- Copper-Mediated Domino Cyclization/Trifluoromethylation of Propargylic N-Hydroxylamines: Synthesis of 4-Trifluoromethyl-4-isoxazolines
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A Cu(OTf)2-mediated synthesis of trifluoromethylated 4-isoxazolines is described. In one step from readily available propargylic N-hydroxylamines, a domino 5-endo-dig cyclization, followed by trifluoromethylation, takes place to construct the 4-isoxazoline core with concomitant installation of the CF3 group at the C-4 position. Such compounds could also be useful precursors for the preparation of α-trifluoromethyl β-amino ketones.
- Wang, Quande,Tsui, Gavin Chit
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- Nitrosylsulfuric acid as an oxidant in the synthesis of 3,5-diarylisoxazoles
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By six examples, it was demonstrated that nitrosylsulfuric acid can be successfully used for oxidation of 3,5-diaryl-4,5-dihydroisoxazoles to the corresponding 3,5-diarylisoxazoles. If the starting isoxazolines contain the aromatic substituents activated towards electrophilic substitution, nitration of both newly formed isoxazole and substituted benzene rings occurred.
- Bondarenko,Komarov,Kuznetsova,Nikolaeva,Gavrilova, A. Yu.,Zyk
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- One-pot synthesis of 5-phenylsulfonyl-3-aroylisoxazolines and 3-aroylisoxazoles from alkynes and (phenylsulfonyl)ethene
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Iron(III) nitrate-assisted cycloaddition of (phenylsulfonyl)ethene to arylacetylenes in the presence of KI affords 5-phenylsulfonyl-3-aroylisoxazolines whose treatment with K2CO3 provides 4,5-unsubstituted 3-aroylisoxazoles. Both synthetic steps can be performed in a one-pot manner.
- Wang, Liang,Zhang, Nana
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- Palladium-Catalyzed Cascade Cyclization/Alkynylation and Alkenylation of Alkynone O-Methyloximes with Terminal Alkynes
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A palladium-catalyzed cascade cyclization for the assembly of polyfunctionalized isoxazoles derivatives has been accomplished. This new protocol exhibits mild conditions, high efficiency, good functional group tolerance and broad substrate scope. Remarkably, the easy availability of starting materials along with the efficiency of the present strategy provides a new tool for the construction of structurally diverse isoxazole derivatives, becoming a promising application in synthetic and pharmaceutical chemistry. (Figure presented.).
- Li, Jianxiao,Hu, Miao,Li, Chunsheng,Li, Can,Li, Jiawei,Wu, Wanqing,Jiang, Huanfeng
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- Aerobic oxidative synthesis of 3,5-disubstituted isoxazoles directly from α,β-unsaturated ketones
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Using an efficient aerobic oxidative method, the synthesis of ten 3,5-disubstituted isoxazoles by treatment of α,β-unsaturated ketones with hydroxylamine and NaOH at room temperature has been achieved.
- Li, Zheng,Wen, Gong,Fu, Rugang,Yang, Jingya
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Read Online
- Nitrosylsulfuric acid as a tandem reagent in the synthesis of 3,5-diarylisoxazoles from 1,2-diarylcyclopropanes
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It was demonstrated that nitrosylsulfuric acid can be successfully used as a tandem nitrosating and oxidizing agent in the synthesis of 3,5-diarylisoxazoles from 1,2-diarylcyclopropanes. The reaction proceeds highly regioselectively in the case of symmetr
- Bondarenko,Komarov,Karetnikov,Nikolaeva,Zyk
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- 5-Substituted pyridylisoxazoles as effective inhibitors of platelet aggregation
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A series of 5-substituted 3-pyridylisoxazoles were synthesized using [3+2] cycloaddition of nitrile oxides to alkynes with variation of substituents at position 5 of the isoxazole ring without additional synthetic stages and with retention of 2-pyridyl-, 3-pyridyl, and 4-pyridyl substituents at position 3 of the isoxazole ring. Substituted pyridylisoxazoles are the potential antiaggregatory agents showing in vitro activity in the concentration range from 1?10-6 mol L-1 to 1?10-4 mol L-1 toward the human platelet rich blood plasma with arachidonic acid being used as the inductor of aggregation. These compounds do not act as cyclooxygenase or thromboxane synthase inhibitors, nor as thrombin inhibitors.
- Demina,Khodonov,Sinauridze,Shvets,Varfolomeev
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- 3, 5-disubstituted isoxazole derivative and synthesis method thereof
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The invention provides a 3, 5-disubstituted isoxazole derivative and a synthesis method thereof, and belongs to the technical field of organic synthesis medicines and medical intermediates. The method comprises the following steps: adding a proper solvent
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Paragraph 0011; 0023-0024
(2021/08/14)
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- Green preparation method of isoxazole compound participating in water-soluble vitamin E
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The invention provides a green synthesis method of an isoxazole compound represented by the formula (III), wherein the aldehyde oxime compound represented by the formula (I) is a substrate and is in an aqueous solution of a surfactant with a mass concentration 1 wt % - 5 wt % in N - chlorosuccinimide. The alkyne compound represented by the formula (II) is reacted 6 - 16h at room temperature under the common action of the basic substance, and the resulting reaction solution is post-treated to obtain the isoxazole compound represented by the formula (III). Water serves as a reaction solvent, the use amount of the organic solvent is reduced, and zero emission of the solvent is realized.
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Paragraph 0042-0068; 0164-0174
(2021/11/03)
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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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- Palladium-Catalyzed Sequential Cyclization/Functionalization of Oxime Ethers with Unactivated Vinyl Ethers for Tunable Assembly of Structurally Diverse Isoxazoles
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A novel and viable palladium-catalyzed sequential cyclization/functionalization of alkynone O-methyloximes with unactivated vinyl ethers under aerobic conditions was described. The structure of the products could be successfully controlled by varying the nature of the substituents of the vinyl ethers. This new approach provides a convenient and straightforward synthetic protocol for the preparation of structurally diverse 4-(1-alkoxyvinyl)-isoxazoles and 4-vinylisoxazoles in moderate to good yields with highly regioselectivity. Remarkably, this protocol can be performed on a gram scale, showing the promising application in synthetic and pharmaceutical chemistry.
- Li, Jianxiao,Lin, Zidong,He, Dan,Wu, Wanqing,Jiang, Huanfeng
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p. 3285 - 3291
(2021/10/14)
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- TEMPO-Mediated Selective Synthesis of Isoxazolines, 5-Hydroxy-2-isoxazolines, and Isoxazoles via Aliphatic δ-C(sp3)-H Bond Oxidation of Oximes
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Selective synthesis of three different bioactive heterocycles; isoxazolines, 5-hydroxy-2-isoxazolines and isoxazoles from the same starting material using TEMPO (2,2,6,6-Tetramethylpiperidin-1-oxyl) as a radical initiator is reported. Selectivity was achi
- Mondal, Santanu,Biswas, Sourabh,Ghosh, Krishna Gopal,Sureshkumar, Devarajulu
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p. 2439 - 2446
(2021/08/03)
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- Synthesis of isoxazoles via cyclization of β-fluoro enones with sodium azide
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A practical method for the synthesis of 3,5-disubstituted isoxazoles via cyclization of β-fluoro enones with sodium azide was disclosed. Density functional theory (DFT) calculation indicated that both (1) the azirine formation followed by intramolecular rearrangement and (2) direct enolate O-attack via 5-exo-trig cyclization of vinyl azide were possible for the isoxazole formation.
- Li, Liangkui,Huang, Shiqing,Mao, Kuantao,Lv, Leiyang,Li, Zhiping
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- Unusual Reactivity of 4-Vinyl Isoxazoles in the Copper-Mediated Synthesis of Pyridines, Employing DMSO as a One-Carbon Surrogate
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An efficient protocol for the synthesis of nicotinate derivatives and tetrasubstituted pyridines through a copper-mediated cleavage of isoxazoles has been developed. The highlight of the work is the observation of an unusual reactivity of 4-vinyl isoxazoles under the reaction conditions. DMSO serves as a one-carbon surrogate generating an active methylene group during the reaction to form two C-C bonds. This protocol provides a facile and an expeditious approach for the assembly of densely substituted N-heterocyclic compounds.
- Kumar, Pravin,Kapur, Manmohan
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supporting information
p. 5855 - 5860
(2020/07/30)
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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
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supporting information
p. 9751 - 9756
(2020/12/21)
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- A Reusable CNT-Supported Single-Atom Iron Catalyst for the Highly Efficient Synthesis of C?N Bonds
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C?N bond formation is regarded as a very useful and fundamental reaction for the synthesis of nitrogen-containing molecules in both organic and pharmaceutical chemistry. Noble-metal and homogeneous catalysts have frequently been used for C?N bond formatio
- Baell, Jonathan B.,Ding, Qifeng,Huang, Fei,Huang, He,Xu, Mingjie,Yu, Yang,Zhang, Lihui,Zheng, Jian-Guo
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- Synthesis of 2-Isoxazoline N-Oxides by Copper-Mediated Radical Annulation of Alkenes with α-Nitrobenzyl Bromides
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Copper-mediated [3 + 2] annulation of alkenes with α-nitrobenzyl bromides has been developed. The reaction is promoted simply by a copper salt to produce the corresponding 2-isoxazoline N-oxides with perfect regioselectivity. The present method can be conducted under mild conditions, affording a diverse array of 2-isoxazoline N-oxides. The obtained products can readily be converted to the related heterocycles such as 2-isoxazoline and isoxazole. A radical-polar crossover pathway initiated by single-electron transfer from nitronate to a copper salt is proposed.
- Iwasaki, Masayuki,Ikemoto, Yuichi,Nishihara, Yasushi
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p. 7577 - 7580
(2020/10/09)
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- Rhodium-Catalyzed Cascade Annulative Coupling of 3,5-Diarylisoxazoles with Alkynes
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A rhodium-catalyzed cascade annulative coupling of 3,5-diarylisoxazoles with three equivalents of an alkyne proceeds smoothly in the presence of a Cu(II) oxidant, where the sequential construction of isoquinoline and naphtho[1,8- bc ]pyran frameworks connected by a biaryl linkage is achieved by a single operation. Most of the obtained polycyclic compounds exhibit visible fluorescence in both the solution and the solid state. The hexaphenylated isoquinoline-naphthopyran conjugate (R = Ph) as a representative product shows a green emission which can be turned off by making an isoquinolinium salt with an acid. The emission is also reversibly turned on by treatment with a base.
- Noguchi, Teppei,Nishii, Yuji,Miura, Masahiro
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p. 258 - 270
(2019/01/04)
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- Catalyst control in positional-selective C-H alkenylation of isoxazoles and a ruthenium-mediated assembly of trisubstituted pyrroles
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High levels of catalyst control are demonstrated in determining the positional selectivity in C-H alkenylation of isoxazoles. A cationic rhodium-mediated, strong-directing group promotes C(sp2)-H activation at the proximal aryl ring whereas, the palladium-mediated electrophilic metallation leads to the C(sp2)-H activation at the distal position of the directing group. Synthetic elaboration of this C-H alkenylation product via ruthenium and copper co-catalysis leads to an efficient method for the assembly of densely substituted pyrroles.
- Kumar, Pravin,Kapur, Manmohan
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supporting information
p. 2134 - 2138
(2019/03/26)
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- Synthesis of 3,5-Disubstituted Isoxazoles through a 1,3-Dipolar Cycloaddition Reaction between Alkynes and Nitrile Oxides Generated from O-Silylated Hydroxamic Acids
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In this paper, we report the regioselective synthesis of 3,5-disubstituted isoxazoles by 1,3-dipolar cycloaddition between alkynyl dipolarophiles and nitrile oxide dipoles generated in-situ from O-silylated hydroxamic acids in the presence of trifluoromethanesulfonic anhydride and NEt3. Thanks to the mild, metal-free and oxidant-free conditions that this strategy offers, the reaction was successfully applied to a wide variety of alkynyl dipolarophiles, demonstrating the tolerance of this approach to diverse functional groups. In particular, we have shown that the method was compatible with biological molecules such as peptides and peptide nucleic acids (PNA). This protocol constitutes another example of metal-free 1,3-dipolar cycloaddition leading to the regioselective formation of isoxazoles.
- Carloni, Laure-Elie,Mohnani, Stefan,Bonifazi, Davide
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p. 7322 - 7334
(2019/11/05)
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- Intermolecular Multiple Dehydrogenative Cross-Couplings of Ketones with Boronic Acids and Amines via Copper Catalysis
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An efficient and versatile oxidative coupling reaction was developed for the synthesis of valuable β-functionalized unsaturated ketones and meta-substituted phenols. In the case of intramolecular reactions, achieving rapid molecular complexity through multiple dehydrogenative couplings is already a well-established strategy. Herein, we report an intermolecular multiple dehydrogenative coupling between ketones and nucleophilic amines or boronic acids using inexpensive copper(I) oxide as a catalyst. This method provides a facile access to highly desirable chemical products such as α,β-unsaturated ketones, enaminones, and synthetically relevant meta-substituted phenols. (Figure presented.).
- Wang, Tianzhang,Chen, Guowei,Lu, Yu-Jing,Chen, Qian,Huo, Yanping,Li, Xianwei
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p. 3886 - 3892
(2019/07/19)
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- An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes
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α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N- or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further, proper functionalization of α-haloketoximes and a change of conditions allowed the chemoselective synthesis of chromenone-oximes as well as rearranged isoxazoles, thereby realizing a diversity-oriented synthesis.
- Khairnar, Pankaj V.,Lung, Tsai-Hui,Lin, Yi-Jung,Wu, Chi-Yi,Koppolu, Srinivasa Rao,Edukondalu, Athukuri,Karanam, Praneeth,Lin, Wenwei
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p. 4219 - 4223
(2019/06/17)
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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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- Electrochemical synthesis of enaminones: Via a decarboxylative coupling reaction
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An environmentally benign and efficient electrochemical synthesis of enaminones via a decarboxylative coupling reaction of α-keto acids using n-Bu4NI as a redox catalyst and electrolyte under constant current electrolysis in an undivided cell is reported. A broad vinyl azide substrate scope and high functional group tolerance are observed. A gram-scale reaction further demonstrates the practicability of the protocol. The results of cyclic voltammetry and control experiments indicate that I2 is likely the active species to initiate the oxidative decarboxylation via an acyl hypoiodite intermediate.
- Kong, Xianqiang,Liu, Yulong,Lin, Long,Chen, Qianjin,Xu, Bo
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p. 3796 - 3801
(2019/07/31)
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- Preparation method of isoxazole derivative
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The invention relates to a preparation method of an isoxazole derivative, which comprises the following steps of mixing an propargyl alcohol derivative, a halogen source, an acid and a solvent, and heating to react; adding the hydroxylamine into the react
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Paragraph 0114-0118
(2019/12/02)
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- Trichloroisocyanuric acid mediated one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones
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A facile one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones and hydroxylamine hydrochloride is reported. The reaction is efficiently promoted by trichloroisocyanuric acid (TCCA) to afford the desired products, mostly in high yields and
- Bhatt, Ashish,Singh, Rajesh K.,Kant, Ravi
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p. 1083 - 1091
(2019/04/01)
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- Assembly of Functionalized 4-Alkynylisoxazoles by Palladium-Catalyzed Three-Component Cascade Cyclization/Alkynylation
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A novel N-heterocyclic carbene (NHC)-palladium-catalyzed three-component cascade cyclization/alkynylation for the synthesis of structurally diverse 4-alkynylisoxazoles was efficiently developed in ionic liquids. The operational simplicity, without additives, no additional ligands, and 0.5 mol % catalyst loading under air are some of the attractive features of this present protocol.
- Li, Jianxiao,Huang, Ruikang,Li, Can,Lin, Shao,Wu, Wanqing,Jiang, Huanfeng
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p. 2309 - 2315
(2019/06/24)
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- A convenient one-pot synthesis of 3,5-diarylisoxazoles via oxidative cyclisation using catalytic CuBr2 and oxone
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A facile one-pot synthesis of 3,5-diarylisoxazoles from α,β-unsaturated ketones and hydroxylamine hydrochloride is reported. The reaction is efficiently promoted by catalytic CuBr2 and Oxone to afford the desired products mostly in high yields
- Bhatt, Ashish,Singh, Rajesh K.,Kant, Ravi
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supporting information
p. 1143 - 1147
(2019/03/26)
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- General Platform for the Conversion of Isoxazol-5-ones to 3,5-Disubstituted Isoxazoles via Nucleophilic Substitutions and Palladium Catalyzed Cross-Coupling Strategies
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A general platform for the conversion of isoxazol-5-ones to 3,5-disubstituted isoxazoles has been developed via a two-step strategy. The first step leads to the formation of 5-(pseudo)halogenated isoxazoles, while in the second, a variety of heteroalkyl-, heteroaryl-, alkyl-, alkenyl-, alkynyl- and aryl-chains can be installed via nucleophilic substitutions or palladium catalyzed cross-coupling reactions.
- Fernandes, Alessandra A. G.,da Silva, Amanda F.,Okada, Celso Y.,Suzukawa, Vitor,Cormanich, Rodrigo A.,Jurberg, Igor D.
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p. 3022 - 3034
(2019/05/17)
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- NH2OH-HCl-Mediated Umpolung α-Methylsulfonylation of α-Sulfonyl Ketones with Methylsulfoxides: Synthesis of α,β-Bis-sulfonyl Arylketones
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In this paper, a novel and efficient route for the synthesis of α,β-bis-sulfonyl arylketones via an NH2OH-HCl-mediated intermolecular umpolung α-methylsulfonylation of α-sulfonyl ketones with methylsulfoxides is described. A plausible mechanism is proposed and discussed. Various reaction conditions for this efficient, one-pot, environmentally friendly transformation were investigated.
- Chang, Meng-Yang,Chen, Han-Yu,Tsai, Yu-Lin
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supporting information
p. 1832 - 1836
(2019/03/07)
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- Copper-catalysed synthesis of 3,5-disubstituted isoxazoles enabled by pyridinyl benzimidazol (PBI) as a bidentate N-chelating ligand under mild conditions
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In this paper, we introduced pyridinyl benzimidazol (PBI) as an easy-to-handle and bidentate N-chelating ligand that promote clean synthesis of 3,5-disubstituted isoxazoles in the presence of copper acetate as catalyst. This catalytic approach initiates with the hydroxyamination of aldehydes followed by chlorination and then generation of nitrile oxide which subsequently undergoes click-type [3?+?2]-dipolar cycloaddition with alkynes to give isoxazoles. This method provides an alternative green process to construct isoxazole derivatives.
- Khalifeh, Reza,Shahriarpour, Fatemeh,Sharghi, Hashem,Aberi, Mahdi
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p. 813 - 821
(2018/03/01)
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- Complementary regioselective synthesis of 3,5-disubstituted isoxazoles from ynones
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Two regioselective synthetic routes towards 3,5-disubstituted isoxazoles from ynones are reported. One route takes place via first converting the ynones to ynone O-methyl oximes, followed by a palladium-catalyzed intramolecular cyclization. The other invo
- Liu, Xiaochen,Hong, Dongsub,She, Zhigang,Hersh, William H.,Yoo, Barney,Chen, Yu
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p. 6593 - 6606
(2018/10/05)
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- Synthesis of 3,5-diarylisoxazole derivatives and evaluation of in vitro trypanocidal activity
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Chagas disease is included in the neglected tropical diseases list and is endemic to 21 Latin American countries. The two drugs currently available for treating Chagas disease are nifurtimox and benznidazole and both result in many significant side effects. The study describes the synthesis and biological evaluation of 3,5-disubstituted isoxazoles. Isoxazoles were obtained by reaction of flavones and hydroxylamine and either alkylated at the free hydroxyl group and/or nitrated at the isoxazole ring. These compounds were evaluated for their in vitro anti-Trypanosoma cruzi activity against trypomastigote and amastigote forms of the parasite in T. cruzi-infected cell lineages. Benznidazole was used as a reference compound for the in vitro assay and mammalian L929 cells were employed to evaluate cytotoxicity. A majority of the compounds tested were very active and the most active isoxazole against amastigote and trypomastigotes of T. cruzi was slightly more potent than the current medicine benznidazole.
- De Souza, Aline A. N.,Xavier, Viviane F.,Coelho, Gleicekelly S.,Sales Junior, Policarpo A.,Romanha, Alvaro J.,Murta, Silvane M. F.,Carneiro, Claudia M.,Taylor, Jason G.
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p. 269 - 277
(2017/12/08)
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- Structural and morphological aspects of small 3,5-disubstituted isoxazoles
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The structural and morphological features of small 3,5-disubstituted isoxazoles/isoxazolines are presented and discussed in the light of thermal analysis by differential scanning calorimetry (DSC), polarized optical microscopy (POM) technique, combined with single crystal X-ray diffraction and molecular modeling. The title compounds obtained were also characterized by 1H, 13C and 19F NMR. Two of the 3,5-diarylisoxazoles reported here contain totally hydrogenated or fluorinated benzene rings on both sides of the heterocycle. Partially hydrogenated and fluorinated molecules were prepared alternating the position of the benzene rings on 3- and 5-position of the isoxazoles. Other isoxazoles were synthesized to compare the influence of fluorine atoms on the transitional properties. They were synthesized in two steps, starting from [3 + 2] 1,3-dipolar cycloaddition reaction of nitrile oxides with alkenes to yield the isoxazolines and subsequent MnO2-oxidation process to reach the final isoxazoles.
- Lopes, Luana D.,Bortoluzzi, Adailton J.,Prampolini, Giacomo,dos Santos, Francisco P.,Livotto, Paolo R.,Merlo, Aloir A.
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supporting information
p. 24 - 36
(2018/04/23)
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- TBAI-catalyzed intramolecular annulation of chalcone oximes toward isoxazoles
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A TBAI-catalyzed intramolecular annulation of chalcone oximes toward isoxazoles was developed, providing 3,5-diarylisoxazoles in good yields. Functional groups such as methoxy, ethyoxyl, chloro, bromo, fluoro and nitro were well tolerated in this reaction
- Abdukader, Ablimit,Sun, Yadong,Zhang, Zengpeng,Liu, Chenjiang
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- Synthesis of Isoxazolines and Isoxazoles via Metal-Free Desulfitative Cyclization
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A novel, one-pot reaction for the synthesis of isoxazolines and isoxazoles is developed via a cascade process under metal-free conditions. The approach involves the formation of intramolecular C-N and C-O bonds and intermolecular C-C bonds from aromatic alkenes or alkynes and N -hydroxysulfonamides using hypervalent iodine(VII) and iodine as the oxidant. Activation of C-H and C-C bonds/construction of C-O bonds/elimination of SO 2 /C-N bond formation is achieved in sequence in the reaction system.
- Cheng, Jiaxin,Yang, Ze,Li, Yuansheng,Xi, Yulan,Sun, Qiu,He, Ling
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p. 2385 - 2393
(2018/05/28)
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- Design and synthesis of a new series of 3,5-disubstituted isoxazoles active against Trypanosoma cruzi and Leishmania amazonensis
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Chagas disease and leishmaniasis are neglected tropical diseases (NTDs) endemic in developing countries. Although there are drugs available for their treatment, efforts on finding new efficacious therapies are continuous. The natural lignans grandisin (1)
- da Rosa, Rafael,de Moraes, Milene H?ehr,Zimmermann, Lara Almida,Schenkel, Eloir Paulo,Steindel, Mario,Bernardes, Lílian Sibelle Campos
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- Base-Promoted [3+2]-Annulation of Oxime Esters and Aldehydes for Rapid Isoxazoline Formation
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A base-promoted [3+2]-annulation of ketoxime esters and aldehydes is disclosed for the facile and rapid synthesis of 3,5-disubstituted and 3,4,5-trisubstituted isoxazolines. The key to our success is the pivalate leaving group of the oxime substrates, combined with cesium carbonate as promoter. This chemistry allows the assembly of a vast array of isoxazoline derivatives under simple base conditions in a method complementary to the classic isoxazoline formation via [3+2]-dipolar cycloaddition of nitrile oxides and olefins. It also represents a new reaction pattern involving electrophilic amination/N–O bond substitution. (Figure presented.).
- Huang, Huawen,Li, Feifei,Xu, Zhenhua,Cai, Jinhui,Ji, Xiaochen,Deng, Guo-Jun
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p. 3102 - 3107
(2017/09/13)
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- Synthesis of enaminones via copper-catalyzed decarboxylative coupling reaction under redox-neutral conditions
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A novel copper-catalyzed C(sp3)-H oxidative functionalization of aromatic oxime acetates with α-oxocarboxylic acids was reported. This process involved N-O/C-C bond cleavages and C-C bond formations to furnish substituted enaminones under redox-neutral conditions. The oxime acetates served as both reactants and internal oxidants. Furthermore, this transformation also features good functional group tolerance and needs no ligands or additional bases.
- Zhu, Zhongzhi,Tang, Xiaodong,Li, Jianxiao,Li, Xianwei,Wu, Wanqing,Deng, Guohua,Jiang, Huanfeng
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p. 3228 - 3231
(2017/03/20)
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- Copper-catalyzed aerobic oxidative C-O bond formation for the synthesis of 3,5-disubstituted isoxazoles from enone oximes
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A direct access to 3,5-disubstituted isoxazoles has been accomplished through an intramolecular oxidative coupling reaction of enone oximes using a catalytic quantity of Cu(OAc)2. This method features an inexpensive metal catalyst, molecular ox
- Sun, Yadong,Abdukader, Ablimit,Zhang, Haiyan,Yang, Wanle,Liu, Chenjiang
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p. 55786 - 55789
(2017/12/26)
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- Cu(I) catalyzed microwave assisted telescopic synthesis of 3,5-disubstituted isoxazoles in green media
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A facile and efficient microwave assisted telescopic synthesis of diverse isoxazoles was reported in green reaction medium. Initially, N-hydroxyl imidoyl chlorides were reacted with substituted alkynes in aqueous medium using 2 mol% of [Cu(phen)(PPh3
- Meena,Maiti, Barnali,Chanda, Kaushik
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p. 5514 - 5517
(2016/11/19)
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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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- 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 direct access to isoxazoles from ynones using trimethylsilyl azide as amino surrogate under metal/catalyst free conditions
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A general method for isoxazoles from readily available ynones using trimethylsilyl azide as an amino surrogate, likely via an unprecedented hydroazidation of the alkyne and denitrogenative cyclization, is demonstrated. The method neither required any cata
- Kumar, Gadi Ranjith,Kumar, Yalla Kiran,Reddy, Maddi Sridhar
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supporting information
p. 6589 - 6592
(2016/06/01)
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- Visible-light-mediated generation of nitrile oxides for the photoredox synthesis of isoxazolines and isoxazoles
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Visible-light photoredox catalysis enables the synthesis of biologically relevant isoxazolines and isoxazoles from hydroxyimino acids. The process shows broad functional group compatibility and mechanistic and computational studies support a visible-light-mediated generation of nitrile oxides by two sequential oxidative single electron transfer processes.
- Svejstrup, Thomas D.,Zawodny, Wojciech,Douglas, James J.,Bidgeli, Damon,Sheikh, Nadeem S.,Leonori, Daniele
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p. 12302 - 12305
(2016/10/22)
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- Copper(0) Nanoparticles in Click Chemistry: Synthesis of 3,5-Disubstituted Isoxazoles
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An efficient procedure for the synthesis of 3,5-disubstituted isoxazoles via [3+2] cycloaddition reaction of in situ generated nitrile oxides with acetylenes employing readily preparable copper(0) nanoparticles is described. A variety of in situ generated
- Vishwanatha,Sureshbabu, Vommina V.
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p. 1823 - 1833
(2015/02/19)
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- Simple and highly efficient synthesis of 3,5-disubstituted isoxazoles using Cu/graphene/clay nanohybrid as a new heterogeneous nano catalyst
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A facile and convenient protocol for 'click' cycloaddition of structurally diverse alkynes with in situ generated nitrile oxides catalysed by Cu/aminoclay/reduced graphene oxide nanohybrid (Cu/AC/r-GO nanohybrid) as a highly efficient heterogeneous nano-c
- Behrouz, Somayeh,Rad, Mohammad Navid Soltani
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p. 683 - 687
(2016/01/25)
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- Metal-free DBU promoted regioselective synthesis of isoxazoles and isoxazolines
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A new simple and efficient metal-free 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) promoted regioselective synthesis of 3,5-disubstituted isoxazoles and isoxazolines from aldoximes has been described. This method allows the reaction to proceed efficiently on aldoximes containing unprotected phenolic hydroxyl groups. Furthermore, with the use of higher equivalents of N-chlorosuccinimide, chloro-substituted isoxazoles and isoxazolines were obtained as the only products via tandem one-pot 1,3-dipolar cycloaddition followed by regioselective chlorination. This journal is
- Mohammed, Shabber,Vishwakarma, Ram A.,Bharate, Sandip B.
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p. 3470 - 3473
(2015/02/03)
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- CATALYTIC REACTION
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A catalytic reaction comprises several steps: providing a catalyst, wherein the catalyst is metal or metal oxide particles and at least have {110} crystal plane; using the catalyst when performing a cycloaddition reaction. By using the catalyst with high
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Paragraph 0033; 0037
(2015/10/05)
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- Selectfluor-Bu4NI-Mediated C(sp3)-H Oxidation in Aqueous Media: Synthesis of Δ2-Isoxazolines from Oximes
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The direct functionalization of an aliphatic C-H bond within a complex molecule through a free-radical pathway is a valuable tool in synthetic chemistry. Herein, we developed an efficient transition-metal-free approach to generate Δ2-isoxazolines from oximes by radical-mediated C(sp3)-H oxidation. Investigation of the mechanism suggested that in the presence of Selectfluor and Bu4NI, the homolysis of the in situ formed O-I bond generated an iminoxyl radical that facilitated subsequent 1,5-H transfer and C(sp3)-H oxidation. The title reaction involves Selectfluor-Bu4NI-mediated C-O bond formation in aqueous media under metal-free conditions. A variety of Δ2-isoxazolines are directly synthesized from oximes by remote intramolecular functionalization of C(sp3)-H bonds.
- Shi, Di,Qin, Hai-Tao,Zhu, Chen,Liu, Feng
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supporting information
p. 5084 - 5088
(2015/08/18)
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- Copper-doped silica cuprous sulfate (CDSCS) as a highly efficient heterogeneous nano catalyst for synthesis of 3,5-disubstituted isoxazoles
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A facile and highly efficient protocol for 1,3-dipolar cycloaddition of in situ generated nitrile oxides with terminal alkynes catalyzed by copper-doped silica cuprous sulfate (CDSCS) as a new and convenient heterogeneous nano catalyst is described. In th
- Soltani Rad,Behrouz,Faghihi
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p. 361 - 367
(2014/04/03)
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