(1H)-ones with hydroxylamine and acetylhydra-zine leads to previously unknown 5-N-arylcarbamoylamino derivatives of 3,5-dimethyl-2-isoxazoline and 2-pyrazoline. The structure of the compounds obtained was confirmed by 1H and 13C NMR as well as independent synthesis by reacting phenyl isocyanate with 5-amino-3,5-dimethyl-2-isoxazoline and 1-acetyl-2-pyrazoline.
- Ershov,Gindin,Gribanov
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p. 388 - 391
(2007/10/03)
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- The preparation of N-acetylpyrazoles and their behavior toward alcohols
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According to four different methods, various types of n-acylpyrazoles were prepared from the corresponding pyrazoles and carboxylic acids or their acid chlorides. Although A-acylpyrazoles were inert to alcohols under neutral or weakly basic conditions, th
- Kashima,Harada,Kita,Fukuchi,Hosomi
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