- Oxidative decarboxylation of benzilic acid by a biomimetic iron(II) Complex: Evidence for an iron(IV)-oxo-hydroxo oxidant from O2
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O2-dependent transformation: An iron(II)-benzilate complex of a tridentate N3 donor ligand reacts with O2 to undergo oxidative decarboxylation. Cyclohexene is selectively converted into cis-cyclohexane-1,2- diol in the reaction. Copyright
- Paria, Sayantan,Que Jr., Lawrence,Paine, Tapan Kanti
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- A novel synthesis of 5-aryl-3-phenylpyrazole from 2-aryl-3-benzoyl-1,1- cyclopropanedicarbonitrile and hydrazine
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A new process for synthesis of 5-aryl-3-phenylpyrazole is achieved. The regioselective ring-opening reaction of 2-aryl-3-benzoyl-1,1- cyclopropanedicarbonitrile with hydrazine plays a crucial role in the described process.
- Ren, Zhongjiao,Cao, Weiguo,Chen, Jie,Wang, Yu,Ding, Weiyu
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- New mononuclear Pd(II) complexes of sterically hindered bispyrazolylmethanes
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Three new palladium(II) complexes incorporating the bispyrazolylmethane core have been synthesised and fully characterised in the solution and solid state. Single crystal X-ray studies revealed almost complete blocking of the upper face of the palladium ion by the substituents at the 3- and 5-positions of the pyrazole rings. Preliminary screening of the complexes for palladium(II) mediated catalysis revealed good catalytic activity for the Heck coupling reaction.
- Jones, Michael W.,Adlington, Robert M.,Baldwin, Jack E.,Le Pevelen, Delphine D.,Smiljanic, Nicolas
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- A novel one-pot method for the preparation of pyrazoles by 1,3-dipolar cycloadditions of diazo compounds generated in situ
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A convenient one-pot procedure for the preparation of pyrazoles by 1,3-dipolar cycloaddition of diazo compounds generated in situ has been developed. Diazo compounds derived from aldehydes were reacted with terminal alkynes to furnish regioselectively 3,5-disubstituted pyrazoles. Furthermore, the reaction of N-vinylimidazole and diazo compounds derived from aldehydes gave exclusively 3-substituted pyrazoles in a one-pot process.
- Aggarwal, Varinder K.,De Vicente, Javier,Bonnert, Roger V.
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- Stereochemistry of Base-catalysed Addition of Methyl Mercaptoacetate to Acetylenic Ketones and Esters. Effects of Activating Groups and Solvents
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Piperidine-catalysed addition of methyl mercaptoacetate to benzoyl- and p-chlorobenzoyl-phenylacetylenes in ethanol gave the corresponding (Z)-1-aryl-3-(methoxycarbonylmethylthio)-3-phenyl-2-propen-1-one.However, p-anisoylphenylacetylene gave a mixture of (Z)- and (E)-3-(methoxycarbonylmethylthio)-1-(p-methoxyphenyl)-3-phenyl-2-propen-1-ones in the ratio of 4:1.This ratio was completely inverted when the latter addition was carried out in dry benzene.Rationalisation of these results is presented which depends on the effect of activating groups and solvents on thestereochemistry of addition.Piperidine-catalysed addition of methyl mercaptoacetate to methyl phenylpropiolate in ethanol gave methyl (Z)-3-(methoxycarbonylmethylthio)cinnamate.Hydrazine hydrate converted some of the above mono-adducts into some pyrazole derivatives.
- Basyouni, Mohamed Nabih,Omar, Mohamed Tawfik,Ghali, Edwar Amin
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- Hexacarbonylmolybdenum-Induced N-N Bond Cleavage of Pyrazoles. Conversion of 1-Acylpyrazoles to Pyrimidines
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-induced reactions of 1-acyl-3,5-disubstituted pyrazoles underwent N-N bond cleavage and subsequent cyclocondensation to give pyrimidines as well as deacylation to give 3,5-disubstituted pyrazoles.Under similar conditions, 1,3,5-trisubstituted pyrazoles, which have no electron-withdrawing substituent on N1, gave no product, except for the starting materials.
- Nitta, Makoto,Hamamatsu, Tatsuo,Miyano, Hiroyuki
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- Reactivity studies of (η6-arene)ruthenium dimeric complexes towards pyrazoles: Isolation of amidines, bis pyrazoles and chloro bridged pyrazole complexes
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The complex [(η6-p-cymene)Ru(μ-Cl)Cl]2 1 reacts with pyrazole ligands (3a-g) in acetonitrile to afford the amidine derivatives of the type [(η6-p-cymene)Ru(L) (3,5-HRR′pz)](BF4)2 (4a-f), where L = {HN = C(Me)3,5-RR′pz}; R, R′ = H (4a); H, CH3, CH6H5 (4c); CH3, C6 H5 (4d) OCH3 (4e); and OC2H5 (4f), respectively. The ligand L is generated in situ through the condensation of 3,5-HRR′pz with acetonitrile under the influence of [(η6-p-cymene)RuCl2]2. The complex [(η6-C6Me6)Ru(μ-Cl)Cl] 2 2 reacts with pyrazole ligands in acetonitrile to yield bis-pyrazole derivatives such as [(η6-C6 Me6)Ru (3,5-HRR′pz)2Cl](BF4) (5a b), where R, R′ = H (5a); H, CH3 (5b) as well as dimeric complexes of pyrazole substituted chloro bridged derivatives [{(η6-C6Me6)Ru(μ-Cl) (3,5-HRR′pz)}2](BF4)2 (5c-g), where R, R′ = CH3 (5c); C6H5 (5d); CH3, C6H5 (5e); OCH3 (5f); and OC2H5 (5g), respectively. These complexes were characterized by FT-IR and FT-NMR spectroscopy as well as analytical data. The molecular structures of representative complexes [(η6-C6Me6)Ru {3(5)-Hmpz}2Cl]+ 5b, [(η6- C6Me6)Ru(μ-Cl)(3,5-Hdmpz)]2 2+ 5c and [(η6-C6Me6) Ru(μ-Cl){3(5)Me,5(3)Ph-Hpz}]22+ 5e were established by single crystal X-ray diffraction studies.
- Govindaswamy,Mozharivskyj, Yurij A.,Kollipara, Mohan Rao
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- Fragmenlt Recombination Design, Synthesis, and Safener Activity of Novel Ester-Substituted Pyrazole Derivatives
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Fenoxaprop-p-ethyl (FE), a type of acetyl-CoA carboxylase (ACCase) inhibitor, has been extensively applied to a variety of crop plants. It can cause damage to wheat (Triticum aestivum) even resulting in the death of the crop. On the prerequisite of not reducing herbicidal efficiency on target weed species, herbicide safeners selectively protect crops from herbicide injury. Based on fragment splicing, a series of novel substituted pyrazole derivatives was designed to ultimately address the phytotoxicity to wheat caused by FE. The title compounds were synthesized in a one-pot way and characterized via infrared spectroscopy, 1H nuclear magnetic resonance, 13C nuclear magnetic resonance, and high-resolution mass spectrometry. The bioactivity assay proved that the FE phytotoxicity to wheat could be reduced by most of the title compounds. The molecular docking model indicated that compound IV-21 prevented fenoxaprop acid (FA) from reaching or acting with ACCase. The absorption, distribution, metabolism, excretion, and toxicity predictions demonstrated that compound IV-21 exhibited superior pharmacokinetic properties to the commercialized safener mefenpyr-diethyl. The current work revealed that a series of newly substituted pyrazole derivatives presented strong herbicide safener activity in wheat. This may serve as a potential candidate structure to contribute to the further protection of wheat from herbicide injury.
- Fu, Ying,Gao, Shuang,Jia, Ling,Ye, Fei,Zhang, Yuan-Yuan,Zhao, Li-Xia
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- Synergistic antifungal effect of cyclized chalcone derivatives and fluconazole against Candida albicans
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The occurrence of invasive fungal diseases, particularly in immunocompromised patients, is life-threatening and increases the economic burden. The rising problem of multi-drug resistance is becoming a major concern for clinicians. In addition, a repertoire of antifungal agents is far less in number than antibacterial drugs. To combat these problems, combination therapy has gained a lot of interest. We previously reported the synergistic interaction of some mono- and bis-dihydropyrimidinone and thione derivatives with fluconazole and amphotericin B for combination antifungal therapy. In this study we used the same approach and synthesized different azole and non-azole derivatives of mono-(M) and bis-(B) chalcones and evaluated their antifungal activity profile alone and in combination with the most commonly used antifungal drug-fluconazole (FLC)-against seven FLC susceptible and three FLC resistant clinically isolated Candida albicans strains. Based on the minimum inhibitory concentration results, the bis-derivatives showed lower MIC values compared to their mono-analogues. Both fractional inhibitory concentration index and isobologram results revealed mostly synergistic, additive or indifferent interactions between the tested compounds and FLC against different Candida isolates. None of the tested compounds showed any effect on energy dependent R6G efflux, revealing that they do not reverse the mechanism of drug efflux. However, surprisingly, these compounds profoundly decreased ergosterol biosynthesis and showed down regulation of ERG11 gene expression, which is the possible mechanism of reversal of azole drug resistance by these compounds. These results provide a platform for further research to develop pyrimidinone/thione ring containing compounds as promising new antifungal agents, which could be used in antifungal combination therapy.
- Ahmad, Aijaz,Wani, Mohmmad Younus,Patel, Mrudula,Sobral, Abilio J.F.N.,Duse, Adriano G.,Aqlan, Faisal Mohammed,Al-Bogami, Abdullah Saad
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- Synthesis of [3,3′(4H,4′H)-Bi-2H-1,3-oxazine]-4,4′-diones and their hydrolysis
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The [3,3′(4H,4′H)-bi-2H-1,3-oxazine]-4,4′-diones 3a-3i were obtained by [2+4] cycloaddition reactions of furan-2,3-diones 1a-1c with aromatic aldazines 2a-2d (Scheme 1). So, new derivatives of bi-2H-1,3-oxazines and their hydrolysis products, 3,5-diaryl-1H-pyrazoles 4a-4c (Scheme 3), which are potential biologically active compounds, were synthesized for the first time. Copyright
- Korkusuz, Elif,Yildirim, Ismail
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- Preparations of Copper(I) Complexes Ligated with Novel Hindered Pyrazolylborates
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Novel hindered pyrazolylborates, HB(3,5-Ph2pz)3- and HB(3,5-iPr2pz)3- were synthesized.Several copper(I) complexes ligated with these ligands were prepared and their properties are compared with the corresponding complexes with conventional pyrazolylborate as ligand.
- Kitajima, Nobumasa,Fujisawa, Kiyoshi,Fujimoto, Chisato,Moro-Oka, Yoshihiko
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- A facile and convenient approach to the synthesis of 3,5-diaryl-1H- pyrazoles
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A simple and convenient one-pot synthesis route is described for the synthesis of 3,5-diaryl-1H-pyrazoles in short reaction times from the reaction of α-epoxyketones with semicarbazide hydrochloride under mild conditions.
- Nikpour, Farzad,Beigvand, Mahdi
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- Additions of 5-phenyltetrazole and other heterocyclic NH compounds to olefins
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The reactivity of a range of heterocyclic NH compounds toward cyclohexene under p-toluenesulfonic acid catalysis was surveyed. 1,2,4-Triazole (38%), carbazole (67%) and 5-phenyltetrazole (83%) gave significant amounts of addition products. 5-Phenyltetrazole reacts with a wide range of unactivated olefins, to give addition products in 65% to 90% yield. This method represents a general, preparatively useful route to 2-alkyl-5-phenyltetrazoles. 1997 Plenum Publishing Corporation.
- Katritzky, Alan R.,Qi, Ming,Wells, Adam P.
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- Monoamine oxidase isoform-dependent tautomeric influence in the recognition of 3,5-diaryl pyrazole inhibitors
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A series of 3,5-diaryl pyrazoles were prepared and assayed for their ability to inhibit reversibly monoamine oxidase-A (MAO-A) and monoamine oxidase B (MAO-B). Several compounds show inhibitory activity with concentration values in the nanomolar range. A computational work was carried out on the two most selective inhibitors that have tautomeric pyrazole forms. The binding free energies of these compounds for each MAO isoform were influenced by the tautomeric equilibria.
- Chimenti, Franco,Fioravanti, Rossella,Bolasco, Adriana,Manna, Fedele,Chimenti, Paola,Secci, Daniela,Befani, Olivia,Turini, Paola,Ortuso, Francesco,Alcaro, Stefano
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- Metal-free cascade synthesis of unsymmetrical 2-aminopyrimidines from imidazolate enaminones
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A convenient metal-free synthesis of unsymmetrical 2-aminopyrimidines from imidazolate enaminones has been developed. In this procedure, various structural 2-aminopyrimidines, as well as 4,5-dihydroisoxazol-5-ols and pyrazoles were synthesized in moderate to excellent yields. A plausible mechanism was also proposed for the cascade reaction. This method represents an effective strategy towards the synthesis of unsymmetrical 2-aminopyrimidines.
- Cui, Xue,Li, Youbin,Ma, Jianting,Wang, Xuesong,Xu, Junyu,Zeng, Tingting
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- Propargyl Hydrazides as Useful Intermediates Leading to Pyrazoles via Reaction with Certain Electrophiles
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The reactions of propargyl hydrazides with certain electrophiles successfully led to the regioselective formation of various alkylated hydrazides. Reactions with electrophiles directly afforded the alkylated, chlorinated, brominated, and iodinated pyrazol
- Kiyokawa, Kosuke,Ito, Yukiteru,Kakehi, Ryoma,Ogawa, Takahiro,Goto, Yusuke,Yoshimatsu, Mitsuhiro
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- New "green" approaches to the synthesis of pyrazole derivatives
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A novel approach to the synthesis of pyrazole derivatives from tosylhydrazones of α,β-unsaturated carbonyl compounds possessing a β-hydrogen is proposed, exploiting microwave (MW) activation coupled with solvent free reaction conditions. The cycloaddition was studied on three ketones (trans-4-phenyl-3-buten-2-one, β-ionone and trans-chalcone). The corresponding 3,5-disubstitued-1H-pyrazoles were obtained in high yields and after short reaction times. In order to simplify and point out the green chemistry features of the method, a further improvement was achieved under the same catalytic conditions with a "one pot" synthesis of these heterocyclic compounds, starting directly from their carbonyl precursors via tosylhydrazones generated in situ. For an exhaustive study, the dielectric properties of the solid reaction mixtures were also measured, in order to obtain input data for the numerical simulation of their heating behaviour in the single mode MW cavity which was used for experimental work. In order to supply a valid methodology and tool for measuring the environmental impact, a comparative study between the synthetic route proposed and the classical synthetic route has been carried out.
- Corradi, Anna,Leonelli, Cristina,Rizzuti, Antonino,Rosa, Roberto,Veronesi, Paolo,Grandi, Romano,Baldassari, Sara,Villa, Carla
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- New one step synthesis of 3,5-disubstituted pyrazoles under microwave irradiation and classical heating
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(Chemical Equation Presented) A convenient one pot procedure for the synthesis of 3,5-disubstituted pyrazoles by condensation of chalcones, hydrazine hydrate and sulfur in ethanol under microwave irradiation and conventional heating method is reported. The hydrogen sulfide is produced during the reaction. The pyrazoles are obtained in good yields and excellent state of purity. The structures of new compounds were confirmed by IR, 1H, and 13C NMR, MS and elemental analysis.
- Outirite, Moha,Lebrini, Mounim,Lagrenee, Michel,Bentiss, Fouad
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- Synthesis of zirconia doped molybdenum oxide as efficient catalysts for ultrasound assisted synthesis of substituted pyrazoles
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To explore green methodology for the synthesis of mixed oxide, its catalytic activity and temperature stability of series of ZrO2/MoO3 and ZrO2 were prepared by sol-gel method and characterized by XRD, FT-IR, X-ray photoelectron spectroscopy (XPS), temperature programmed Desorption (TPD), Raman spectroscopy and transmission electron microscopes (TEM). These mixed oxides were showed high stability with nanocrystalline nature. Due to highly acidic nature of the catalysts, ultra sound assisted synthesis of substituted pyrazoles was carried out successfully with high yield. The reaction was carried out in solvent free medium, which showed green approach and energy saving reaction. Condensation of dibenzoyl methane and hydrazine to form substituted pyrazoles with 97.7% yield. The acid strength and acid amount of synthesized catalysts were determined by temperature programmed desoprtion (TPD), incorporation of zirconia into the molybdenum, network has changed its surface acid properties due to the Zr2+ and Mo6+ ions. After addition of ZrO2 on MoO3, it showed weak and strong acid sites.
- MUFTAH, AMAL A.,WAGHMODE, SHOBHA A.,GADALE, SHARDA R.
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p. 2007 - 2014
(2021/08/24)
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- Heteroaromatic Inhibitors of the Astacin Proteinases Meprin α, Meprin β and Ovastacin Discovered by a Scaffold-Hopping Approach
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Astacin metalloproteinases, in particular meprins α and β, as well as ovastacin, are emerging drug targets. Drug-discovery efforts have led to the development of the first potent and selective inhibitors in the last few years. However, the most recent compounds are based on a highly flexible tertiary amine scaffold that could cause metabolic liabilities or decreased potency due to the entropic penalty upon binding to the target. Thus, the aim of this study was to discover novel conformationally constrained scaffolds as starting points for further inhibitor optimization. Shifting from flexible tertiary amines to rigid heteroaromatic cores resulted in a boost in inhibitory activity. Moreover, some compounds already exhibited higher activity against individual astacin proteinases compared to recently reported inhibitors and also a favorable off-target selectivity profile, thus qualifying them as very suitable chemical probes for target validation.
- Tan, Kathrin,J?ger, Christian,K?rschgen, Hagen,Geissler, Stefanie,Schlenzig, Dagmar,Buchholz, Mirko,St?cker, Walter,Ramsbeck, Daniel
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supporting information
p. 976 - 988
(2020/12/25)
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- Discovery of pyrazole N-aryl sulfonate: A novel and highly potent cyclooxygenase-2 (COX-2) selective inhibitors
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Based on a new pyrazole sulfonate synthetic method, a novel class of molecules with a basic structure of pyrazole N-aryl sulfonate have been designed and synthesized. The interest in conducting intensive research stems from quite evident anti-inflammatory effects exhibited by the compounds in preliminary animal experiments. A series of compounds were synthesized by different substitutions of the R1, R2, and R3 groups. Within the series, 4-iodophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and phenyl 5-methyl-3-(4-(trifluoromethyl) phenyl)-1H-pyrazole-1-sulfonate exhibited excellent anti-inflammatory activity (% inhibition of auricular edemas = 27.0 and 35.9, respectively); the in vivo analgesic activity of phenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and 2-chlorophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate was confirmed to be effective (inhibition ratio of writhing = 50.7% and 48.5% separately), and compounds phenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate, 4-iodophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and 2-chlorophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate were identified as selective COX-2 inhibitors (SI = 455, 10,497 and >189 severally). In Acute Oral Toxicity assays conducted in vivo, the lethal dose 50 (LD50) of 4-iodophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate and 2-chlorophenyl 5-methyl-3-(p-tolyl)-1H-pyrazole-1-sulfonate to mice was >2000 mg/kg BW.
- Guo, Quanping,Wang, Mengran,Wang, Rui,Xu, Zhaoqing,Yao, Haiyan
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- Predicting the catalytic activity of azolium-based halogen bond donors: an experimentally-verified theoretical study
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This report demonstrates the successful application of electrostatic surface potential distribution analysis for evaluating the relative catalytic activity of a series of azolium-based halogen bond donors. A strong correlation (R2> 0.97) was observed between the positive electrostatic potential of the σ-hole on the halogen atom and the Gibbs free energy of activation of the model reactions (i.e., halogen abstraction and carbonyl activation). The predictive ability of the applied approach was confirmed experimentally. It was also determined that the catalytic activity of azolium-based halogen bond donors was generally governed by the structure of the azolium cycle, whereas the substituents on the heterocycle had a limited impact on the activity. Ultimately, this study highlighted four of the most promising azolium halogen bond donors, which are expected to exhibit high catalytic activity.
- Bolotin, Dmitrii S.,Il'in, Mikhail V.,Novikov, Alexander S.,Suslonov, Vitalii V.,Sysoeva, Alexandra A.
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p. 7611 - 7620
(2021/09/22)
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- One-Pot Palladium-Catalyzed Carbonylative Sonogashira Coupling using Carbon Dioxide as Carbonyl Source
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Carbonylation coupling reaction has emerged as a powerful and versatile strategy for the construction of carbonyl-containing compounds in modern synthetic chemistry over the past years. Carbon dioxide, a renewable one carbon molecule, has become one of the most attractive and promising alternative carbonyl sources due to its highly abundance, nontoxicity and stability in comparison with CO in recent years. However, in most cases, a two-chamber technique was generally necessary to allow the CO-producing and CO-consuming processes to perform successfully because of the complexities and incompatibility of reaction conditions, when carbon dioxide was utilized as carbonyl source. Herein, a practical one-pot protocol using carbon dioxide as the carbonyl source for the palladium-catalyzed carbonylative Sonogashira coupling has been established, providing an expedient and practical route to a wide range of functionalized alkynones and indoxyls under mild reaction conditions. By finding a suitable catalytic system, the method allowed the CO-generating and CO-consuming processes to proceed in one pot, wherein carbon monoxide was generated in situ from the reduction of carbon dioxide in the absence of any fluoride reagents. Simple and safe operation, readily available substrates, good functional group tolerance and mild reaction conditions are the features of the method.
- Xiong, Wenfang,Wu, Bowen,Zhu, Baiyao,Tan, Xiaobin,Wang, Lu,Wu, Wanqing,Qi, Chaorong,Jiang, Huanfeng
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p. 2843 - 2851
(2021/05/10)
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- Green, homogeneous oxidation of alcohols by dimeric copper(II) complexes
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Three pyrazole derivatives, 3,5-dimethyl-1H-pyrazole (DMPz) (I), 3-methyl-5-phenyl-1H-pyrazole (MPPz) (II), and 3,5-diphenyl-1H-pyrazole (DPPz) (III), were prepared via reacting semicarbazide hydrochloride with the acetylacetone, 1-phenylbutane-1,3-dione, and 1,3-diphenylpropane-1,3-dione, respectively. Complexes 1–3 were isolated by reacting CuCl2·2H2O with I–III, respectively, and characterized by CHNS elemental analyses, FT-IR, UV-Vis, 1H and 13C NMR, EPR spectra, and TGA/DTA. Molecular structures of the pyrazole derivatives I–III and copper(II) complexes 2 and 3 were studied through single-crystal XRD analysis to confirm their molecular structures. Overlapping of hyperfine splitting in the EPR spectra of the dimeric copper(II) complexes 1–3 indicates that both copper centers do not possess the same electronic environment in solution. The copper(II) complexes are dimeric in solid state as well as in solution and catalyze the oxidation of various primary and secondary alcohols selectively. Catalysts 1–3 show more than 92% product selectivity toward ketones during the oxidation of secondary alcohols. Surprisingly primary alcohols, which are relatively difficult to oxidize, produce carboxylic acid as a major product (48%–90% selectivity) irrespective of catalytic systems. The selectivity for carboxylic acid rises with decreasing the carbon chain length of the alcohols. An eco-friendly and affordable catalytic system for oxidation of alcohols is developed by the utilization of H2O2, a green oxidant, and water, a clean and greener solvent, which is a notable aspect of the study.
- Maurya, Abhishek,Haldar, Chanchal
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p. 885 - 904
(2020/12/18)
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- Base promoted CuFe2O4 catalyzed one-pot synthesis of 3,5-diaryl-1H-pyrazoles
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Available synthetic protocols for 3,5-diaryl-1H-pyrazoles generally demand long reaction time. Herein, we are reporting a CuFe2O4 catalyzed synthetic procedure for the same that delivers products in significantly reduced time starting from tosylhydrazones of aromatic aldehydes and terminal alkynes. Under the reaction condition, tosylhydrazone generates diazo compound in situ, which then undergoes [3 + 2] cycloaddition reaction with the terminal alkyne followed by [1,3]-H shift to deliver the final products in 72%–85% isolated yield. Magnetically active CuFe2O4 nanoparticles can be recovered very easily after the completion of the reaction and can be reused up to fifth cycle without significant loss in its catalytic activity. Operational simplicity of the methodology along with tolerability of various functional groups as well as easy recovery and high reusability of CuFe2O4 nanoparticles make the procedure a practical and handy one for the synthesis of 3,5-diaryl-1H-pyrazoles.
- Bhuyan, Pubanita,Saikia, Lakhinath
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supporting information
(2021/11/16)
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- Chalcone-inspired rA1/A2A adenosine receptor ligands: Ring closure as an alternative to a reactive substructure
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Over the past few years, great progress has been made in the development of high-affinity adenosine A1 and/or A2A receptor antagonists—promising agents for the potential treatment of Parkinson's disease. Unfortunately, many of these compounds raise structure-related concerns. The present study investigated the effect of ring closures on the rA1/A2A affinity of compounds containing a highly reactive α,β-unsaturated carbonyl system, hence providing insight into the potential of heterocycles to address these concerns. A total of 12 heterocyclic compounds were synthesised and evaluated in silico and in vitro. The test compounds performed well upon qualitative assessment of drug-likeness and were generally found to be free from potentially problematic fragments. Most also showed low/weak cytotoxicity. Results from radioligand binding experiments confirm that heterocycles (particularly 2-substituted 3-cyanopyridines) can replace the promiscuous α,β-unsaturated ketone functional group without compromising A1/A2A affinity. Structure–activity relationships highlighted the importance of hydrogen bonds in binding to the receptors of interest. Compounds 3c (rA1Ki?=?16?nM; rA2AKi?=?65?nM) and 8a (rA1Ki?=?102?nM; rA2AKi?=?37?nM), which both act as A1 antagonists, showed significant dual A1/A2A affinity and may, therefore, inspire further investigation into heterocycles as potentially safe and potent adenosine receptor antagonists.
- Aucamp, Janine,Janse van Rensburg, Helena D.,Legoabe, Lesetja J.,Matthee, Chrisna,Terre’Blanche, Gisella
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- Nano-SnCl4 /SiO2 as a catalyst for one-pot synthesis of substituted 1h-pyrazoles as antifungal and cytotoxic agents
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A simple and efficient method was developed for the synthesis of pyrazole derivatives via a one-pot reaction of 1,3-diketone and substituted hydrazines in the presence of nano-SnCl4/SiO2 as a mild catalyst. A series of some pyrazole derivatives (P1-P11) was synthesized and evaluated as anti-fungal and anti-cancer agents. Compounds P10 and P11 were demonstrated. The antimicrobial activities of the synthetic compounds showed that compounds P10 and P11 most excellently inhibited the growth of dermatophytes or Aspergillus species, respectively. Therefore, the cytotoxic activities of the-se compounds on two human cancer cell lines, A549 (lung cancer) and MCF-7 (breast cancer) were further assessed. Hence, results demonstrated that beside antifungal activity, P10 had also desirable cy-totoxic effect on investigated cancerous cell lines, even higher than cisplatin.
- Faghih, Zeinab,Khabnadideh, Soghra,Mirjalili, Bi Bi Fatemeh,Moradi, Hadi,Zamani, Leila,Zomorodian, Kamiar
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p. 459 - 465
(2020/04/21)
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- Pyrazole derivative compound, and preparation method and application thereof
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The invention belongs to the technical field of medicine synthesis, and particularly relates to a pyrazole derivative compound, and a preparation method and an application thereof. The polysubstitutedpyrazole compound disclosed by the invention has a structure represented by a formula (I), wherein R1, R2 and R3 in the formula are respectively defined in the specification. The invention also relates to an agricultural composition containing the compound or the pharmaceutically acceptable salt thereof. The prepared compound has good safener activity, can well relieve the toxicity of herbicidesto crops after being used, and is beneficial to the growth of crops. Compared with similar compounds, the compound provided by the invention shows good detoxification effect and safety.
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Paragraph 0039-0040; 0059-0060
(2020/04/06)
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- Denitrative imino-diaza-Nazarov cyclization: Synthesis of pyrazoles
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An iodine-catalyzed denitrative imino-diaza-Nazarov cyclization (DIDAN) methodology has been developed for the synthesis of pyrazoles with high to excellent yields by using α-nitroacetophenone derivatives and in situ generated hydrazones. The key transformation of this oxidative 4π-electrocyclization proceeds through an enamine-iminium ion intermediate. This rapid one-pot DIDAN protocol results in the selective generation of C-C and C-N bonds and cleavage of a C-N bond. This journal is
- Aegurla, Balakrishna,Jarwal, Nisha,Peddinti, Rama Krishna
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p. 6100 - 6107
(2020/10/21)
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- Selective Dehydrogenative Acylation of Enamides with Aldehydes Leading to Valuable β-Ketoenamides
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We have presented a unique example of dehydrogenative acylation of enamides with aldehydes enabled by an earth-abundant iron catalyst. The protocol provides the straightforward access to valuable β-ketoenamides with ample substrate scope and excellent functional group tolerance. Notably, distinct C-H acylation of enamide rather than at N-H moiety site occurs with absolute Z-selectivity was observed. Late-stage modifications of complex molecules and versatile synthetic utility of β-ketoenamides further highlight the practicability of this transformation.
- Liu, Rui-Hua,Shen, Zhen-Yao,Wang, Cong,Loh, Teck-Peng,Hu, Xu-Hong
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supporting information
p. 944 - 949
(2020/02/15)
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- Synthesis and theoretical study of a series of 3,5-disubstitutes pyrazoles
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In this work, we proposed the synthesis of a series of pyrazoles derivatives with different substituents on the aromatic rings. We aim to evaluate their influence on the reactivity of the compounds in reactions of α,β-unsaturated chalcones and sulfonyl hydrazide catalyzed by iodine. In order to explain their high and low yields, or the impossibility of obtaining some compounds by applied synthetic methodology, Density Functional Theory (DFT) calculations were performed. The reaction Gibbs free energy (ΔG) as well as the energy gap of the HOMO-LUMO frontier orbitals (ΔE) of some selected reactants could explain qualitatively the experimental observations in terms of synthesis yield. In this way, we believe that the chemical nature of aromatic ring substituents is relevant for the reactivity of the starting materials as well as the formation of the desired products.
- Branco, Ana Clara Alves,Couri, Mara Rubia Costa,Enes, Karine Braga,Guimar?es, Luciana,Lima, Maria Eduarda Toledo,Mateus, Marcella Fernandes Mano,Nascimento, Clebio Soares
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p. 932 - 938
(2020/12/23)
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- Trisulfur-Radical-Anion-Triggered C(sp2)-H Amination of Electron-Deficient Alkenes
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A trisulfur-radical-anion (S3˙-)-triggered C(sp2)-H amination of α,β-unsaturated carbonyl derivatives with simple amines has been demonstrated. This protocol provides convenient access to a variety of synthetically valuable N-unprotected and secondary β-enaminones with absolute Z selectivity and tertiary β-enaminones with E selectivity. Mechanistic probe and electronic structure theory calculations suggest that S3˙- initiates the nucleophilic attacks via a thiirane intermediate.
- Nguyen, Khang X.,Nguyen, Thao T.,Nguyen, Tung T.,Pham, Hoai T. B.,Pham, Phuc H.,Phan, Nam T. S.,Wang, Haobin,Yang, Chou-Hsun
-
supporting information
p. 9751 - 9756
(2020/12/21)
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- Copper-Promoted Oxidative Intramolecular C–H Amination of Hydrazones to Synthesize 1H-Indazoles and 1H-Pyrazoles Using a Cleavable Directing Group
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A facile and efficient synthesis of 1H-indazoles and 1H-pyrazoles through a copper-promoted oxidative intramolecular C–H amination of hydrazones using a cleavable directing group was developed. This reaction is characterized by its mild conditions, operational simplicity, readily available reagents, and excellent yields. A tentative mechanism for Cu-mediated C–H oxidative amination was proposed.
- Zhang, Guofu,Fan, Qiankun,Zhao, Yiyong,Ding, Chengrong
-
supporting information
p. 5801 - 5806
(2019/08/02)
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- The Direct Conversion of α-Hydroxyketones to Alkynes
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Alkynes are highly important functional groups in organic chemistry, both as part of target structures and as versatile synthetic intermediates. In this study, a protocol for the direct conversion of α-hydroxyketones to alkynes is reported. In combination with the variety of synthetic methods that generate the required starting materials by forming the central C-C bond, it enables a highly versatile fragment coupling approach toward alkynes. A broad scope for this novel transformation is shown alongside mechanistic insights. Furthermore, the utility of our protocol is demonstrated through its application in concert with varied α-hydroxyketone syntheses, giving access to a broad spectrum of alkynes.
- Ghiringhelli, Francesca,Nattmann, Lukas,Bognar, Sabine,Van Gemmeren, Manuel
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p. 983 - 993
(2019/01/24)
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- Fast and Efficient Continuous Flow Method for the Synthesis of Ynones and Pyrazoles
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In this study, we developed a convenient and efficient two-step method for the synthesis of ynones in a flow reactor, through the generation of lithium acetylide and its subsequent reactions with acid chlorides. Using this approach, we obtained the ynones in moderate to good yields at room temperature. Moreover, we transformed the ynones into pyrazole derivatives through coupling with hydrazines. This transition metal-free process, mild reaction conditions, and broad functional group tolerance are all attractive features in comparison with conventional bench-top methods.
- Kandasamy, Mohanraj,Ganesan, Balaji,Hung, Min-Yuan,Lin, Wei-Yu
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p. 3183 - 3189
(2019/05/28)
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- One-pot regioselective synthesis of substituted pyrazoles and isoxazoles in PEG-400/water medium by Cu-free nano-Pd catalyzed sequential acyl Sonogashira coupling-intramolecular cyclization
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Catalyst efficacy of in situ generated Pd-nanoparticles (PdNPs) in the regioselective one-pot synthesis of 3,5-di & 3,4,5-trisubstituted pyrazoles and 3,5-disubstituted isoxazoles in environmentally benign PEG-400/H2O medium, which involves the sequential (i) Cu-free acyl-Sonogashira coupling (ASC) and (ii) intramolecular ynone-amine cyclization under PTC conditions was described. The results of controlled experiments support the operation of two sequential catalytic cycles (ASC/cyclization) and achievement of complementary/opposite regioselectivity via ynone-bound palladium in a one-pot approach. Moreover, the in situ PdNPs recovered after the first catalytic cycle of the one-pot reaction sequence have been reused again five times successively. Besides, prior to the above studies, the efficacy of some common Pd-N-heterocyclic carbene (Pd-NHC) complexes in catalyzing the same one-pot two-step reaction sequence (Cu-free ASC/cyclization) both in water and organic solvents was also optimized. In situ generation of PdNPs from above Pd-NHCs in water was also identified, but they are not reusable due to their large size distribution.
- Thirukovela, Narasimha Swamy,Balaboina, Ramesh,Botla, Vinayak,Vadde, Ravinder,Jonnalagadda, Sreekantha Babu,Vasam, Chandra Sekhar
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p. 6471 - 6481
(2019/11/20)
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- 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)
- -
-
Paragraph 0111-0115
(2019/12/02)
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- An Efficient Synthesis of Substituted Pyrazoles from One-Pot Reaction of Ketones, Aldehydes, and Hydrazine Monohydrochloride
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An efficient, one-pot and metal-free process for the preparation of 3,5-disubstituted and 3,4,5-trisubstituted pyrazoles on multi-gram scale was developed. One-pot condensation of ketones, aldehydes and hydrazine monohydrochloride readily formed pyrazoline intermediates under mild conditions. Oxidation of pyrazolines, in situ, employing bromine afforded a wide variety of pyrazoles. The methodology offers a fast, and often chromatography-free protocol for the synthesis of 3,4,5-substituted pyrazoles in good to excellent yields. Alternatively, a more benign oxidation protocol affords 3,5-disubstituted or 3,4,5-trisubstituted pyrazoles by simply heating pyrazolines in DMSO under oxygen.
- Lellek, Vit,Chen, Cheng-Yi,Yang, Wanggui,Liu, Jie,Ji, Xuebao,Faessler, Roger
-
supporting information
p. 1071 - 1075
(2018/02/26)
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- Cu1.5PMo12O40-catalyzed condensation cyclization for the synthesis of substituted pyrazoles
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A convenient and direct approach has been developed for the preparation of pyrazole derivatives by the condensation cyclization of hydrazines/hydrazide and 1,3-diketones in the presence of Cu1.5PMo12O40 (0.33?mol%) under mild conditions (r.t.-60?°C, 10–30?min). Notably, the reaction was found to be scalable as 99% yield was obtained when the reaction was performed at a 5-mmol scale. This solvent-free and halogen-free catalytic system represents an effective economic and environmentally friendly method for the construction of pyrazoles.
- Yang, Guo-Ping,He, Xing,Yu, Bing,Hu, Chang-Wen
-
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- Pyrazole compound containing N-aryl sulfonate and synthesis and application thereof
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The invention discloses a pyrazole compound containing N-aryl sulfonate. A structural formula of the pyrazole compound is shown in the description. Proofed by pharmacological study, the pyrazole compound has the advantages that the activity of cyclooxygenase 2 is inhibited; the high-efficiency inhibition function on the generation of cyclooxygenase 2 due to inflammation mediums is realized, so that the pyrazole compound can be used as an active matter, and the prepared anti-inflammation medicine can be used for treating the inflammations, such as rheumatic arthritis and rheumatalgia, and the diseases and symptoms, such as fevers.
- -
-
Paragraph 0016
(2018/07/10)
-
- Biomimetic Cleavage of Aryl–Nitrogen Bonds in N-Arylazoles Catalyzed by Metalloporphyrins
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The cleavage of C–N single bonds of N-containing compounds provides either an excellent nitrogen source or an excellent carbon source. In this study, an efficient metalloporphyrins/H2O2 cleavage of C–N bonds of arylpyrazoles was investigated. The effects of different factors, including different catalysts, catalyst dosages, H2O2 dosages, reaction temperature and reaction time were studied. The experimental results showed that the optimal catalyst was FeTPPCl, and the yield of pyrazole derivatives could reach up to 12.3%, which was fourfold higher than hemin catalyzed reaction and closed to ceric ammonium nitrate catalyzed reaction, respectively. Compared with transition-metal-catalyzed and strong-oxidization cleavage of C–N bonds, this protocol is characterized by environmentally-friendly, stable, mild reaction conditions and simplified operation procedures. Graphical Abstract: [Figure not available: see fulltext.].
- Yu, Zongjiang,Zhai, Guoqing,Xian, Mo,Lu, Ming,Wang, Pengcheng,Jiang, Tao,Xu, Chao,Sun, Weizhi
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p. 2636 - 2642
(2018/06/20)
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- Metal-free and fecl3-catalyzed synthesis of azines and 3,5-diphenyl-1H-pyrazole from hydrazones and/or ketones monitored by high resolution ESI+-MS
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9-Fluorenone azine 2a or benzophenone azine 2b have been synthesized, respectively, by treatment of 9-fluorenone hydrazone la or benzophenone hydrazone lb with FeCl3 Lewis acid catalyst in CHCb. Treatment of la and lb with FeCb affords the asymmetrical azine l-(diphenylmethylene)-2-(9H-fluoren-9-ylidene)hydrazine 2c. l,3-Diphenyl-2-propenone 3 reacts with hydrazine to produce l-((E)-l,3-diphenylallylidene)hydrazine 3a. Under prolonged heating, 3a undergoes a cyclization to yield 3,5-diphenyl-lH-pyrazoIe 4. Chalcone 3 reacts with la or lb to produce a mixture of 4 and 2a or 4 and 2b, respectively. The reaction of cyclohexanone 5 with hydrazine leads to the formation of 1,2-dicyclohexylidene hydrazine 6. Ketone 5 reacts with la or lb to give the asymmetrical azine product 6a or 6b, respectively. The progress of the reactions has been monitored by electrospray ionization mass spectrometry (ESI-MS), and the compounds have been characterized by elemental analyses, IR,1H,13C and DEPT-135 NMR spectroscopy and also by high resolution ESI+-MS.
- Lasri, Jamal,Ismail, Ali I.
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p. 362 - 373
(2019/05/21)
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- Regio- and Stereoselective Hydrosulfonylation of Electron-Deficient Alkynes: Access to Both E- and Z-β-Sulfonyl-α,β-Unsaturated Carbonyl Compounds
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A metal-free hydrosulfonylation of electron-deficient alkynes with sodium sulfinates or sulfinic acids to access both E- and Z-β-sulfonyl-α,β-unsaturated carbonyl compounds has been developed. We propose that this reaction via a hydroxylallene intermediate delivers the thermodynamically stable E isomer, or via a concerted termolecular AdE3 mechanism affords Z isomer. The stereoselectivity of addition (syn or anti) can be controlled by varying the sulfonyl sources and acidic buffer solutions. This protocol exhibits broad substrate scope for internal or terminal alkynes including various substituted ynones and alkynyl esters. This approach is mild, efficient, operationally simple and easy to be scaled-up. (Figure presented.).
- Zhang, Wei,Johnson, Gabriel M.,Guan, Zhi,He, Yan-Hong
-
supporting information
p. 4562 - 4570
(2018/10/24)
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- Method for breaking C-N bond through biomimetic catalysis in aryl nitrogen-containing compound
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The invention discloses a method for breaking a C-N bond through biomimetic catalysis in an aryl nitrogen-containing compound. A reaction system for breaking the C-N bond in the aryl nitrogen-containing compound through metalloporphyrin mimic enzyme biomimetic catalysis is used, and the preparation of the catalyst and the optimization of the reaction system are involved. Iron porphyrin, manganeseporphyrin and cobalt porphyrin are adopted as mimetic enzymes and H2O2 is used as an oxidant to respectively break the C-N bonds of arylpyrazole derivatives with different structures through catalyst,the yield of a nitrogen heterocyclic product can reach 15.2% to the largest content, and the yield is 4 times of that of bio-enzyme catalysis, and is close to the yield (20%) of cerium ammonium nitrate oxidation. The method has the advantages of simplicity, mildness, economy, and greenness compared with conventional oxidants or transition metal catalyst systems.
- -
-
Paragraph 0025; 0026
(2018/09/21)
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- Sunlight-promoted Direct Irradiation of N-centred Anion: The Photocatalyst-free Synthesis of Pyrazoles in Water
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A practical method through sunlight mediated annulation of α,β-unsaturated hydrazones has been developed for the synthesis of pyrazole. Based on the analysis of UV-Vis absorption of the substrate, the reaction was designed to avoid the use of external photocatalysis and proceeds via direct irradiation of N-centred anion by sunlight. The key features of this reaction include operational simplicity, readily available reagents, and amenability to gram-scale synthesis. (Figure presented.).
- Zhang, Te,Meng, Yunge,Lu, Jinye,Yang, Yuting,Li, Gong-Qiang,Zhu, Chunyin
-
supporting information
p. 3063 - 3068
(2017/12/04)
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- Versatile Tri(pyrazolyl)phosphanes as Phosphorus Precursors for the Synthesis of Highly Emitting InP/ZnS Quantum Dots
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Tri(pyrazolyl)phosphanes (5R1,R2) are utilized as an alternative, cheap and low-toxic phosphorus source for the convenient synthesis of InP/ZnS quantum dots (QDs). From these precursors, remarkably long-term stable stock solutions (>6 months) of P(OLA)3 (OLAH=oleylamine) are generated from which the respective pyrazoles are conveniently recovered. P(OLA)3 acts simultaneously as phosphorus source and reducing agent in the synthesis of highly emitting InP/ZnS core/shell QDs. These QDs are characterized by a spectral range between 530–620 nm and photoluminescence quantum yields (PL QYs) between 51–62 %. A proof-of-concept white light-emitting diode (LED) applying the InP/ZnS QDs as a color-conversion layer was built to demonstrate their applicability and processibility.
- Panzer, René,Guhrenz, Chris,Haubold, Danny,Hübner, René,Gaponik, Nikolai,Eychmüller, Alexander,Weigand, Jan J.
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supporting information
p. 14737 - 14742
(2017/10/23)
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- Metal-Free Synthesis of Pyrazoles from 1,3-Diarylpropenes and Hydrazines via Multiple Inter-/Intramolecular C–H Aminations
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A facile and metal-free access to pyrazoles from 1,3-diarylpropenes and hydrazines via multiple inter-/intramolecular C-H aminations was described. Under the neutral and mild 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) oxidative conditions, various disubstituted pyrazoles were synthesized in moderate to excellent yields. This method provides a pot- and step-economic strategy for the construction of pyrazoles, especially those for drug discovery. (Figure presented.).
- Tang, Li,Ma, Minyan,Zhang, Qi,Luo, Huan,Wang, Tao,Chai, Yonghai
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p. 2610 - 2620
(2017/08/16)
-
- 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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- Copper-Mediated Domino Cyclization/Trifluoromethylation/Deprotection with TMSCF3: Synthesis of 4-(Trifluoromethyl)pyrazoles
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A copper-mediated synthesis of 4-(trifluoromethyl)pyrazoles is described. In one step from readily accessible α,β-alkynic tosylhydrazones, a remarkable domino sequence of cyclization, trifluoromethylation, and detosylation takes place to furnish the 4-CF3 N-H pyrazole cores with good functional group compatibility. The reaction conditions are mild and convenient, at room temperature in air, using the commercially available trifluoromethyltrimethylsilane (TMSCF3) as the CF3 source. The method can be applied to the synthesis of a 4-CF3 analogue of the anti-inflammatory drug celecoxib.
- Wang, Quande,He, Lisi,Li, Kin Keung,Tsui, Gavin Chit
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p. 658 - 661
(2017/02/10)
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- Nano-TiO2: An efficient and reusable catalyst for the synthesis of 1,3,5-substituted pyrazoles
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(Formula presented) A Nano-TiO2 is an efficient catalysis for the synthesis of 1,3,5-substituted pyrazoles via condensation of 1,3- diketones and hydrazines. Simple procedure, mild heating, solvent free, high yielding, and easy workup are some advantages of this protocol. The catalyst can be recovered easily and reused many times without significant loss in catalytic activity and selectivity.
- Akbari, Ali,Mirjalili, Bibi Fatemeh
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p. 119 - 123
(2016/07/15)
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- Synthesis, crystal structure and photophysical study of luminescent three-coordinate cuprous bromide complexes based on pyrazole derivatives
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The 1: 2 M-ratio reaction between cuprous bromide and pyrazole derivatives in toluene results in mononuclear Cu(I) complexes [CuBr(pyrazole)2]. The complexes have been characterized by 1H NMR spectroscopy and elemental analysis. The molecular structure, established by single-crystal X-ray diffraction, features a trigonal planar geometry around copper, with monodentate pyrazole derivatives. All the Cu(I) complexes are luminescent in the solid state at ambient temperature. Intense blue or blue-green emission in the solid state is observed for these complexes, with the maxima ranging from 431 to 493 nm. The observed photoluminescence could be ascribed to the metal-to-ligand charge-transfer excited states, probably mixed with some halide-to-ligand character. The microsecond lifetime scale of the complexes implies that these transitions arise from the triplet excited states.
- Wu, Fengshou,Tong, Hongbo,Wang, Kai,Zhang, Xiulan,Zhang, Jie,Wong, Wai-Kwok,Zhu, Xunjin
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p. 926 - 933
(2016/04/08)
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- Iron(III) phthalocyanine chloride-catalyzed oxidation-aromatization of α,β-unsaturated ketones with hydrazine hydrate: Synthesis of 3,5-disubstituted 1H-pyrazoles
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We have developed an iron(III) phthalocyanine chloride-catalyzed oxidation-aromatization of α,β-unsaturated ketones with hydrazine hydrate. Various 3,5-disubstituted 1H-pyrazoles were obtained in good to excellent yields. This method offers several advantages, including room-temperature conditions, short reaction time, high yields, simple work-up procedure, and use of air as an oxidant. The catalyst can be recovered and reused five times without loss of activity.
- Zhao, Junlong,Qiu, Jun,Gou, Xiaofeng,Hua, Chengwen,Chen, Bang
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p. 571 - 578
(2016/04/20)
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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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- A highly efficient heterogeneous palladium-catalyzed cascade three-component reaction of acid chlorides, terminal alkynes and hydrazines leading to pyrazoles
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In the presence of 0.5 mol% of 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized palladium(II) complex [MCM-41-2N-Pd(OAc)2] and 1.0 mol% of CuI, acid chlorides were coupled with terminal alkynes in Et3N at 50 °C to give α,β-unsaturated ynones, which were converted in situ into pyrazoles by the cycloaddition of hydrazines at room temperature with acetonitrile as cosolvent. The cascade reactions generated a variety of pyrazole derivatives in moderate to good yields, and this heterogeneous palladium catalyst exhibited higher catalytic activity than PdCl2(PPh3)2 and could be recovered and reused for at least 10 consecutive trials without any decreases in activity.
- Chen, Qiurong,Yao, Fang,Yin, Lin,Cai, Mingzhong
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p. 108 - 113
(2016/01/15)
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- A facile and expeditious approach to substituted 1H-pyrazoles catalyzed by iodine
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A facile and expeditious method for the synthesis of 1H-pyrazoles by the reaction of α,β-unsaturated aldehydes/ketones and sulfonyl hydrazide catalyzed by as low as 2 mol % I2 has been demonstrated. This synthetic system features simple operation and mild reaction conditions, and displays a broad functional group tolerance furnishing good to excellent yields.
- Zhang, Hailei,Wei, Qian,Zhu, Guodong,Qu, Jingping,Wang, Baomin
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p. 2633 - 2637
(2016/06/01)
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- PRODUCING METHOD OF NITROGEN-CONTAINING ORGANIC COMPOUND
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A hydrazine-carbon dioxide-binding compound or hydrazine derivatives 2 carbonyl group react with a compound having one or more nitrogen-containing organic for preparing the compounds of relates to method.
- -
-
Paragraph 0290-0292
(2016/12/01)
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- A modified and practical synthetic route to indazoles and pyrazoles using tungstate sulfuric acid
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Tungstate sulfuric acid-catalyzed Knorr reaction have been used as a simple, rapid, atom economic and green method for the synthesis of indazole and pyrazole derivatives based on the condensation of hydrazine derivatives and ss-dicarbonyl compounds under solvent-free conditions. It was found that the catalyst could be recovered and reused without significant loss of its activity. The use of this method provides a novel and improved modification of Knorr synthesis in terms of clean reaction profile, use of a safe catalyst and solvent-free conditions. A green method for the synthesis of indazole and pyrazole derivatives from the condensation of hydrazine derivatives with dicarbonyl compounds has been described. Tungstate sulfuric acid (TSA) catalyzed efficiently the reactions to give good yields.
- Rahmatzadeh, S. Setareh,Karami, Bahador,Khodabakhshi, Saeed
-
-
- Copper-catalyzed aerobic cascade cycloamination and acyloxylation: A direct approach to 4-acyloxy-1H-pyrazoles
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A novel direct transformation of hydrazones to acyloxylated pyrazoles by copper-catalyzed regioselective olefinic C(sp2)-H bond cycloamination and acyloxylation was performed under mild conditions, which combines the formation of the pyrazole skeleton and installation of an acyloxyl group in a single step, using facile carboxylic acids as the acyloxylation reagents.
- Ding, Zhengwei,Tan, Qitao,Gao, Mingchun,Xu, Bin
-
supporting information
p. 4642 - 4646
(2015/04/27)
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- Sulphur promoted C(sp3)-C(sp2) cross dehydrogenative cyclisation of acetophenone hydrazones with aldehydes: Efficient synthesis of 3,4,5-trisubstituted 1H-pyrazoles
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A novel strategy for the cross dehydrogenative coupling (CDC) of acetophenone hydrazones and aldehydes has been developed for the synthesis of highly substituted pyrazoles. This work, for the first time, uses elemental sulfur as a promoter as well as a hydrogen acceptor in effecting the Csp3-Csp2 bond formation via C-H activation. This journal is
- Vanjari, Rajeshwer,Guntreddi, Tirumaleswararao,Kumar, Saurabh,Singh, Krishna Nand
-
supporting information
p. 366 - 369
(2015/01/09)
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- Synthesis of 3,5-disubstituted-1H-pyrazoles from acid chlorides, alkynes, and hydrazine in the presence of silica-supported-zinc bromide
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An efficient one-pot palladium- And copper-free procedure has been developed for a convenient synthesis of 3,5-disubstituted-1H-pyrazoles from various acid chlorides, terminal alkynes and hydrazine by a coupling reaction and cyclocondensation sequence. Acid chlorides react with terminal alkynes in the presence of silica-supported-zinc bromide to give α,β-unsaturated ynones, and in situ conversion into pyrazoles by the hydrazine cyclocondensation.
- Keivanloo, Ali,Bakherad, Mohammad,Samangooei, Shahrzad
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p. 484 - 486
(2015/11/03)
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- Synthesis of Chiral Pyrazoles: A 1,3-Dipolar Cycloaddition/[1,5] Sigmatropic Rearrangement with Stereoretentive Migration of a Stereogenic Group
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The reactions between terminal alkynes and α-chiral tosylhydrazones lead to the obtention of chiral pyrazoles with a stereogenic group directly attached at a nitrogen atom. The cascade reaction includes decomposition of the hydrazone into a diazocompound, 1,3-dipolar cycloaddition of the diazo compound with the alkyne, and [1,5] sigmatropic rearrangement with migration of the stereogenic group. This strategy has been successfully applied to the synthesis of structurally diverse chiral pyrazoles through α-chiral tosylhydrazones, obtained from α-phenylpropionic acid, α-amino acids, and 2-methoxycyclohexanone. Notably, the stereoretention of the [1,5] sigmatropic rearrangements represent very rare examples of this stereospecific transformation.
- Pérez-Aguilar, M. Carmen,Valdés, Carlos
-
supporting information
p. 13729 - 13733
(2015/11/11)
-
- Reactivity of an iron-oxygen oxidant generated upon oxidative decarboxylation of biomimetic iron(II) α-hydroxy acid complexes
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Three biomimetic iron(II) α-hydroxy acid complexes, [(Tp Ph2)FeII(mandelate)(H2O)] (1), [(Tp Ph2)FeII(benzilate)] (2), and [(TpPh2)Fe II(HMP)] (3), together with two iron(II) α-methoxy acid complexes, [(TpPh2)FeII(MPA)] (4) and [(Tp Ph2)FeII(MMP)] (5) (where HMP = 2-hydroxy-2- methylpropanoate, MPA = 2-methoxy-2-phenylacetate, and MMP = 2-methoxy-2-methylpropanoate), of a facial tridentate ligand TpPh2 [where TpPh2 = hydrotris(3,5-diphenylpyrazole-1-yl)borate] were isolated and characterized to study the mechanism of dioxygen activation at the iron(II) centers. Single-crystal X-ray structural analyses of 1, 2, and 5 were performed to assess the binding mode of an α-hydroxy/methoxy acid anion to the iron(II) center. While the iron(II) α-methoxy acid complexes are unreactive toward dioxygen, the iron(II) α-hydroxy acid complexes undergo oxidative decarboxylation, implying the importance of the hydroxyl group in the activation of dioxygen. In the reaction with dioxygen, the iron(II) α-hydroxy acid complexes form iron(III) phenolate complexes of a modified ligand (TpPh2*), where the ortho position of one of the phenyl rings of TpPh2 gets hydroxylated. The iron(II) mandelate complex (1), upon decarboxylation of mandelate, affords a mixture of benzaldehyde (67%), benzoic acid (20%), and benzyl alcohol (10%). On the other hand, complexes 2 and 3 react with dioxygen to form benzophenone and acetone, respectively. The intramolecular ligand hydroxylation gets inhibited in the presence of external intercepting agents. Reactions of 1 and 2 with dioxygen in the presence of an excess amount of alkenes result in the formation of the corresponding cis-diols in good yield. The incorporation of both oxygen atoms of dioxygen into the diol products is confirmed by 18O-labeling studies. On the basis of reactivity and mechanistic studies, the generation of a nucleophilic iron-oxygen intermediate upon decarboxylation of the coordinated α-hydroxy acids is proposed as the active oxidant. The novel iron-oxygen intermediate oxidizes various substrates like sulfide, fluorene, toluene, ethylbenzene, and benzaldehyde. The oxidant oxidizes benzaldehyde to benzoic acid and also participates in the Cannizzaro reaction.
- Paria, Sayantan,Chatterjee, Sayanti,Paine, Tapan Kanti
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supporting information
p. 2810 - 2821
(2014/04/03)
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- Design and synthesis of 3-trifluoromethyl-3h-pyrazoles and further investigations of their transformation to 1h-pyrazoles
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An efficient intramolecular cycloaddition strategy for the synthesis of trifluoromethyl-substituted 3H-pyrazoles was developed. Subsequently, their wide applications were demonstrated: they (1) react with dioxane by a radical process and (2) undergo [1,5] sigmatropic rearrangements. These applications are useful as the products were obtained in high yields and with excellent regioselectivity.
- Sha, Qiang,Liu, Haixuan,Wei, Yunyang
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p. 7707 - 7715
(2015/04/22)
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- One-pot oxidation and rearrangement of propargylamines and in situ pyrazole synthesis
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Reported here are procedures for a one-pot oxidation and rearrangement of propargylamines to synthesize enaminones, with supporting mechanistic studies. Also reported are the extended one-pot syntheses of pyrazoles, including celecoxib and various heterocyclic compounds.
- Chen, Jinshan,Properzi, Roberta,Uccello, Daniel P.,Young, Jennifer A.,Dushin, Russell G.,Starr, Jeremy T.
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p. 4146 - 4149
(2014/09/29)
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