- Encapsulating Cobalt into N-Doping Hollow Frameworks for Efficient Cascade Catalysis
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The development of nonprecious catalysts for hydrogenation of organic molecules is of great importance in heterogeneous catalysis. Herein, we report a series of N-doped hollow carbon frameworks encompassing cobalt nanoparticles (denoted as Co@NHF-900) constructed as a new kind of reusable catalyst for this purpose by pyrolysis of ZIF-8@Co-dopamine under Ar atmospheres. Notably, the framework of ZIF-8 is essential for efficient catalyst by providing a carbon framework to support Co-dopamine. The experimental results reveal that the ZIF-8 renders a large hollow place within the catalysts, allowing the enrichment of the substrate and windows of the hollow structure and the ease of mass transfer of products during the reaction. All of the virtues made Co@NHF-900 a good candidate for hydrogenation of quinolines with high activity (TOF value of 119 h-1, which is several times than that of akin catalysts) and chemoselectivity.
- Yun, Ruirui,Zhang, Beibei,Qiu, Chuang,Ma, Ziwei,Zhan, Feiyang,Sheng, Tian,Zheng, Baishu
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- Nanolayered Cobalt-Molybdenum Sulfides as Highly Chemo- and Regioselective Catalysts for the Hydrogenation of Quinoline Derivatives
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Herein, a general protocol for the preparation of a broad range of valuable N-heterocyclic products by hydrogenation of quinolines and related N-heteroarenes is described. Interestingly, the catalytic hydrogenation of the N-heteroarene ring is chemoselectively performed when other facile reducible functional groups, including alkenes, ketones, cyanides, carboxylic acids, esters, and amides, are present. The key to successful catalysis relies on the use of a nanolayered cobalt-molybdenum sulfide catalyst hydrothermally synthesized from earth-abundant metal precursors. This heterogeneous system displays a tunable composition of phases that allows for catalyst regeneration. Its catalytic activity depends on the composition of the mixed phase of cobalt sulfides, being higher with the presence of Co3S4, and could also be associated with the presence of transient Co-Mo-S structures that mainly vanish after the first catalytic run.
- Sorribes, Iván,Liu, Lichen,Doménech-Carbó, Antonio,Corma, Avelino
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- Cu Nanoclusters Anchored on the Metal-Organic Framework for the Hydrolysis of Ammonia Borane and the Reduction of Quinolines
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Free-access active sites created and the interaction regulated between them and substrates during the heterogeneous catalysis process are crucial, which remain a great challenge. In this work, in suit reduced to afford naked Cu nanoparticles (NPs) have been anchored on the metal-organic framework (MOF), NH2-MOF, to form Cu-NH2-MOF. The strategy can precisely control the Cu NP formation with small size and uniform distribution. The Cu NP properties and MOF advantages have been integrated to create a great catalyst with multiple functions and have resulted in improving the recyclability and superb catalytic activity for the one-pot reduction of heterocycle reactions under mild conditions. The experimental and theoretical calculation results show that the superior performance should be attributed to the framework of NH2-MOF that provides large caves for substrate enrichment and the stabilization of Cu sites by the -NH2 group.
- Yun, Ruirui,Zhang, Beibei,Zhan, Feiyang,Du, Liting,Wang, Zhaoxu,Zheng, Baishu
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supporting information
p. 12906 - 12911
(2021/08/30)
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- Synthesis of N-Alkyl Anilines from Arenes via Iron-Promoted Aromatic C-H Amination
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We report both an intermolecular C-H amination of arenes to access N-methylanilines and an intramolecular variant for the synthesis of tetrahydroquinolines. A newly developed, highly electrophilic aminating reagent was key for the direct synthesis of unprotected N-methylanilines from simple arenes. The reactions display a broad functional group tolerance and employ catalytic amounts of a benign iron salt under mild reaction conditions.
- Falk, Eric,Gasser, Valentina C. M.,Morandi, Bill
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supporting information
p. 1422 - 1426
(2021/03/08)
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- Structure-guided rescaffolding of selective antagonists of BCL-X L
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Because of the promise of BCL-2 antagonists in combating chronic lymphocytic leukemia (CLL) and non-Hodgkin's lymphoma (NHL), interest in additional selective antagonists of antiapoptotic proteins has grown. Beginning with a series of selective, potent BC
- Koehler, Michael F. T.,Bergeron, Philippe,Choo, Edna F.,Lau, Kevin,Ndubaku, Chudi,Dudley, Danette,Gibbons, Paul,Sleebs, Brad E.,Rye, Carl S.,Nikolakopoulos, George,Bui, Chinh,Kulasegaram, Sanji,Kersten, Wilhelmus J. A.,Smith, Brian J.,Czabotar, Peter E.,Colman, Peter M.,Huang, David C. S.,Baell, Jonathan B.,Watson, Keith G.,Hasvold, Lisa,Tao, Zhi-Fu,Wang, Le,Souers, Andrew J.,Elmore, Steven W.,Flygare, John A.,Fairbrother, Wayne J.,Lessene, Guillaume
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supporting information
p. 662 - 667
(2014/07/07)
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- A versatile route to red-emitting carbopyronine dyes for optical microscopy and nanoscopy
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Biological microscopy favors photostable fluorescent markers with large fluorescence quantum yields, low dark triplet state population, good biocompatibility and absorption and emission maxima in the near-infrared, where cellular autofluorescence is minimized. In the present study, carbopyronines absorbing around 640 nm and emitting at around 660 nm, with a low intersystem crossing rate (kisc ≈ 0.5×106 s-1) and excellent properties for cellular imaging were synthesized. A general synthetic route to carbopyronines with functional groups variable in the final steps of the synthesis or in the resulting fluorescent dye is presented. Possessing two 2-me-thoxyethyl groups, the parent dye is soluble in water and most organic solvents. Demethylation of the dye or its precursors is straightforward, clean, and furnishes compounds with one or two 2-hydroxyethyl groups, which can be used for further transformations. Modifications in the linker-containing carboxy group are also possible. A multistep synthesis of the dye starting from a simple precursor and utilizing a single temporary protective group is described. The presented approach may be further applied to the design of caged carbopyronines.
- Kolmakov, Kirill,Belov, Vladimir N.,Wurm, Christian A.,Harke, Benjamin,Leutenegger, Marcel,Eggeling, Christian,Hell, Stefan W.
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experimental part
p. 3593 - 3610
(2010/11/18)
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- Design and synthesis of a metabolically stable and potent antitussive agent, a novel δ opioid receptor antagonist, TRK-851
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We have previously reported on antitussive effect of (5R,9R,13S,14S)-17-cyclopropylmethyl-6,7-didehydro-4,5-epoxy-5′,6′-dihydro-3-methoxy-4′H-pyrrolo[3,2,1-ij]quinolino[2′,1′:6,7]morphinan-14-ol(1b) methanesulfonate (TRK-850), a selective δ opioid receptor antagonist which markedly reduced the number of coughs in a rat cough model. We designed TRK-850 based on naltrindole (NTI), a typical δ opioid receptor antagonist, to improve its permeability through the blood-brain barrier by introducing hydrophobic moieties to NTI. The ED50 values of NTI and compound 1b by intraperitoneal injections were 104 μg/kg and 2.07 μg/kg, respectively. This increased antitussive potency probably resulted from the improved brain exposure of compound 1b. However, 1b was extremely unstable toward metabolism by cytochrome P450. In this study, we designed and synthesized compound 1b derivatives to improve the metabolic instability, which resulted in affording highly potent and metabolically stable oral antitussive agent (5R,9R,13S,14S)-17-cyclopropylmethyl-6,7-didehydro-4,5-epoxy-8′-fluoro-5′,6′-dihydro-4′H-pyrrolo[3,2,1-ij]quinolino[2′,1′:6,7]morphinan-3,14-diol (1c) methanesulfonate (TRK-851).
- Sakami, Satoshi,Kawai, Koji,Maeda, Masayuki,Aoki, Takumi,Fujii, Hideaki,Ohno, Hiroshi,Ito, Tsuyoshi,Saitoh, Akiyoshi,Nakao, Kaoru,Izumimoto, Naoki,Matsuura, Hirotoshi,Endo, Takashi,Ueno, Shinya,Natsume, Kazuto,Nagase, Hiroshi
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p. 7956 - 7967
(2008/12/23)
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