- Oxone?-promoted one-pot synthesis of 1-aryl-4-(organylselanyl)-1H-pyrazoles
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We describe herein an efficient protocol for the one-pot synthesis of 4-organylselanylpyrazoles by direct cyclocondensation and C-H bond selenylation reactions starting from hydrazines, 1,3-diketones and diorganyl diselenides promoted by Oxone?
- Jacob, Raquel G.,De Oliveira, Daniela H.,Peglow, Thiago J.,Nascimento, José E. R.,Bartz, Ricardo H.
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- Microwave-assisted aromatization of 1,3,5-trisubstituted 2-pyrazolines by silica-supported N-bromosuccinimide as a useful reagent under solvent free 'dry' condition
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An efficient aromatization of 1,3,5-trisubstituted 2-pyrazolines to theircorresponding pyrazoles by NBS was carried out under microwave irradiation and solvent-free conditions in moderate yields. It has also been observed that, by activating the NBS reage
- Azarifar, Davood,Maleki, Behrooz
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- N,N′,N,N′-tetrabromo-benzene-1,3-disulfonylamide as a novel reagent for oxidative aromatization of 1,3,5-trisubstituted pyrazolines under heterogeneous and solvent-free conditions
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1,3,5-Trisubstituted pyrazolines were converted to the corresponding pyrazoles in good yields under heterogeneous and solvent-free conditions by N,N′,N,N′-tetrabromo-benzene-1,3-disulfonylamide [TBBDA] at ambient temperature.
- Ghorbani-Vaghei, Ramin,Azarifar, Davood,Khazaei, Ardeshir,Maleki, Behrooz
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- Mild oxidation of 1,3,5-trisubstituted pyrazolines with N-bromo-sulphonamides
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1,3,5-Trisubstituted pyrazolines to pyrazoles are carried out efficiently in the presence of new reagents N,N,N′,N′-tetrabromo-benzene-1,3- disulfonylamine [TBBDA] and N,N′-dibromo-N,N′-1,2-ethanediylbis-(p- toluenesulphonamide) [BNBTS] in solvent-free conditions with catalytic amounts of SiO2 under microwave irradiation in high yields.
- Ghorbani-Vaghei, Ramin,Azarifar, Davood,Maleki, Behrooz
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- Trichloroisocyanuric acid as a novel oxidizing agent for the oxidation of 1,3,5-trisubstituted pyrazolines under both heterogeneous and solvent free conditions
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Trichloroisocyanuric acid is used as an effective oxidizing agent for the oxidation of 1,3,5-trisubstituted pyrazolines to their corresponding pyrazoles under both heterogeneous and also solvent free conditions with good yields at room temperature.
- Zolfigol, Mohammad Ali,Azarifar, Davood,Maleki, Behrooz
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- 4-(p-Chloro)phenyl-1,2,4-triazole-3,5-dione as a novel and reusable reagent for the oxidation of 1,3,5-trisubstituted pyrazolines under mild conditions
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4-(p-Chloro)phenyl-1,3,4-triazole-3,5-dione is used as an effective oxidizing agent for the oxidation of 1,3,5-trisubstituted pyrazolines to their corresponding pyrazoles under mild conditions with moderate to good yields at room temperature.
- Zolfigol, Mohammad Ali,Azarifar, Davood,Mallakpour, Shadpour,Mohammadpoor-Baltork, Iraj,Forghaniha, Ali,Maleki, Behrooz,Abdollahi-Alibeik, Mohammad
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- Silica-supported 1,3-dibromo-5,5-dimethylhydantoin (DBH) as a useful reagent for microwave-assisted aromatization of 1,3,5-trisubstituted pyrazolines under solvent-free conditions
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1,3,5-Trisubstituted pyrazolines are rapidly and conveniently oxidized to their corresponding pyrazoles by 1,3-dibromo-5,5-dimethylhydantoin (DBH) under microwave irradiation and solvent-free conditions. The presence of silica gel as a supporting agent is
- Azarifar, Davood,Zolfigol, Mohammad Ali,Maleki, Behrooz
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- Synthesis of 1: H -indazoles by an electrochemical radical Csp2-H/N-H cyclization of arylhydrazones
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The development of efficient and sustainable C-N bond-forming reactions to N-heterocyclic frameworks has been a long-standing interest in organic synthesis. In this work, we develop an electrochemical radical Csp2-H/N-H cyclization of arylhydrazones to 1H-indazoles. The electrochemical anodic oxidation approach was adopted to synthesize a variety of 1H-indazole derivatives in moderate to good yields. HFIP was not only employed as a solvent or the proton donor, but also can promote the formation of N free radicals. This synthetic methodology is operationally simple, and less expensive electrodes would be suitable for this chemistry. This journal is
- Alhumade, Hesham,Lei, Aiwen,Li, Dongting,Wan, Hao,Xia, Huadan,Yang, Liwen,Yi, Hong
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p. 665 - 668
(2022/01/22)
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- PEROVSKITES FOR PHOTOCATALYTIC ORGANIC SYNTHESIS
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Nature is capable of storing solar energy in chemical bonds via photosynthesis through a series of C—C, C—O and C—N bond-forming reactions starting from CO2 and light. Direct capture of solar energy for organic synthesis is a promising approach
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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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- TBHP/Cu(OAc)2 mediated oxidation of pyrazolines: A convenient method for the preparation of pyrazoles
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An efficient and simple oxidative protocol has been developed for the preparation of pyrazoles from pyrazolines mediated by TBHP/Cu(OAc)2 at room temperature. The present protocol has been successfully applied for the preparation of various pyrazole compounds from heterocyclic pyrazolines.
- Kolla, Sai Teja,Somanaboina, Ramya,Bhimapaka, China Raju
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supporting information
p. 1425 - 1432
(2021/02/27)
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- Structural requirements of 1-(2-pyridinyl)-5-pyrazolones for disproportionation of boronic acids
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We observed an unusual formation of four-coordinate boron(III) complexes from the reaction of 1-(2-pyridinyl)-5-pyrazolone derivatives with arylboronic acids in the basic media. The exact mechanism is not clear; however, the use of unprotected boronic acid and the presence of a bidentate ligand appeared to be the key structural requirements for the transformation. The results suggest that base-promoted disproportionation of arylboronic acid with the assistance of the [N,O]-bidentate ligation of 1-(2-pyridinyl)-5-pyrazolone should take place and facilitate the formation of pyrazole di-arylborinate. Experiments to obtain a deeper understanding of its mechanism are currently underway.
- Bae, Yunsoo,Cho, Joungmo,Han, Yohan,Lee, Hwajeong,Lee, Kee-In,Sadu, Venkata Subbaiah
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- Active Base Hybrid Organosilica Materials based on Pyrrolidine Builder Units for Fine Chemicals Production
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The catalytic activity of “pyrrolidine type” fragments included or anchored in the mesoporous silica supports or polymeric frameworks have been fully reported for enantioselective transformation. Nevertheless, low attention was focused on their catalytic abilities to perform base-catalyzed reaction. Accordingly, hybrid materials including pyrrolidine fragments in the mesoporous silica supports were prepared following different synthesis methods, such as micellar and fluoride sol-gel routes in absence of structural directing agents. Their great catalytic performance was explored for various base-catalyzed reactions to the formation of C?C bond through Knoevenagel, Claisen-Schmidt and Henry condensations under microwave irradiation. The benefits of microwave irradiation combined with suitable catalytic properties of pyrrolidine hybrid materials with strong base sites and high accessibility to active centers, allowed carrying out successfully base-catalyzed condensation reactions for the production of fine chemicals. Moreover, the hybrid catalyst exhibited high selectivity and good stability over different catalytic cycles contributing to environmental sustainability.
- Llopis, Sebastián,Velty, Alexandra,Díaz, Urbano
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p. 5012 - 5024
(2021/10/19)
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- Cycloaddition of Nitrile Imines with Enamides: An Approach to Functionalized Pyrazolines and Pyrazoles
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An efficient [3 + 2] cycloaddition of in situ generated nitrile imines with enamides has been established. A wide range of functionalized pyrazoline derivatives (53 examples) were obtained in moderate to good yields (up to 96%) under very mild conditions. This protocol features broad substrate scope, good functional group tolerance, and operational simplicity. Practical transformation of the products into useful pyrazoles via a one-pot process and the scalability of this protocol highlight the utility of this synthetic methodology.
- Tu, Liang,Gao, Limei,Wang, Xiaomeng,Shi, Ruijie,Ma, Rupei,Li, Junfei,Lan, Xiaoshuang,Zheng, Yongsheng,Liu, Jikai
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supporting information
p. 559 - 573
(2021/01/09)
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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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- Synthesis of 1,3,5-Trisubstituted Pyrazoles and Hydrazones Using Fe3O4?CeO2 Nanocomposite as an Efficient Heterogeneous Nanocatalyst
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Abstract: Pyrazoles and hydrazones, as two significant kinds of potentially bioactivecompounds, were produced with good to excellent yields by condensation ofβ-dicarbonyl compounds with hydrazines in aqueous media in the presence ofFe3O4?CeO2nanocomposite as an efficient heterogeneous nanocatalyst. The magneticnanocatalyst can readily be separated using an external magnet and reused atleast six times without significant loss in activity. The products werecharacterized by IR and 1H and13C NMR spectra.
- Hassani, H.,Jahani, Z.
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p. 485 - 490
(2020/04/27)
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- Photooxidation of 3,5-diaryl-1-phenyl-2-pyrazolines: Experimental and computational studies
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Photooxidation of various 2-pyrazolines is studied experimentally and computationally. Experimental results show that the electron-donating/withdrawing substituents increases/decreases the rate of this photoreaction. The proposed light-induced electron-tr
- Soltani, Marzieh,Memarian, Hamid Reza,Sabzyan, Hassan
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- Oxone-DMSO Triggered Methylene Insertion and C(sp2)-C(sp3)-H-C(sp2) Bond Formation to Access Functional Bis-Heterocycles
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Metal-free insertion of a methylene group was achieved for the construction of a new C(sp2)-C(sp3)-H-C(sp2) bond in order to prepare novel bis-heterocyclic scaffolds. The complete mechanistic investigations included experimental study and DFT calculations, and various symmetric and unsymmetric bis-pyrazoles as well as other pyrazole-based bis-heterocyclic molecules were prepared in moderate to high yields. Further modification of the bridged methylene group in the unsymmetric pyrazoles generated a chiral center to extend the scope of this method.
- Bharatam, Prasad V.,Dubey, Gurudutt,Hussain, Yaseen,Kour, Jaspreet,Sahoo, Subash C.,Sawant, Sanghapal D.,Venkateswarlu, Vunnam,Verma, Praveen K.
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p. 4951 - 4962
(2020/05/08)
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- System suitable for pyrazoline photocatalytic oxidation (by machine translation)
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The invention discloses a system suitable for the catalytic oxidation of pyrazoline, which is composed of a photo-sensitive catalyst, an oxidizing agent and various organic acids. To the present invention, TiO is supported by silica gel. 2 Powd
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Paragraph 0024-0027; 0032-0035
(2019/07/29)
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- Visible light mediated metal-free oxidative aromatization of 1,3,5-trisubstituted pyrazolines
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The visible light mediated oxidation of 1,3,5-trisubstituted pyrazolines under metal-free conditions was developed. Various substituted pyrazolines were oxidized to pyrazoles by irradiation with visible light/sunlight. A plausible mechanism was proposed f
- Annes, Sesuraj Babiola,Rajmohan, Rajamani,Ramesh, Subburethinam,Vairaprakash, Pothiappan
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supporting information
(2019/07/22)
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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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- Application and developing of iron-doped multi-walled carbon nanotubes (Fe/MWCNTs) as an efficient and reusable heterogeneous nanocatalyst in the synthesis of heterocyclic compounds
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Iron-doped multi-walled carbon nanotubes (Fe/MWCNTs) is an efficient, ecofriendly and reusable heterogeneous nanocatalyst for the one-pot synthesis of heterocyclic compounds including bis-spiro piperidines, piperidines, dihydro-2-oxopyrroles, pyrazoles and diazepines at room temperature with good to excellent yields. The heterogeneous nanocatalyst was fully characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP) and FT-IR analysis. Also, the structures of all prepared compounds were characterized by 1H NMR, 13C NMR, FT-IR, mass spectrometry (MS) and elemental analysis. The major advantages of these protocols are mild and green reaction conditions, short reaction times, clean reaction, operational simplicity, easy purification and good to excellent yields with the reusable heterogeneous nanocatalyst. The catalyst was ten recycled without significant loss of activity.
- Sharghi, Hashem,Aboonajmi, Jasem,Mozaffari, Mozhdeh,Doroodmand, Mohammad Mahdi,Aberi, Mahdi
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- Efficient Copper-Catalyzed Synthesis of Substituted Pyrazoles at Room Temperature
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An efficient method for the synthesis of pyrazoles through a copper-catalyzed condensation reaction has been developed. The new catalytic system not only maintained a broad substrate scope but was also active under acid-free reaction conditions, overcoming the conventional requirement for an acid-catalyzed system. Furthermore, the copper catalyst enabled this reaction to be performed at room temperature and in a short reaction time.
- Wang, Haifeng,Sun, Xiangli,Zhang, Shuangling,Liu, Guanglu,Wang, Chunjie,Zhu, Lili,Zhang, Hui
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supporting information
p. 2689 - 2692
(2018/12/14)
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- Application of Photoclick Chemistry for the Synthesis of Pyrazoles via 1,3-Dipolar Cycloaddition between Alkynes and Nitrilimines Generated In Situ
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The photochemical extrusion of gaseous nitrogen from 2,5-disubstituted tetrazoles to generate reactive nitrilimines in situ represents an efficient and attractive way to form dipoles that can be used to provide useful chemicals via 1,3-dipolar cycloadditions. The concept of “photoclick chemistry” already inspired numerous researchers, who exploited photochemical processes involving alkenes for the synthesis of adducts or the functionalization of biocompatible materials. The approach requires bioorthogonality, ease of access to the starting materials and operational simplicity. We report herein our investigations toward a photoclick reaction involving 2,5-disubstituted tetrazoles and alkynes as the dipolarophile for the synthesis of pyrazole derivatives. In addition to the numerous reports recently published on the synthesis of pyrazoles, we wish to add to the list a photochemical procedure that represents a mild and atom-economical alternative. Moreover, considering that such nitrilimines precursors can be accessed in one step from inexpensive and abundant starting materials and given the commercial availability of a broad spectrum of alkynes, we examined the scope of the photoclick reaction with respect to reactive partners, enabling the synthesis of a library of useful heteroaromatics.
- Remy, Richard,Bochet, Christian G.
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p. 316 - 328
(2018/01/27)
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- 13C NMR spectroscopy of heterocycles: 1-phenyl-3-aryl/t-butyl-5-arylpyrazoles
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A series of chalcones 1-12 were converted to pyrazolines (1Pi-12Pi) by reaction with phenylhydrazine followed by DDQ oxidation to produce the corresponding pyrazoles (1Pz-12Pz). Three 1-phenyl-3-t-butyl-5-arylpyrazoles (13Pz-15Pz) were synthesized using an analogous approach. Molecular modeling studies predicted the 5-aryl group of the pyrazoles for both series to have a torsion angle of 52°-54° whereas the 1-phenyl group was predicted to have 35°-37° torsion angles. The 3-aryl group was predicted to be essentially coplanar (-3°) with the pyrazole system in the first series. 13C NMR data for both series, 1Pz-12Pz and 13Pz-15Pz, were collected in DMSO-d6 at 50°C. A plot of the C4 chemical shifts for 1Pz-12Pz versus Hammet constants for 5-aryl substituents yielded a very good linear correlation (R2=0.96) with a slope of 1.5. The chemical shift data for C4 showed little or no dependence on 3-aryl substituents. The result for 13Pz-15Pz, despite only three points, was consistent with the first series results and yielded a ρ value of 2.0. Distal transmission of substituent effects (5-aryl groups) to C4 of the pyrazole system was reduced by roughly 50-60% of that of the analogous planar isoxazole system, but are not consistent with results for the similarly twisted 4-bromoisoxazoles.
- Hockstedler, Amy N.,Edjah, Beatrice A.,Azhar, Saajid Z.,Mendoza, Hadrian,Brown, Nicole A.,Arrowood, Hayley B.,Clay, Andrew C.,Shah, Anand B.,Duffek, Glenda M.,Cui, Jianmei,Baumstark, Alfons L.
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p. 125 - 131
(2017/04/14)
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- Method for efficiently preparing 1,3,5-trisubstituted pyrazole compound
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The invention discloses a method for efficiently preparing a 1,3,5-trisubstituted pyrazole compound. According to the method for efficiently preparing the 1,3,5-trisubstituted pyrazole compound, with metal palladium as a catalyst and triethylamine as an additive, aryl hydrazide hydrochloride, terminal alkyne and carbon monoxide are used as raw materials and react with one another under a heated condition in the atmosphere of oxygen to obtain the 1,3,5-trisubstituted pyrazole compound; and the reaction formula is formula (1). The method for efficiently preparing the 1,3,5-trisubstituted pyrazole compound realizes a method for preparing the 1,3,5-trisubstituted pyrazole compound by using palladium-catalyzed one-pot multi-component cascade reaction; and the method for efficiently preparing the 1,3,5-trisubstituted pyrazole compound has the advantages of simplicity, feasibility, simply and easy obtaining of raw materials and wide application prospect.
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Page/Page column 4; 5
(2017/08/29)
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- A Regioselective Approach to Trisubstituted Pyrazoles via Palladium-Catalyzed Oxidative Sonogashira-Carbonylation of Arylhydrazines
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A palladium-catalyzed oxidative carbonylation of arylhydrazines and alkynes with balloon pressure CO/O2 to afford trisubstituted pyrazoles in a one-pot manner has been developed. The formation of trisubstituted pyrazoles involves a sequential C-N bond cleavage, carbonylation, Sonogashira coupling, Michael addition, and intramolecular condensation cyclization tandem process. An unprecedented oxidative Sonogashira-carbonylation reaction of arylhydrazine plays a key role for such a facile approach to pyrazoles.
- Tu, Yongliang,Zhang, Zhenming,Wang, Tao,Ke, Jiamei,Zhao, Junfeng
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supporting information
p. 3466 - 3469
(2017/07/15)
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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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- 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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p. 3169 - 3181
(2016/04/05)
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- Synthesis, characterization and aggregation induced enhanced emission properties of tetraaryl pyrazole decorated cyclophosphazenes
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A series of cyclotriphosphazenes N3P3(O-C6H4-C3N2-(C6H5)3)6 (3), N3P3(O2C12H8)(O-C6/
- Mukundam, Vanga,Dhanunjayarao, Kunchala,Mamidala, Ramesh,Venkatasubbaiah, Krishnan
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supporting information
p. 3523 - 3530
(2016/05/19)
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- Tris(pentafluorophenyl)borane-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles
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Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition-metal-based catalysts. Herein, a borane-catalyzed, metal-free acceptorless dehydrogenation of saturated N-heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N-heteroarenes in up to quantitative yield. Specifically, the present metal-free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal-catalyzed systems. This protocol can thus be regarded as the first example of metal-free acceptorless dehydrogenation in synthetic organic chemistry.
- Kojima, Masahiro,Kanai, Motomu
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supporting information
p. 12224 - 12227
(2016/10/13)
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- Visible light catalyzed aromatization of 1,3,5-triaryl-2-pyrazolines by platinum(II) polypyridyl complex under oxidant-free condition
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With visible light (λ=450 nm) irradiation of a catalytic amount of platinum(II) terpyridyl complex, 1,3,5-triaryl-2-pyrazolines can be smoothly converted to their corresponding pyrazoles and hydrogen in quantitative yields with no use of any oxidant at ro
- Ye, Pan,Wang, Deng-Hui,Chen, Bin,Meng, Qing-Yuan,Tung, Chen-Ho,Wu, Li-Zhu
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p. 175 - 179
(2016/02/16)
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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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- Cycloisomerization of acetylenic oximes and hydrazones under gold catalysis: Synthesis and cytotoxic evaluation of isoxazoles and pyrazoles
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The synthesis of substituted isoxazoles and pyrazoles through a general cycloisomerization methodology has been reported. The capability of gold(III) chloride to promote cycloisomerization of both α, β-acetylenic oximes and α, β-acetylenic hydrazones is t
- Jeyaveeran,Praveen, Chandrasekar,Arun,M Prince,Perumal
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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 Study of Boratriazaroles: An Underdeveloped Class of Heterocycles
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Boratriazaroles were discovered in the late 1960s, and since then, a variety of substituted boratriazarole derivatives have been prepared. However, no study has compared the properties of these BN heterocycles with their carbon-based analogues. In this work, we have prepared a series of boratriazarole derivatives and have investigated how structural variations in the five-member heterocycle affect photophysical and electronic properties. Boratriazaroles exhibit absorption and emission spectra comparable to those of their azacycle analogues but have a markedly lower quantum yield. The quantum yield can be increased with the incorporation of a 2-pyridyl substitution on the boratriazaroles, and the structural and optoelectronic properties are further influenced by the nature of the B-aryl substituent. Introducing an electron-deficient p-cyano group on the B-phenyl substituent creates a twisted intramolecular charge transfer state that causes a large Stokes shift and positive solvatochromism. Our work should serve to guide future synthetic efforts toward the application of boratriazaroles in materials science.
- Liew, Sean K.,Holownia, Aleksandra,Tilley, Andrew J.,Carrera, Elisa I.,Seferos, Dwight S.,Yudin, Andrei K.
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p. 10444 - 10453
(2016/11/17)
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- Studies on the antioxidant activities of mechanochemically synthesized 1-aryl-3,5-Bis(Styryl) pyrazoles as curcuminoids derived CNB 001 analogs
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1-Aryl-3,5-bis(styryl)pyrazoles, as analogs of CNB 001, a well investigated, curcumin derived neuroprotector, have been accessed through rapid, energy efficient mechanochemical synthesis starting from curcuminoids. A study of their anti-oxidant activity i
- Sherin, Daisy R.,Rajasekharan, Kallikat N.
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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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p. 3604 - 3607
(2016/07/21)
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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
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- Synthesis of a cyclometalated 1,3,5-triphenylpyrazole palladium dimer and its activity towards cross coupling reactions
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A phosphine free 1,3,5-triphenylpyrazole acetate-bridged palladacycle was prepared from simple commercially available starting materials. The activity of the palladacycle in the Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions was evaluated. The palladacycle precatalyst shows a wide substrate scope, both in Mizoroki-Heck as well as in Suzuki-Miyaura cross-coupling reactions using low catalyst loadings viz., 0.2 mol% and 0.1 mol% respectively.
- Mamidala, Ramesh,Mukundam, Vanga,Dhanunjayarao, Kunchala,Venkatasubbaiah, Krishnan
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p. 5805 - 5809
(2015/03/30)
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- AIEE phenomenon: Tetraaryl vs. triaryl pyrazoles
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Tetraarylpyrazoles are synthesized from commercially available materials in three steps and found to exhibit Aggregation Induced Emission Enhancement (AIEE) characteristics. Removing one aryl unit from tetraarylpyrazole leads to Aggregation Caused Quenching (ACQ), thus the number of aryl groups plays an important role in exploring such a phenomenon.
- Mukherjee, Sayani,Salini,Srinivasan,Peruncheralathan
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supporting information
p. 17148 - 17151
(2015/12/05)
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- Synthesis and anticancer activity of 1,3,5-triaryl-1H-pyrazole
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Previous studies demonstrated that some pyrazole derivatives could be considered as potential anticancer agents. A series of 1,3,5-triaryl-1H-pyrazole derivatives were prepared by the reaction of phenylhydrazin and different chalcones. The previous classi
- Ghadbeigi, Sajad,Ostad, Seyed Nasser,Shafiee, Abbas,Amini, Mohsen
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p. 754 - 759
(2015/10/05)
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- Transition-Metal-Free N-Arylation of Pyrazoles with Diaryliodonium Salts
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A new synthetic method was developed for the N-arylation of pyrazoles using diaryliodonium salts. The transformation does not require any transition-metal catalyst and provides the desired N-arylpyrazoles rapidly under mild reaction condition in the presence of aqueous ammonia solution as a mild base without the use of inert atmosphere. The chemoselectivity of unsymmetric diaryliodonium salts was also explored with large number of examples.
- Gonda, Zsombor,Novák, Zoltán
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supporting information
p. 16801 - 16806
(2015/11/16)
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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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- Iron-catalyzed aerobic oxidative aromatization of 1,3,5-trisubstituted pyrazolines
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A simple and high yielding method for the synthesis of tri-substituted pyrazoles via iron(III) catalyzed aerobic oxidative aromatization of pyrazolines has been reported. The process demonstrates a variety of functional group tolerance.
- Ananthnag, Guddekoppa S.,Adhikari, Adithya,Balakrishna, Maravanji S.
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supporting information
p. 240 - 243
(2013/12/04)
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- 3,4-Dihydro-2H-pyran promoted aerobic oxidative aromatization of 1,3,5-trisubstituted pyrazolines and Hantzsch 1,4-dihydropyridines
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An unprecedented facile oxidation of 1,3,5-trisubstituted pyrazolines and Hantzsch 1,4-dihydropyridines (DHPs) to the corresponding pyrazoles and pyridines was observed, mediated by 3,4-dihydro-2H-pyran in air. The reaction showed excellent reactivity, functional group tolerance, and high yield without using any metal and/or halogen based oxidizing agents.
- Banerjee, Dipanwita,Kayal, Utpal,Karmakar, Rajiv,Maiti, Gourhari
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supporting information
p. 5333 - 5337
(2015/01/08)
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- Facile one-pot synthesis of 1,3,5-trisubstituted pyrazoles from α,β-enones
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A practical and efficient one-pot synthesis of 1,3,5-trisubstituted pyrazoles from α,β-enones and arylhydrazine hydrochlorides has been developed. The pyrazoles were formed via a tandem formation of the corresponding pyrazolines and an acid-catalyzed aerobic oxidation process.
- Yu, Jin,Kim, Ko Hoon,Moon, Hye Ran,Kim, Jae Nyoung
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p. 1692 - 1696
(2014/07/07)
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- SAR studies of differently functionalized chalcones based hydrazones and their cyclized derivatives as inhibitors of mammalian cathepsin B and cathepsin H
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Cathepsins have emerged as potential drug targets for melanoma therapy and engrossed attention of researchers for development and evaluation of cysteine cathepsin inhibitors as cancer therapeutics. In this direction, we have designed, synthesized, and ass
- Raghav, Neera,Singh, Mamta
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supporting information
p. 4233 - 4245
(2014/08/18)
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- Energy efficiency of heterogeneous catalytic microwave-assisted organic reactions
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The energy efficiency of microwave-assisted reactions was studied under heterogeneous catalytic conditions. Based on earlier publications the choice of catalyst was a semi-synthetic montmorillonite K-10. This material absorbs microwave energy effectively and is an excellent catalyst for microwave-assisted organic synthesis. The energy consumption of six different types of K-10 catalyzed reactions with multiple substrates and varied experimental parameters were determined under microwave irradiation and conventional heating. The parallel reactions were carried out under the same conditions to ensure the comparability of the data. While in the majority of the studied reactions, the microwave-assisted method appeared to be more energy efficient by various extents, in one case the conventional heating was found to be more efficient. The data, in agreement with a previous report, indicate that reactions should be studied on a case-by-case basis and that an automatic green label for microwave-assisted reactions is not warranted. This journal is the Partner Organisations 2014.
- Cho, Hyejin,Toeroek, Fanni,Toeroek, Bela
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p. 3623 - 3634
(2014/07/08)
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- Copper-mediated pyrazole synthesis from 2,3-allenoates or 2-alkynoates, amines and nitriles
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An efficient copper-mediated three-component reaction of 2,3-allenoates or 2-alkynoates, amines, and nitriles affording fully substituted pyrazoles with a very nice diversity has been developed. A tandem conjugate addition, 1,2-addition, and N-N bond formation mechanism has been proposed for this diverse synthesis of pyrazoles based on mechanistic studies.
- Chen, Bo,Zhu, Can,Tang, Yang,Ma, Shengming
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p. 7677 - 7679
(2014/07/08)
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- Formyl substituent at C-4 of pyrazoles: A temporary protecting group for regioselective palladium-catalyzed direct arylation at C-5
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Pyrazoles with an aldehyde function at C-4 underwent a palladium-catalyzed direct arylation reaction to provide a regioselective approach to 5-aryl-substituted pyrazoles. The reaction proceeds in moderate to high yields with a variety of aryl bromides in the presence of 2 mol-% of Pd(OAc) 2 as the catalyst. The use of an aldehyde function at C-4 of the pyrazoles presents several advantages: (1) 4-formylpyrazoles are easily prepared from hydrazine derivatives, ketones, and N,N-dimethylformamide (DMF), (2) the control of the regioselectivity of the arylation at C-5 of the pyrazole, (3) the aldehyde substituent can easily be transformed into a wide variety of other substituents, and (4) the formyl group can be considered a temporary protecting group, as it can be removed by a straightforward reaction. Copyright
- Smari, Imen,Youssef, Chiraz,Yuan, Kedong,Beladhria, Anissa,Ben Ammar, Hamed,Ben Hassine, Bechir,Doucet, Henri
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p. 1778 - 1786
(2014/03/21)
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- Formyl Substituent at C-4 of Pyrazoles: A Temporary Protecting Group for Regioselective Palladium-Catalyzed Direct Arylation at C-5
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Pyrazoles with an aldehyde function at C-4 underwent a palladium-catalyzed direct arylation reaction to provide a regioselective approach to 5-aryl-substituted pyrazoles. The reaction proceeds in moderate to high yields with a variety of aryl bromides in the presence of 2 mol-% of Pd(OAc)2 as the catalyst. The use of an aldehyde function at C-4 of the pyrazoles presents several advantages: (1) 4-formylpyrazoles are easily prepared from hydrazine derivatives, ketones, and N,N-dimethylformamide (DMF), (2) the control of the regioselectivity of the arylation at C-5 of the pyrazole, (3) the aldehyde substituent can easily be transformed into a wide variety of other substituents, and (4) the formyl group can be considered a temporary protecting group, as it can be removed by a straightforward reaction.
- Smari, Imen,Youssef, Chiraz,Yuan, Kedong,Beladhria, Anissa,Ben Ammar, Hamed,Ben Hassine, Bechir,Doucet, Henri
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p. 1778 - 1786
(2015/10/05)
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- Four-component synthesis of β-enaminone and pyrazole through phosphine-free palladium-catalyzed cascade carbonylation
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The carbonylative domino synthesis of enaminones and pyrazoles has been performed with the N?N bidentate palladium catalyst to achieve excellent selectivity. These results have confirmed that the carbonylative Sonogashira coupling of iodobenzenes with ter
- Shi, Lijun,Xue, Liqin,Lang, Rui,Xia, Chungu,Li, Fuwei
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p. 2560 - 2566
(2015/04/14)
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- Molecular iodine: A green and inclusive catalyst for the synthesis of highly functionalized 1,3,5-trisubstituted pyrazoles in aqueous medium
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A library of 1,3,5-trisubstituted pyrazoles was synthesized in excellent yields from the reaction of aldehyde, phenylhydrazine and alkynes in the presence of iodine via an eco-friendly, simple process performed in aqueous medium. This single pot transformation generates new CN, C-C, C-N bonds and proceeds by a domino reaction involving the formation of Schiff base, Mannich addition and finally intramolecular cyclisation. The Royal Society of Chemistry 2014.
- Rai, Pratibha,Srivastava, Madhulika,Singh, Jagdamba,Singh, Jaya
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p. 779 - 783
(2014/01/06)
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- Synthesis of 1 H-indazoles and 1 H-pyrazoles via FeBr3/O 2 mediated intramolecular C-H amination
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A new synthesis of substituted 1H-indazoles and 1H-pyrazoles from arylhydrazones via FeBr3/O2 mediated C-H activation/C-N bond formation reactions is reported. The corresponding 1,3-diaryl-substituted indazoles and trisubstituted pyr
- Zhang, Tianshui,Bao, Weiliang
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p. 1317 - 1322
(2013/04/10)
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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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p. 213 - 219
(2013/07/26)
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