- Magnetic chitosan-functionalized cobalt-NHC: Synthesis, characterization and catalytic activity toward Suzuki and Sonogashira cross-coupling reactions of aryl chlorides
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Aryl chlorides are one of the most stable and available electrophiles, however, their coupling with nucleophiles remains a challenge in organic synthesis. Herein, we prepared a Cobalt-NHC (N-Heterocyclic carbene) complex anchored on magnetic chitosan nanoparticles and assayed its catalytic activity for the reactions of substituted phenylboronic acid and also phenlacetylene with derivatives of aryl chlorides. These reactions are of great importance since they are employed for the synthesis of unsymmetrical diarylethynes and biphenyls, which belong to a prime class of building blocks. The synthesized nanocatalyst was found to be highly efficient in Suzuki and Sonogashira coupling in terms of their activity and recyclability in polyethylene glycol (PEG) as a green reaction media under conditions of temperatures (70 and 100 °C) and Co loading (3 and 6 mol%). To the best of our knowledge, this is the first attempt of using cobalt-NHC complex for catalyzing the abovementioned reactions. Moreover, replacing the earth-abundant Cobalt-based catalyst as an alternative to high cost palladium make this approach promising from sustainable chemistry view.
- Hajipour, Abdol R.,Malek, Shaghayegh Sadeghi
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- Palladium-Catalyzed Electrophilic Functionalization of Pyridine Derivatives through Phosphonium Salts
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Herein, we report a highly efficient and practical method for pyridine-derived heterobiaryl synthesis through palladium-catalyzed electrophilic functionalization of easily available pyridine-derived quaternary phosphonium salts. The nice generality of this reaction was goes beyond arylation, enabling facile incorporation of diverse carbon-based fragments, including alkenyl, alkynyl, and also allyl fragments, onto the pyridine core. Notably, the silver salt additive is revealed to be of vital importance for the success of this transformation and its pivotal role as transmetallation mediator, which guarantees a smooth transfer of pyridyl group to palladium intermediate, is also described.
- Che, Yuan-Yuan,Deng, Xuezu,Feng, Chao,Lin, Ling-Zhi,Pei, Bingbing,Yue, Yanni
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supporting information
p. 16414 - 16419
(2020/07/20)
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- Biaryl Cross-Coupling Enabled by Photo-Induced Electron Transfer
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We report a protocol for aryl cross-coupling of electron-deficient aryl halides with electron-rich (hetero)arenes that is driven solely by violet light. This process takes advantage of formation of photo-excited state of electron-deficient aryl halides, that are reduced by electron-rich (hetero)arenes to form a pair of aryl anion and cation radicals. The resulting aryl anion radicals of aryl halides undergo mesolysis of the carbon-halogen bond to generate aryl radicals, that are coupled most likely with aryl cation radicals to afford functionalized biaryls. (Figure presented.).
- Hayashi, Hirohito,Wang, Bin,Wu, Xiangyang,Teo, Shi Jie,Kaga, Atsushi,Watanabe, Kohei,Takita, Ryo,Yeow, Edwin K. L.,Chiba, Shunsuke
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supporting information
p. 2223 - 2231
(2020/04/30)
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- Novel Insights into the Combination of Metal- and Biocatalysis: Cascade One-Pot Synthesis of Enantiomerically Pure Biaryl Alcohols in Deep Eutectic Solvents
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One of the pioneering examples of chemoenzymatic cascades in water such as the palladium-catalysed Suzuki-cross coupling followed by an enzymatic reduction has been revisited by the employment of a medium containing Deep Eutectic Solvents (DESs) for the catalytic performance. Thus, the unique properties of these neoteric solvents enabled to reach high substrate concentration for the overall process. Moreover, both isolated enzymes and whole cells exhibited excellent activities which allowed to obtain a set of chiral biaryl alcohols in good yields and very high enantiomeric excess (>99 %).
- Paris, Juraj,Ríos-Lombardía, Nicolás,Morís, Francisco,Gr?ger, Harald,González-Sabín, Javier
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p. 4417 - 4423
(2018/09/14)
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- Development of a Unique Heterogeneous Palladium Catalyst for the Suzuki–Miyaura Reaction using (Hetero)aryl Chlorides and Chemoselective Hydrogenation
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A unique heterogeneous palladium catalyst (7% Pd/WA30) supported on an anion exchange resin, which contains N,N-dimethylaminoalkyl functionalities on the polymer backbone, was developed. 7% Pd/WA30 could smoothly catalyze Suzuki–Miyaura reactions of even less reactive heteroaryl chlorides and heteroarylboronic acids to afford various (hetero)biaryls due to the electron-donating effect of the tert-amines on WA30 to Pd species. It was also applicable as a chemoselective hydrogenation catalyst, showing inactivity for the hydrogenolysis of tert-butyldimethylsilyl (TBS) ethers, alkyl benzyl ethers, and benzyl alcohols. The tert-amines on WA30 acted as moderate catalyst poisons for Pd, resulting in chemoselective hydrogenation. 7% Pd/WA30 was reused for at least five times without any loss of the hydrogenation catalytic activity. (Figure presented.).
- Ichikawa, Tomohiro,Netsu, Moeko,Mizuno, Masahiro,Mizusaki, Tomoteru,Takagi, Yukio,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 2269 - 2279
(2017/07/07)
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- One-dimensional chiral Cu (II) chain complex and its preparation method and use
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The invention discloses a one-dimensional chiral Cu (II) chain complex and a preparation method thereof. The preparation method comprises firstly synthesizing a chiral organic ligand L, then synthesizing a chiral Cu (II) molecular building unit through co
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Paragraph 0052
(2017/05/11)
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- Palladium-catalyzed decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides
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Decarboxylative cross-coupling of 3-pyridyl and 4-pyridyl carboxylates with aryl bromides is reported. Using a bimetallic system of Cu2O and Pd(PPh3)4, the scope of the reaction is demonstrated by the synthesis of 27 pyridine-containing biaryls in moderate to good yields.
- Chennamaneni, Lohitha Rao,William, Anthony D.,Johannes, Charles W.
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p. 1293 - 1296
(2015/03/04)
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- SYSTEM FOR CONTROLLING THE REACTIVITY OF BORONIC ACIDS
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A protected organoboronic acid includes a boron having an sp3 hybridization, a conformationally rigid protecting group bonded to the boron, and an organic group bonded to the boron through a boron-carbon bond. A method of performing a chemical reaction includes contacting a protected organoboronic acid with a reagent, the protected organoboronic acid including a boron having an sp3 hybridization, a conformationally rigid protecting group bonded to the boron, and an organic group bonded to the boron through a boron-carbon bond. The organic group is chemically transformed, and the boron is not chemically transformed.
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Page/Page column 23
(2009/02/11)
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- Microwave-assisted Suzuki coupling reactions with an encapsulated palladium catalyst for batch and continuous-flow transformations
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This article describes the design, optimisation and development of a Suzuki cross-coupling protocol mediated by an efficient palladium-en-capsulated catalyst (Pd EnCat) under microwave irradiation. The methodology has been used in both batch mode for classical library preparation and in continuous-flow applications furnishing multigram quantities of material. Described is a method that uses direct focused microwave heating whilst applying an external cooling source. This enables a lower than normal bulk temperature to be maintained throughout the reaction period leading to significant improvements in the overall yield and purity of the reaction products. Additional aspects of this novel heating protocol are discussed in relation to the prolonged lifetime and enhanced reactivity of the immobilised catalyst system.
- Baxendale, Ian R.,Griffiths-Jones, Charlotte M.,Ley, Steven V.,Tranmer, Geoffrey K.
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p. 4407 - 4416
(2008/02/07)
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- Nitrogenous tetrahydropyridyl-alkyl-heterocycles with tnf activity
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This invention relates to nitrogenous (tetrahydropyridyl)(alkyl)heterocycles, to pharmaceutical compositions comprising them, to processes for preparing them and to the method of use thereof in the treatment of pain and diseases related to immune and inflammatory disorders.
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- Synthesis of functionalized 4-phenyl-pyridines via electrochemically prepared organozinc reagents
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The efficient and convenient synthesis of various functionalized 4-phenyl-pyridines 2 is described. The key step of the procedure is the electrochemical formation of aromatic organozinc reagents 1 and their coupling with pyridinium salts. Intermediate 1,4
- Gall, Erwan Le,Gosmini, Corinne,Nédélec, Jean-Yves,Périchon, Jacques
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p. 1923 - 1927
(2007/10/03)
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- Novel 1-(Pyridylphenyl)-1-phenyl-2-imidazolylethanols with Topical Antiinflammatory Activity
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The synthesis, biological evaluation, and structure-activity relationshios of a series of 1-(pyridylphenyl)-1-phenyl-2-imidazolylethanols are described.These compounds show potent dose-dependent topical antiinflammatory activity in murine models of skin i
- Wright, Stephen W.,Harris, Richard R.,Collins, Robert J.,Corbett, Ronald L.,Green, Alicia M.,et al.
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p. 3148 - 3155
(2007/10/02)
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