- C-H Allylic Bond Cleavage to generate an Active Hydridopalladium Species for the Alkoxycarbonylation of Alkenes. X-Ray Crystal Structure of
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On the basis of a reactivity study using various alkenes and of the X-ray crystal structure analysis of the title compound isolated from the alkoxycarbonylation reaction, the formation of an active Pd(H)(SnCl3) species, generated from the SnCl2-PPh3 system, is proposed.
- Chenal, Thomas,Naigre, Ruth,Cipres, Isabelle,Kalck, Philippe,Daran, Jean-Claude,Vaissermann, Jacqueline
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Read Online
- Radical Reactions of N -Heterocyclic Carbene Boranes with Organic Nitriles: Cyanation of NHC-Boranes and Reductive Decyanation of Malononitriles
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The observation that NHC-boryl radicals abstract cyano groups from various organic nitriles has been parlayed into two complementary transformations. In the main group chemistry aspect, reactions of various NHC-boranes with simple organic dinitriles selectively provide stable NHC-boryl mono- or dinitriles, depending on the nitrile source. In the organic synthesis aspect, reaction of malononitriles and related derivatives with readily available 1,3-dimethylimidazol-2-ylidene borane provides reductively decyanated products in good yields.
- Kawamoto, Takuji,Geib, Steven J.,Curran, Dennis P.
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Read Online
- Boronic Acid-Mediated Photocatalysis Enables the Intramolecular Hydroacylation of Olefins Using Carboxylic Acids
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An intramolecular hydroacylation of olefins using carboxylic acids (CAs) has been developed. With the aid of a boronic acid, CAs can be used as acyl-radical precursors in catalytic photoredox reactions driven by visible light. The CAs are easily converted into their corresponding cyclic ketones without the need to use any stoichiometric activating reagents. Mechanistic studies implied that the formation of an “ate” complex from the CA and boronic acid is crucial for the generation of the acyl radical equivalent from the unreactive carboxy group.
- Nanjo, Takeshi,Takemoto, Yoshiji,Yumura, Taichi
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supporting information
(2022/03/31)
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- Green Esterification of Carboxylic Acids Promoted by tert-Butyl Nitrite
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In this work, the green esterification of carboxylic acids promoted by tert-butyl nitrite has been well developed. This transformation is compatible with a broad range of substrates and exhibits excellent functional group tolerance. Various drugs and substituted amino acids are applicable to this reaction under near neutral conditions, with good to excellent yields.
- Cheng, Xionglve,Jiang, Gangzhong,Li, Xingxing,Tao, Suyan,Wan, Xiaobing,Zhao, Yanwei,Zheng, Yonggao
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supporting information
p. 2713 - 2718
(2021/06/25)
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- Preparation method of carboxylic ester compound
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The invention relates to a preparation method of a carboxylic ester compound, which comprises the following steps: reacting carboxylic acid with methanol in air under the catalysis of nitrite to obtain an ester compound, the preparation method disclosed by the invention has the advantages of rich raw material sources, cheap and easily available catalyst, mild reaction conditions, simplicity and convenience in operation and the like, a series of fatty carboxylic acids can be modified with high yield, and particularly, the traditional esterification method is generally not suitable for esterification of drug molecules. By utilizing the method, a series of known drug molecules can be modified, so that a shortcut is provided for discovering new drug molecules.
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Paragraph 0064-0065
(2021/03/30)
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- Enantioselective C-H Amination Catalyzed by Nickel Iminyl Complexes Supported by Anionic Bisoxazoline (BOX) Ligands
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The trityl-substituted bisoxazoline (TrHBOX) was prepared as a chiral analogue to a previously reported nickel dipyrrin system capable of ring-closing amination catalysis. Ligand metalation with divalent NiI2(py)4 followed by potassium graphite reduction afforded the monovalent (TrHBOX)Ni(py) (4). Slow addition of 1.4 equiv of a benzene solution of 1-adamantylazide to 4 generated the tetrazido (TrHBOX)Ni(κ2-N4Ad2) (5) and terminal iminyl adduct (TrHBOX)Ni(NAd) (6). Investigation of 6 via single-crystal X-ray crystallography, NMR and EPR spectroscopies, and computations revealed a Ni(II)-iminyl radical formulation, similar to its dipyrrinato congener. Complex 4 exhibits enantioselective intramolecular C-H bond amination to afford N-heterocyclic products from 4-aryl-2-methyl-2-azidopentanes. Catalytic C-H amination occurs under mild conditions (5 mol % catalyst, 60 °C) and provides pyrrolidine products in decent yield (29%-87%) with moderate ee (up to 73%). Substrates with a 3,5-dialkyl substitution on the 4-aryl position maximized the observed enantioselectivity. Kinetic studies to probe the reaction mechanism were conducted using 1H and 19F NMR spectroscopies. A small, intermolecular kinetic isotope effect (1.35 ± 0.03) suggests an H-atom abstraction step with an asymmetric transition state while the reaction rate is measured to be first order in catalyst and zeroth order in substrate concentrations. Enantiospecific deuterium labeling studies show that the enantioselectivity is dictated by both the H-atom abstraction and radical recombination steps due to the comparable rate between radical rotation and C-N bond formation. Furthermore, the competing elements of the two-step reaction where H-removal from the pro-R configuration is preferred while the preferential radical capture occurs with the Si face of the carboradical likely lead to the diminished ee observed, as corroborated by theoretical calculations. Based on these enantio-determining steps, catalytic enantioselective synthesis of 2,5-bis-tertiary pyrrolidines is demonstrated with good yield (50-78%) and moderate ee (up to 79%).
- Dong, Yuyang,Lund, Colton J.,Porter, Gerard J.,Clarke, Ryan M.,Zheng, Shao-Liang,Cundari, Thomas R.,Betley, Theodore A.
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supporting information
p. 817 - 829
(2021/02/03)
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- Copper-Catalyzed Conjugate Addition of Carbonyls as Carbanion Equivalent via Hydrazones
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Copper-catalyzed conjugate addition is a classic method for forming new carbon-carbon bonds. However, copper has never showed catalytic activity for umpolung carbanions in hydrazone chemistry. Herein, we report a facile conjugate addition of hydrazone catalyzed by readily available copper complexes at room temperature. The employment of mesitylcopper(I) and electron-rich phosphine bidentate ligand is a key factor affecting reactivity. The reaction allows various aromatic hydrazones to react with diverse conjugated compounds to produce 1,4-adducts in yields of about 20 to 99%.
- Luo, Siyi,Peng, Marie,Querard, Pierre,Li, Chen-Chen,Li, Chao-Jun
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p. 13111 - 13117
(2021/09/18)
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- Nickel-Mediated Alkoxycarbonylation for Complete Carbon Isotope Replacement
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Many commercial drugs, as well as upcoming pharmaceutically active compounds in the pipeline, display aliphatic carboxylic acids or derivatives thereof as key structural entities. Synthetic methods for rapidly accessing isotopologues of such compounds are highly relevant for undertaking critical pharmacological studies. In this paper, we disclose a direct synthetic route allowing for full carbon isotope replacement via a nickel-mediated alkoxycarbonylation. Employing a nickelII pincer complex ([(N2N)Ni-Cl]) in combination with carbon-13 labeled CO, alkyl iodide, sodium methoxide, photocatalyst, and blue LED light, it was possible to generate the corresponding isotopically labeled aliphatic carboxylates in good yields. Furthermore, the developed methodology was applied to the carbon isotope substitution of several pharmaceutically active compounds, whereby complete carbon-13 labeling was successfully accomplished. It was initially proposed that the carboxylation step would proceed via the in situ formation of a nickellacarboxylate, generated by CO insertion into the Ni-alkoxide bond. However, preliminary mechanistic investigations suggest an alternative pathway involving attack of an open shell species generated from the alkyl halide to a metal ligated CO to generate an acyl NiIII species. Subsequent reductive elimination involving the alkoxide eventually leads to carboxylate formation. An excess of the alkoxide was essential for obtaining a high yield of the product. In general, the presented methodology provides a simple and convenient setup for the synthesis and carbon isotope labeling of aliphatic carboxylates, while providing new insights about the reactivity of the N2N nickel pincer complex applied.
- Ton, Stephanie J.,Neumann, Karoline T.,N?rby, Peter,Skrydstrup, Troels
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supporting information
p. 17816 - 17824
(2021/11/04)
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- Efficient C-H Amination Catalysis Using Nickel-Dipyrrin Complexes
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A dipyrrin-supported nickel catalyst (AdFL)Ni(py) (AdFL: 1,9-di(1-adamantyl)-5-perfluorophenyldipyrrin; py: pyridine) displays productive intramolecular C-H bond amination to afford N-heterocyclic products using aliphatic azide substrates. The catalytic amination conditions are mild, requiring 0.1-2 mol% catalyst loading and operational at room temperature. The scope of C-H bond substrates was explored and benzylic, tertiary, secondary, and primary C-H bonds are successfully aminated. The amination chemoselectivity was examined using substrates featuring multiple activatable C-H bonds. Uniformly, the catalyst showcases high chemoselectivity favoring C-H bonds with lower bond dissociation energy as well as a wide range of functional group tolerance (e.g., ethers, halides, thioetheres, esters, etc.). Sequential cyclization of substrates with ester groups could be achieved, providing facile preparation of an indolizidine framework commonly found in a variety of alkaloids. The amination cyclization reaction mechanism was examined employing nuclear magnetic resonance (NMR) spectroscopy to determine the reaction kinetic profile. A large, primary intermolecular kinetic isotope effect (KIE = 31.9 ± 1.0) suggests H-atom abstraction (HAA) is the rate-determining step, indicative of H-atom tunneling being operative. The reaction rate has first order dependence in the catalyst and zeroth order in substrate, consistent with the resting state of the catalyst as the corresponding nickel iminyl radical. The presence of the nickel iminyl was determined by multinuclear NMR spectroscopy observed during catalysis. The activation parameters (ΔH? = 13.4 ± 0.5 kcal/mol; ΔS?= -24.3 ± 1.7 cal/mol·K) were measured using Eyring analysis, implying a highly ordered transition state during the HAA step. The proposed mechanism of rapid iminyl formation, rate-determining HAA, and subsequent radical recombination was corroborated by intramolecular isotope labeling experiments and theoretical calculations.
- Betley, Theodore A.,Clarke, Ryan M.,Dong, Yuyang,Porter, Gerard J.
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supporting information
p. 10996 - 11005
(2020/07/08)
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- Iron-catalysed 1,2-aryl migration of tertiary azides
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1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
- Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
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supporting information
p. 11685 - 11688
(2020/10/19)
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- Palladium-Catalyzed Alkoxycarbonylation of sec-Benzylic Ethers
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Herein, we report the palladium-catalyzed synthesis of 3-arylpropionate esters starting from secondary benzylic ethers. With this investigation it could be shown that ethers are suitable starting materials in addition to the established carbonylation reactions of olefins, alcohols, or aryl halides.
- Beller, Matthias,Jackstell, Ralf,Maes, Bert U. W.,Schneider, Carolin
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supporting information
(2020/02/25)
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- Two-way homologation of aliphatic aldehydes: Both one-carbon shortening and lengthening via the same intermediate
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Aliphatic aldehydes can be homologated to both one-carbon shorter and one-carbon longer homologous carbonyl compounds through the 2–4 steps of reactions via the same intermediates, β,γ-unsaturated α-nitrosulfones, prepared from the proline-catalyzed sequential reactions of several aliphatic aldehydes with phenylsulfonylnitromethane. While the oxidative cleavage of the key intermediates gave one-carbon less homologous carbonyl compounds, the reduction of the same key intermediates followed by an oxidation produced one-carbon more homologous carbonyl compounds.
- Yoo, Jae Won,Seo, Youngran,Park, Jong Beom,Kim, Young Gyu
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- A general platinum-catalyzed alkoxycarbonylation of olefins
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Hydroxy- and alkoxycarbonylation reactions constitute important industrial processes in homogeneous catalysis. Nowadays, palladium complexes constitute state-of-the-art catalysts for these transformations. Herein, we report the first efficient platinum-catalysed alkoxycarbonylations of olefins including sterically hindered and functionalized ones. This atom-efficient catalytic transformation provides straightforward access to a variety of valuable esters in good to excellent yields and often with high selectivities. In kinetic experiments the activities of Pd- and Pt-based catalysts were compared. Even at low catalyst loading, Pt shows high catalytic activity.
- Beller, Matthias,Dühren, Ricarda,Franke, Robert,Ge, Yao,Huang, Weiheng,Jackstell, Ralf,Liu, Jiawang,Neumann, Helfried,Schneider, Carolin,Yang, Ji
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supporting information
p. 5235 - 5238
(2020/07/30)
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- Palladium catalyzed hydroesterification of substituted alkenes under microwave conditions
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While several catalyst systems have been utilized in the hydroesterification or methoxycarbonylation of alkenes or equivalent substrates, these reactions are conventionally performed in autoclave reactor systems under high CO pressure (20-70 bar) and thermal heating (70 - 110 oC). In this paper, the first methoxycarbonylation reactions performed in a microwave reactor fitted with a gas-Addition accessory system are reported on and compared to the same reactions performed under conventional heating in an autoclave reactor. Thus 1-octene, styrene, allylbenzene, o-and p-methoxyallylbenzene and β-methylstyrene were subjected to methoxycarbonylation over a palladium acetate-aluminum triflate catalyst system at 12 bar and 95 oC. Results obtained indicated the methoxycarbonylation of these alkenes to be much faster under microwave conditions when compared to conventional heating and improvements in conversion ranged between 3 and 5% for the more reactive substrates (1-octene and styrene) and 6 - 20% for the allylbenzenes and β-methylstyrene.
- Du Plessis, Maretha,Marais, Charlene,Bezuidenhoudt, Barend C. B.
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supporting information
p. 40 - 48
(2020/09/16)
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- Cobalt(II)-Catalyzed Alkoxycarbonylation of Aliphatic Amines via C-N Bond Activation
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The first cobalt-catalyzed deaminative alkoxycarbonylation reaction was described for the conversion of readily available primary alkyl amines to synthetically versatile esters with moderate to high yields. This transformation shows good functional group compatibility and can serve as a powerful tool for the modification of alkyl amine-containing complex natural products and drug molecules.
- Li, Chong-Liang,Jiang, Xuan,Lu, Liang-Qiu,Xiao, Wen-Jing,Wu, Xiao-Feng
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supporting information
p. 6919 - 6923
(2019/09/07)
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- Catalytic C-H Amination Mediated by Dipyrrin Cobalt Imidos
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Reduction of (ArL)CoIIBr (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin) with potassium graphite afforded the novel CoI synthon (ArL)CoI. Treatment of (ArL)CoI with a stoichiometric amount of various alkyl azides (N3R) furnished three-coordinate CoIII alkyl imidos (ArL)Co(NR), as confirmed by single-crystal X-ray diffraction (R: CMe2Bu, CMe2(CH2)2CHMe2). The exclusive formation of four-coordinate cobalt tetrazido complexes (ArL)Co(κ2-N4R2) was observed upon addition of excess azide, inhibiting any subsequent C-H amination. However, when a weak C-H bond is appended to the imido moiety, as in the case of (4-azido-4-methylpentyl)benzene, intramolecular C-H amination kinetically outcompetes formation of the corresponding tetrazene species to generate 2,2-dimethyl-5-phenylpyrrolidine in a catalytic fashion without requiring product sequestration. The imido (ArL)Co(NAd) exists in equilibrium in the presence of pyridine with a four-coordinate cobalt imido (ArL)Co(NAd)(py) (Ka = 8.04 M-1), as determined by 1H NMR titration experiments. Kinetic studies revealed that pyridine binding slows down the formation of the tetrazido complex by blocking azide coordination to the CoIII imido. Further, (ArL)Co(NR)(py) displays enhanced C-H amination reactivity compared to that of the pyridine-free complex, enabling higher catalytic turnover numbers under milder conditions. The mechanism of C-H amination was probed via kinetic isotope effect experiments [kH/kD = 10.2(9)] and initial rate analysis with para-substituted azides, suggesting a two-step radical pathway. Lastly, the enhanced reactivity of (ArL)Co(NR)(py) can be correlated to a higher spin-state population, resulting in a decreased crystal field due to a geometry change upon pyridine coordination.
- Baek, Yunjung,Betley, Theodore A.
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supporting information
p. 7797 - 7806
(2019/05/22)
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- Reductive C-C Coupling by Desulfurizing Gold-Catalyzed Photoreactions
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[Au2(μ-dppm)2]Cl2-mediated photocatalysis reactions are usually initiated by ultraviolet A (UVA) light; herein, an unreported system using blue light-emitting diodes (LEDs) as excitation light source was found. The red shift of the absorption wavelength originates from the combination of [Au2(μ-dppm)2]Cl2 and ligand (Ph3P or mercaptan). On the basis of this finding, a gold-catalyzed reductive desulfurizing C-C coupling of electrophilic radicals and styrenes mediated by blue LEDs is presented, a coupling which cannot be efficiently accessed by previously reported methods. This mild and highly efficient C-C bond formation strategy uses mercaptans both as electron-deficient alkyl radical precursor as well as the hydrogen source. Two examples of amino acids have also been modified by using this strategy. Moreover, this methodology could be applied in polymer synthesis. Gram-scale synthesis and mechanistic insights into this transformation are also presented.
- Zhang, Lumin,Si, Xiaojia,Yang, Yangyang,Witzel, Sina,Sekine, Kohei,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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p. 6118 - 6123
(2019/07/03)
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- Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
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The presence of different aldehydes is found to have a significant influence on the catalytic performance when using PN(H)P type ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted the observed high chemoselectivity.
- Jiang, Xiaolin,Zhang, Jiahui,Zhao, Dongmei,Li, Yuehui
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p. 2797 - 2800
(2019/03/27)
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- A Selective and Functional Group-Tolerant Ruthenium-Catalyzed Olefin Metathesis/Transfer Hydrogenation Tandem Sequence Using Formic Acid as Hydrogen Source
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A ruthenium-catalyzed transfer hydrogenation of olefins utilizing formic acid as a hydrogen donor is described. The application of commercially available alkylidene ruthenium complexes opens access to attractive C(sp3)-C(sp3) bond formation in an olefin metathesis/transfer hydrogenation sequence under tandem catalysis conditions. High chemoselectivity of the developed methodology provides a remarkable synthetic tool for the reduction of various functionalized alkenes under mild reaction conditions. The developed methodology is applied for the formal synthesis of the drugs pentoxyverine and bencyclane.
- Zieliński, Grzegorz K.,Majtczak, Jaros?awa,Gutowski, Maciej,Grela, Karol
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p. 2542 - 2553
(2018/03/09)
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- Alkoxycarbonylation of olefins with carbon dioxide by a reusable heterobimetallic ruthenium-cobalt catalytic system
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The heterobimetallic ruthenium-cobalt catalytic system exhibited good catalytic performance and reusability in the reductive alkoxycarbonylation of olefins with carbon dioxide. Compared to the previous system only consisting of ruthenium catalyst, the binary catalyst system effectively reduced the usage of noble metal and ionic liquid additives. The respective contribution of ruthenium and cobalt catalysts in this multiple-step catalytic process was investigated by a series of condition-controlled experiments. The evolution of the ruthenium catalyst and the occurrence of alkene hydrogenation during the reaction was explained by theortical calculations.
- Zhang, Xuehua,Shen, Chaoren,Xia, Chungu,Tian, Xinxin,He, Lin
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supporting information
p. 5533 - 5539
(2019/01/03)
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- Decarboxylative Negishi Coupling of Redox-Active Aliphatic Esters by Cobalt Catalysis
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A cobalt-catalyzed decarboxylative Negishi coupling reaction of redox-active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkyl–aryl, alkyl–alkenyl, and alkyl–alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (±)-preclamol highlight the synthetic potential of this method. Mechanistic studies indicated that a radical mechanism is involved.
- Liu, Xu-Ge,Zhou, Chu-Jun,Lin,Han, Xiang-Lei,Zhang, Shang-Shi,Li, Qingjiang,Wang, Honggen
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p. 13096 - 13100
(2018/09/21)
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- Development and Application of a Recyclable High-Load Magnetic Co/C Hybrid ROMP-Derived Benzenesulfonyl Chloride Reagent and Utility of Corresponding Analogues
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The development and application of high-load, recyclable magnetic Co/C hybrid ROMP-derived benzenesulfonyl chloride and analogues is reported. The regeneration and utility of these reagents in the methylation/alkylation of various carboxylic acids is demonstrated via efficient retrieval of the magnetic reagent with a neodymium magnet. Additional reactions employing the analogue sulfonic acid and in situ generated magnetic benzenesulfonyl azide are also reported.
- Faisal, Saqib,Zang, Qin,Maity, Pradip K.,Brandhofer, Agnes,Kearney, Patrick C.,Reiser, Oliver,Grass, Robert N.,Stoianova, Diana,Hanson, Paul R.
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supporting information
p. 2274 - 2277
(2017/05/12)
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- Carbonyls as Latent Alkyl Carbanions for Conjugate Additions
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Conjugate addition of carbon nucleophiles to electron-deficient olefins is one of the most powerful methods for forming carbon–carbon bonds. Despite great achievements in controlling the selectivity, variation of the carbon nucleophiles remains largely underexplored, with this approach relying mostly on organometallic reagents. Herein, we report that naturally abundant carbonyls can act as latent carbon nucleophiles for conjugate additions through a ruthenium-catalyzed process, with water and nitrogen as innocuous byproducts. The key to our success is homogeneous ruthenium(II) catalysis, combined with phosphines as spectator ligands and hydrazine as the reducing agent. This chemistry allows the incorporation of highly functionalized alkyl fragments into a vast array of electron-deficient olefins under mild reaction conditions in a reaction complementary to the classical organometallic-reagent-based conjugate additions mediated or catalyzed by “soft” transition metals.
- Dai, Xi-Jie,Wang, Haining,Li, Chao-Jun
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supporting information
p. 6302 - 6306
(2017/05/19)
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- Catalytic Hydrogenolysis of Enantioenriched Donor–Acceptor Cyclopropanes Using H2 and Palladium on Charcoal
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The hydrogenolysis of enantioenriched donor–acceptor (D–A) cyclopropanes using H2 (1 atm) and a catalytic amount of palladium on charcoal gave trans-α-alkoxycarbonyl-β-benzyl-γ-lactones or β-substituted γ-aryl-α,α-diesters with high enantiomeric excess. The reaction was also used as a key step in the asymmetric total synthesis of yatein with high ee and excellent dr. This demonstrates the utility of this new protocol for the asymmetric synthesis of trans-α,β-disubstituted γ-butyrolactones. D–A cyclopropanes containing electron-withdrawing groups at the β-position were not susceptible to hydrogenolysis under these conditions. The reductive ring-opening of a D–A cyclopropane using D2 instead of H2 generated the corresponding monodeuterated product.
- Sone, Yoshitomo,Kimura, Yumi,Ota, Ryotaro,Mochizuki, Takehito,Ito, Junki,Nishii, Yoshinori
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supporting information
p. 2842 - 2847
(2017/05/29)
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- Photoredox-Assisted Reductive Cross-Coupling: Mechanistic Insight into Catalytic Aryl-Alkyl Cross-Couplings
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Here, we describe a photoredox-assisted catalytic system for the direct reductive coupling of two carbon electrophiles. Recent advances have shown that nickel catalysts are active toward the coupling of sp3-carbon electrophiles and that well-controlled, light-driven coupling systems are possible. Our system, composed of a nickel catalyst, an iridium photosensitizer, and an amine electron donor, is capable of coupling halocarbons with high yields. Spectroscopic studies support a mechanism where under visible light irradiation the Ir photosensitizer in conjunction with triethanolamine are capable of reducing a nickel catalyst and activating the catalyst toward cross-coupling of carbon electrophiles. The synthetic methodology developed here operates at low 1 mol % catalyst and photosensitizer loadings. The catalytic system also operates without reaction additives such as inorganic salts or bases. A general and effective sp2-sp3 cross-coupling scheme has been achieved that exhibits tolerance to a wide array of functional groups.
- Paul, Avishek,Smith, Mark D.,Vannucci, Aaron K.
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p. 1996 - 2003
(2017/02/26)
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- The scope and mechanism of palladium-catalysed Markovnikov alkoxycarbonylation of alkenes
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Hydroesterification reactions represent a fundamental type of carbonylation reaction and constitute one of the most important industrial applications of homogeneous catalysis. Over the past 70 years, numerous catalyst systems have been developed that allow for highly linear-selective (anti-Markovnikov) reactions and are used in industry to produce linear carboxylates starting from olefins. In contrast, a general catalyst system for Markovnikov-selective alkoxycarbonylation of aliphatic olefins remains unknown. In this paper, we show that a specific palladium catalyst system consisting of PdX2/N-phenylpyrrole phosphine (X, halide) catalyses the alkoxycarbonylation of various alkenes to give the branched esters in high selectivity (branched selectivity up to 91%). The observed (and unexpected) selectivity has been rationalized by density functional theory computation that includes a dispersion correction.
- Li, Haoquan,Dong, Kaiwu,Jiao, Haijun,Neumann, Helfried,Jackstell, Ralf,Beller, Matthias
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p. 1159 - 1166
(2016/11/28)
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- Metal-Free Enantioselective Oxidative Arylation of Alkenes: Hypervalent-Iodine-Promoted Oxidative C?C Bond Formation
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The enantioselective oxyarylation of (E)-6-aryl-1-silyloxylhex-3-ene was achieved using a lactate-based chiral hypervalent iodine(III) reagent in the presence of boron trifluoride diethyl etherate. The silyl ether promotes the oxidative cyclization, and enhances the enantioselectivity. In addition, the corresponding aminoarylation was achieved.
- Shimogaki, Mio,Fujita, Morifumi,Sugimura, Takashi
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supporting information
p. 15797 - 15801
(2016/12/16)
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- Purification method of phenylbutyric acid
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The invention discloses a purification method of phenylbutyric acid. The purification method comprises the following steps: (1) under catalysis of a catalyst, industrial grade phenylbutyric acid reacts in an alcohol solvent, and the system after reaction is treated to obtain 4-phenylbutyrate; and (2) in presence of a basic catalyst or acidic catalyst, the 4-phenylbutyrate hydrolyzes in a solvent to obtain purified phenylbutyric acid, so that purification of the industrial grade phenylbutyric acid is realized According to the purification method disclosed by the invention, a commercially available phenylbutyric acid industrial product is taken as a raw material, firstly methyl 4-phenylbutyrate is prepared, and then high-purity phenylbutyric acid is obtained by hydrolysis and acidification to provide a raw material for obtaining high-purity sodium phenylbutyrate. The purification method takes alcohols (methanol and ethanol) as reaction solvents, and compared with synthetic methods of phenylbutyric acid in the prior art, the purification method disclosed by the invention is more environment-friendly and greener, purification of the phenylbutyric acid is realized by two steps of ordinary reaction, the purity of the purified phenylbutyric acid achieves 99.5%, and single impurity is controlled within 0.13%.
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Paragraph 0040-0049
(2017/01/17)
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- Preparation method for sodium phenylbutyrate
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The invention discloses a preparation method for sodium phenylbutyrate. The method comprises the following steps: (1) purification of 4-phenylbutyric acid: 1) under the catalysis of a catalyst, reacting industrial grade phenylbutyric acid in alcoholic solvents, and treating a reacted system to obtain the 4-phenylbutyric acid; 2) in the existence of an alkali catalyst or an acidic catalyst, performing hydrolysis reaction on the 4-phenylbutyric acid in a solvent to obtained purified phenylbutyric acid, namely, the industrial grade phenylbutyric acid is purified; (2) preparation of the sodium phenylbutyrate: enabling the phenylbutyric acid which is purified by the step 1) to react with a sodium reagent to obtain the sodium phenylbutyrate. According to the preparation method disclosed by the invention, alcohols (methyl alcohol and ethyl alcohol) serve as reaction solvents, so that the preparation method is more environmentally -friendly and green compared with a synthesis method in the prior art; the preparation of high-purity methyl alcohol is realized through a three-step conventional reaction; the purity of the sodium phenylbutyrate prepared by the preparation method reaches 99.5 percent or above, and single impurities are controlled to be within 0.1 percent.
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Paragraph 0052-0056
(2017/06/29)
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- Compounds with cardiac myosin activating function and pharmaceutical composition containing the same for treating or preventing heart failure
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The present invention relates to a compound having a cardiotonic activating function and a pharmaceutical composition containing the same. The composition comprising the compound according to the present invention is effective in preventing or treating heart failure. In addition, the compound is represented by chemical formula 2 or is pharmaceutically acceptable salt thereof.COPYRIGHT KIPO 2016
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Paragraph 1668; 1669-1671
(2017/02/02)
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- Parameters Influencing Reactivity and Regioselectivity in the Methoxycarbonylation of Arylalkenes
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Previous research showed that the steric bulk, electronic character, and bite angle of the ligand have an influence on both the catalyst activity and regioselectivity of hydroformylation and hydroesterification reactions. However, little is known in this regard about the influence of the steric and electronic environment around the double bond of the substrate. A variety of arylalkenes were therefore subjected to methoxycarbonylation to investigate the steric and electronic effects of substituents on the aromatic ring of the substrate on the regioselectivity and reactivity in the methoxycarbonylation reaction of these substrates with a Pd(II)/Al(OTf)3/Ph3P catalyst system.
- Du Plessis, Maretha,Marais, Charlene,Bezuidenhoudt, Barend C. B.
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p. 557 - 565
(2016/02/14)
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- Compounds with cardiac myosin activating function and pharmaceutical composition containing the same for treating or preventing heart failure
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Disclosed are a compound having cardiotonic activity and a pharmaceutical composition containing the same, and the composition containing the compound, according to the present invention, is useful for preventing and treating heart failure.COPYRIGHT KIPO 2016
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Paragraph 1669-1671
(2016/10/07)
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- A recyclable CO surrogate in regioselective alkoxycarbonylation of alkenes: Indirect use of carbon dioxide
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Herein, we report a Pd-catalysed alkoxycarbonylation of alkenes based on the use of a recyclable CO2 reduction product, the crystalline and air-stable N-formylsaccharin, as a CO surrogate. The carbonylation proceeds under ambient conditions in an exceptionally complementary regioselective fashion yielding the desired branched products from styrene derivatives and valuable linear esters from alkyl-substituted alkenes.
- Gehrtz,Hirschbeck,Fleischer
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supporting information
p. 12574 - 12577
(2015/08/06)
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- Sunlight-driven trifluoromethylation of olefinic substrates by photoredox catalysis: A green organic process
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The principles and utility of photoredox catalysis in organic synthesis are described. After a brief description of the features of the two types of catalytic photoredox processes following the reductive quenching cycle (RQC) and the oxidative quenching cycle (OQC), the discussion is focused on organic transformations based on OQC, in particular the trifluoromethylation of olefinic substrates with electrophilic trifluoromethylating reagents furnishing solvolytic addition products and substitution products. It is concluded that catalytic photoredox systems are green from the point of view of harmfulness, safety, and energy source (visible light, including sunlight). Future prospects of photoredox catalysis will be also discussed.
- Akita, Munetaka,Koike, Takashi
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p. 742 - 751
(2015/07/15)
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- METHOD FOR PRODUCING ORGANIC COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of subjecting a compound having on one carbon atom a carbon atom constituting a carbon-carbon double bond and a functional group such as a hydroxyl group to a reductive reaction condition and producing an organic compound having the functional group substituted with a hydrogen atom. SOLUTION: There is provided a method for producing a compound represented by a formula (50) from a raw material compound represented by a formula (10). The method includes a step of irradiating a reaction system with light, the reaction system comprising the raw material compound, a hydrogen source compound, and a catalyst having a palladium component supported by a carrier containing titanium oxide. (R11 to R15 are a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms which may have a cyclic structure or a derivative group thereof, or a heteroatom-containing group having 1 to 20 carbon atoms which may have a cyclic structure or a derivative group thereof; and R16 is a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms or an acyl group having 1 to 20 carbon atoms which may have a cyclic structure, or -CH(CH2OH)2).) COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0084-0087; 0097; 0129; 0132; 0138
(2018/10/16)
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- AZOLE HETEROCYCLIC COMPOUND, PREPARATION METHOD, PHARMACEUTICAL COMPOSITION AND USE
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The present invention relates to the filed of pharmarcutical chemistry, and in particular, to a novel class of azole compounds represented by general formula (I), (II) or (III) amd a preparation method thereof, a pharmarcutical composition with the compounds as active components, and a use of the azole compounds and the pharmarcutical composition in the preparation of a medicament for treatment of diseases associated with Lp-PLA2 enzyme activities, wherein each substituent is as deinfed in the specifictaion.
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Paragraph 0323; 0324
(2014/05/20)
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- AZOLE HETEROCYCLIC COMPOUND, PREPARATION METHOD, PHARMACEUTICAL COMPOSITION AND USE
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The present invention relates to the field of pharmaceutical chemistry, and in particular, to a novel class of azole compounds represented by general formula (I), (II) or (III) and a preparation method thereof, a pharmaceutical composition with the compounds as active components, and a use of the azole compounds and the pharmaceutical composition in the preparation of a medicament for treatment of diseases associated with Lp-PLA2 enzyme activities, wherein each substituent is as defined in the specification.
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Paragraph 0674; 0675
(2014/06/25)
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- Mechanism of SmI2/amine/H2O-promoted chemoselective reductions of carboxylic acid derivatives (esters, acids, and amides) to alcohols
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Samarium(II) iodide-water-amine reagents have emerged as some of the most powerful reagents (E° = -2.8 V) for the reduction of unactivated carboxylic acid derivatives to primary alcohols under single electron transfer conditions, a transformation that had been considered to lie outside the scope of the classic SmI2 reductant for more than 30 years. In this article, we present a detailed mechanistic investigation of the reduction of unactivated esters, carboxylic acids, and amides using SmI2-water-amine reagents, in which we compare the reactivity of three functional groups. The mechanism has been studied using the following: (i) kinetic, (ii) reactivity, (iii) radical clock, and (iv) isotopic labeling experiments. The kinetic data indicate that for the three functional groups all reaction components (SmI2, amine, water) are involved in the rate equation and that the rate of electron transfer is facilitated by base assisted deprotonation of water. Notably, the mechanistic details presented herein indicate that complexation between SmI2, water, and amines can result in a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to a variety of carboxylic acid derivatives. These observations will have important implications for the design and optimization of new processes involving Sm(II)-reduction of ketyl radicals. (Chemical Equation Presented).
- Szostak, Michal,Spain, Malcolm,Eberhart, Andrew J.,Procter, David J.
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p. 11988 - 12003
(2015/01/16)
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- On the role of pre- and post-electron-transfer steps in the SmI 2/Amine/H2O-mediated reduction of esters: New mechanistic insights and kinetic studies
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The mechanism of the SmI2-mediated reduction of unactivated esters has been studied using a combination of kinetic, radical clocks and reactivity experiments. The kinetic data indicate that all reaction components (SmI2, amine, H2O) are involved in the rate equation and that electron transfer is facilitated by Bronsted base assisted deprotonation of water in the transition state. The use of validated cyclopropyl-containing radical clocks demonstrates that the reaction occurs via fast, reversible first electron transfer, and that the electron transfer from simple Sm(II) complexes to aliphatic esters is rapid. Notably, the mechanistic details presented herein indicate that complexation between SmI2, H2O and amines affords a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to carboxylic acid derivatives as an attractive alternative to the classical hydride-mediated reductions and as a source of acyl-radical equivalents for C-C bond forming processes. Electron donors: The mechanism of the SmI 2-mediated reduction of unactivated esters has been studied by using a combination of kinetic, radical clock, and reactivity experiments. Notably, the mechanistic details presented herein indicate that complexation between SmI2, H2O, and amines gives a new class of structurally diverse, thermodynamically powerful reductants for efficient electron transfer to carboxylic acid derivatives as an attractive alternative to the classical hydride-mediated reductions and as a source of acyl-radical equivalents for C-C bond-forming processes (see scheme).
- Szostak, Michal,Spain, Malcolm,Procter, David J.
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supporting information
p. 4222 - 4226
(2014/05/06)
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- A resin-linker-vector approach to radiopharmaceuticals containing 18F: Application in the synthesis of O-(2-[18F]- Fluoroethyl)-L-tyrosine
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A Resin-linker-vector (RLV) strategy is described for the radiosynthesis of tracer molecules containing the radionuclide 18F, which releases the labelled vector into solution upon nucleophilic substitution of a polystyrene-bound arylsulfonate linker with [18F]-fluoride ion. Three model linker-vector molecules 7 a-c containing different alkyl spacer groups were assembled in solution from (4-chlorosulfonylphenyl)alkanoate esters, exploiting a lipase-catalysed chemoselective carboxylic ester hydrolysis in the presence of the sulfonate ester as a key step. The linker-vector systems were attached to aminomethyl polystyrene resin through amide bond formation to give RLVs 8 a-c with acetate, butyrate and hexanoate spacers, which were characterised by using magic-angle spinning (MAS) NMR spectroscopy. On fluoridolysis, the RLVs 8 a, b containing the longer spacers were shown to be more effective in the release of the fluorinated model vector (4-fluorobutyl)phenylcarbamic acid tert-butyl ester (9) in NMR kinetic studies and gave superior radiochemical yields (RCY≈60 %) of the 18F- labelled vector. The approach was applied to the synthesis of the radiopharmaceutical O-(2-[18F]-fluoroethyl)-L-tyrosine ([ 18F]-FET), delivering protected [18F]-FET in >90 % RCY. Acid deprotection gave [18F]-FET in an overall RCY of 41 % from the RLV. Copyright
- Topley, Amy C.,Isoni, Valerio,Logothetis, Thomas A.,Wynn, Duncan,Wadsworth, Harry,Gibson, Alex M. R.,Khan, Imtiaz,Wells, Neil J.,Perrio, Cécile,Brown, Richard C.D.
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supporting information
p. 1720 - 1725
(2013/02/25)
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- Esterification catalysis by pyridinium p -toluenesulfonate revisited - Modification with a lipid chain for improved activities and selectivities
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The lipid analogs of pyridinium p-toluenesulfonate (PPTS) were examined for catalysis of the condensation of an equimolar mixture of carboxylic acids and alcohols under mild conditions without removal of water. Although PPTS is a poor catalyst, the introduction of a lipid chain and nitro group significantly improved the activity of PPTS and led to selectivity at suppressing the elimination side reactions of alcohols. 2-Oleamido-5-nitro-pyridinium p-toluenesulfonate (6) is a lead catalyst that promoted various esterification reactions with yields up to 99%.
- Wang, Wei,Liu, Huimin,Xu, Shaoyi,Gao, Yong
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p. 2906 - 2912
(2013/09/02)
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- N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate as a highly active and selective esterification catalyst
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N-Butyl-2,4-dinitro-anilinium p-toluenesulfonate (1) was found to be a very active esterification catalyst that promotes condensation of equal mole amount of carboxylic acids and alcohols under mild conditions. This catalyst is also highly selective towards carboxylic acid and alcohol substrates at ambient temperature.
- Sattenapally, Narsimha,Wang, Wei,Liu, Huimin,Gao, Yong
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supporting information
p. 6665 - 6668
(2013/11/19)
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- Rhodium-catalyzed oxygenative addition to terminal alkynes for the synthesis of esters, amides, and carboxylic acids
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A gem of a couple: The title reaction of terminal alkynes with O and Nnucleophiles proceeds in the presence of [Rh(cod)Cl}2], P(4-FC 6H4)3, and 4-picoline N-oxide. Alcohols, amines, and water add to the terminal alkynes to give esters, amides, and carboxylic acids, respectively. The reaction involves formation of a rhodium vinylidene, oxidation to a ketene by oxygen transfer, and nucleophilic addition.
- Kim, Insu,Lee, Chulbom
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supporting information
p. 10023 - 10026
(2013/10/01)
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- Imidazolium-salt-functionalized ionic-CNT-supported Ru-carbene/palladium nanoparticles for recyclable tandem metathesis/hydrogenation reactions in ionic liquids
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NP and tuck: Two different catalysts, a Ru-carbene complex and palladium nanoparticles, were immobilized onto the same imidazolium-salt-functionalized ionic CNTs. These supported dual-function catalysts showed excellent catalytic activity in tandem metathesis/hydrogenation reactions in an ionic liquid and could be recovered and reused four times. RCM=ring-closing metathesis. Copyright
- Lee, Sujin,Shin, Ju Yeon,Lee, Sang-Gi
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supporting information
p. 1990 - 1993
(2013/09/23)
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- Total synthesis of (+)-trans-trikentrin A
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Several syntheses have already been reported for cis-trikentrins and herbindoles, which are indole alkaloids unsubstituted at the C2 and C3 positions that bear a trans-1,3-dimethylcyclopentyl unit. Herein, we describe the first asymmetric and stereoselective synthesis of the more challenging trans-trikentrin A as its naturally occurring isomer. Different approaches were investigated and the strategy of choice was a combination of an enzymatic kinetic resolution and a thallium(III)-mediated ring contraction. The antiproliferative activities of the natural product and related intermediates have been tested against human tumor cell lines, leading to the discovery of new compounds with potent antitumor activity. Simple target? Take a look again! The first stereoselective synthesis of a trans-trikentrin is described (see scheme). In contrast, all cis-related natural products have already been synthesized. An enzymatic kinetic resolution and a ring contraction are the key steps. Potent antitumor compounds have been discovered during this study. Copyright
- Tébéka, Iris R. M.,Longato, Giovanna B.,Craveiro, Marcus V.,De Carvalho, Jo?o E.,Ruiz, Ana L. T. G.,Silva Jr., Luiz F.
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p. 16890 - 16901
(2013/03/14)
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- Effective oxidation of benzylic and alkane C-H bonds catalyzed by sodium o-iodobenzenesulfonate with Oxone as a terminal oxidant under phase-transfer conditions
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Catalytic oxidation of benzylic C-H bonds could be efficiently realized using IBS as a catalyst which was generated in situ from the oxidation of sodium 2-iodobenzenesulfonate (1b) by Oxone in the presence of a phase-transfer catalyst, tetra-n-butylammonium hydrogen sulfate, in anhydrous acetonitrile at 60 °C. Various alkylbenzenes, including toluenes and ethylbenzenes, several oxygen-containing functionalities substituted alkylbenzenes, and a cyclic benzyl ether could be efficiently oxidized. And, the same reagent system of cat. 1b/Oxone/cat. n-Bu4NHSO4 could be applied to the effective oxidation of alkanes as well.
- Cui, Li-Qian,Liu, Kai,Zhang, Chi
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supporting information; experimental part
p. 2258 - 2265
(2011/05/08)
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- Short-chain HDAC inhibitors differentially affect vertebrate development and neuronal chromatin
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Carboxylic acids with known central nervous system and histone deacetylase (HDAC) inhibitory activities were converted to hydroxamic acids and tested using a suite of in vitro biochemical assays with recombinant HDAC isoforms, cell based assays in human cervical carcinoma HeLa cells and primary cultures from mouse forebrain, and a whole animal (Xenopus laevis) developmental assay. Relative to the parent carboxylic acids, two of these analogues exhibited enhanced potency, and one analogue showed altered HDAC isoform selectivity and in vivo activity in the Xenopus assay. We discuss potential uses of these novel hydroxamic acids in studies aimed at determining the utility of HDAC inhibitors as memory enhancers and mood stabilizers.
- Fass, Daniel M.,Shah, Rishita,Ghosh, Balaram,Hennig, Krista,Norton, Stephanie,Zhao, Wen-Ning,Reis, Surya A.,Klein, Peter S.,Mazitschek, Ralph,Maglathlin, Rebecca L.,Lewis, Timothy A.,Haggarty, Stephen J.
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scheme or table
p. 39 - 42
(2011/04/17)
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- CARBOXYLIC DERIVATIVES FOR USE IN THE TREATMENT OF CANCER
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The invention provides novel compounds of formula (I), wherein: R1 is a radical derived from one of the known ring systems; R2 is a phenyl radical optionally substituted; Xn represents a birradical selected from the group consisting of: -(CH2)1-4-, (C2-C4)-alkenyl, (C2-C4)alkynyl, -S-(CH2)1-3-#, and -(CH2)1-3-O-#; wherein the symbol # indicates the position at which Xn is attached to R1; Yn is a birradical selected from the group consisting of: -(CH2)2-4-, -S-(CH2)1-3#, and -O-(CH2)1-3-#,; where in the symbol # indicates the position at which Yn is attached to R2; and R3 is a radical selected from the group consisting of: -OR4. The compounds of formula (I) are useful in the treatment of cancer
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Page/Page column 24
(2009/07/25)
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- CALCILYTIC COMPOUNDS
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Novel calcilytic compounds, pharmaceutical compositions, methods of synthesis and methods of using them are provided.
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Page/Page column 22
(2008/12/06)
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