- Continuous Flow Synthesis of Azoxybenzenes by Reductive Dimerization of Nitrosobenzenes with Gel-Bound Catalysts
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In the search for a new synthetic pathway for azoxybenzenes with different substitution patterns, an approach using a microfluidic reactor with gel-bound proline organocatalysts under continuous flow is presented. Herein the formation of differently substituted azoxybezenes by reductive dimerization of nitrosobenzenes within minutes at mild conditions in good to almost quantitative yields is described. The conversion within the microfluidic reactor is analyzed and used for optimizing and validating different parameters. The effects of the different functionalities on conversion, yield, and reaction times are analyzed in detail by NMR. The applicability of this reductive dimerization is demonstrated for a wide range of differently substituted nitrosobenzenes. The effects of these different functionalities on the structure of the obtained azoxyarenes are analyzed in detail by NMR and single-crystal X-ray diffraction. Based on these results, the turnover number and the turnover frequency were determined.
- Schmiegel, Carsten J.,Berg, Patrik,Obst, Franziska,Schoch, Roland,Appelhans, Dietmar,Kuckling, Dirk
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p. 1628 - 1636
(2021/03/15)
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- Azobioisosteres of Curcumin with Pronounced Activity against Amyloid Aggregation, Intracellular Oxidative Stress, and Neuroinflammation
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Many (poly-)phenolic natural products, for example, curcumin and taxifolin, have been studied for their activity against specific hallmarks of neurodegeneration, such as amyloid-β 42 (Aβ42) aggregation and neuroinflammation. Due to their drawbacks, arising from poor pharmacokinetics, rapid metabolism, and even instability in aqueous medium, the biological activity of azobenzene compounds carrying a pharmacophoric catechol group, which have been designed as bioisoteres of curcumin has been examined. Molecular simulations reveal the ability of these compounds to form a hydrophobic cluster with Aβ42, which adopts different folds, affecting the propensity to populate fibril-like conformations. Furthermore, the curcumin bioisosteres exceeded the parent compound in activity against Aβ42 aggregation inhibition, glutamate-induced intracellular oxidative stress in HT22 cells, and neuroinflammation in microglial BV-2 cells. The most active compound prevented apoptosis of HT22 cells at a concentration of 2.5 μm (83 % cell survival), whereas curcumin only showed very low protection at 10 μm (21 % cell survival).
- Hofmann, Julian,Ginex, Tiziana,Espargaró, Alba,Scheiner, Matthias,Gunesch, Sandra,Aragó, Marc,Stigloher, Christian,Sabaté, Raimon,Luque, F. Javier,Decker, Michael
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p. 6015 - 6027
(2021/03/16)
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- Azo aryl urea derivative, and preparation method and application thereof
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The invention relates to an azo aryl urea derivative, and a preparation and an application thereof, and concretely discloses a compound represented by formula (I), or an optical isomer, a cis-trans-isomer or a pharmaceutically acceptable salt thereof, and a preparation method thereof. Definitions of substituent groups in the general formula are described in the specification and claims. The invention further discloses a composition containing the above compound, and an application thereof. The compound has excellent anticancer activity on HepG2 liver cancer cells, MGC803 gastric cancer cells,HCT116 colon cancer and the like.
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Paragraph 0077-0078; 0079-0080; 0137-0140; 0193-0196
(2020/06/17)
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- Enantioselective Oxidative Coupling of β-Ketocarbonyls and Anilines by Joint Chiral Primary Amine and Selenium Catalysis
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An enantioselective primary amine-catalyzed total N-selective nitroso aldol reaction (N-NA) was achieved through the oxidation of primary aromatic amines to the corresponding nitrosoarenes catalyzed by selenium reagents and 30% H2O2. This protocol provides a facile and highly efficient access to α-hydroxyamino carbonyls bearing chiral quaternary centers under exceedingly mild and green reaction conditions with high chemo-and enantiocontrol.
- Chen, Wanting,Wang, Yanni,Mi, Xueling,Luo, Sanzhong
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supporting information
p. 8178 - 8182
(2019/10/16)
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- Azobenzene-benzoylphenylureas as photoswitchable chitin synthesis inhibitors
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Benzoylphenylureas (BPUs) are used as synthetic insect growth regulators for inhibiting chitin synthesis. Merging insecticidal BPUs with photoswitchable azobenzene generated photoresponsive chitin synthesis inhibitors. A prepared azobenzene-benzoylphenylurea can be activated upon irradiation with UV light, and shows 6-fold and 2-fold activity difference to armyworm (Mythimna separata) and German cockroach (Blattella germanica) sulfonylurea receptors, respectively. This is the first example of a photoswitchable BPU insecticide. The generation of such a photoresponsive BPU insecticide allows for modulation of the insecticidal activity by light, and may facilitate the spatiotemporal control over the sulfonylurea receptor and the mechanistic study of this kind of insecticide.
- Tian, Xue,Zhang, Chao,Xu, Qi,Li, Zhong,Shao, Xusheng
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p. 3320 - 3323
(2017/04/21)
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- Photoswitchable thioureas for the external manipulation of catalytic activity
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A series of azobenzene-based thiourea catalysts have been developed with the aim of achieving control over the catalytic activity by the use of light. The conceptual design of these systems relies on the inactivation by means of intramolecular hydrogen bonding, only likely to take place in one of their isomeric forms. After fine structure modulation of the catalyst a substantial difference in activity has been observed between the irradiated and the nonirradiated reaction. Furthermore, the system allowed in situ manipulation of the catalyst activity during the course of a given experiment.
- Osorio-Planes, Laura,Rodriguez-Escrich, Carles,Pericas, Miquel A.
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supporting information
p. 1704 - 1707
(2014/04/17)
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- Design and synthesis of a photoswitchable guanidine catalyst
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A novel design as well as a straight-forward synthesis for a photoswitchable guanidine catalyst is reported. Intense studies of the photochromic properties demonstrated the reversible switchability of its photosensitive azobenzene moiety. Its activity in
- Viehmann, Philipp,Hecht, Stefan
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p. 1825 - 1830,6
(2020/09/16)
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- N-Arylhydroxamic acids as novel oxidoreductase substrates
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N-Arylhydroxamic acids (AHAs) are promising novel N-OH mediators for oxidoreductase catalysis. They are electrochemically active compounds with a redox potential of 0.31-0.41 V vs. SCE. Representative oxidoreductases, e.g. fungal peroxidase from Coprinus
- Kulys, Juozas,Deussen, Heinz-Josef,Krikstopaitis, Kastis,Lolck, Rikke,Schneider, Palle,Ziemys, Arturas
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p. 3475 - 3484
(2007/10/03)
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- Nonlinear Hammett relationships in the reaction of peroxomonosulfate anion (HOOSO-3) with meta-and para-substituted anilines in alkaline medium
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The HOOSO-3 oxidation of eleven meta-and para-substituted anilines to the corresponding nitrosobenzenes at pH ≈ 11 was characterized by the rate equation v = kK[OX][An]/(1 + K[An]). Formation constant of the reactive intermediate and its rate of decomposition were evaluated separately for ascertaining the structure-reactivity relationships. Under the experimental conditions the dianion, -O-O-SO-3 is probably the effective electrophile. Kinetic data can be rationalized by a bimolecular process which involves the attack of nucleophilic nitrogen atom on the peroxidic oxygen. The highlight of the study is the opposite curvatures observed in the nonlinear Hammett plots of first-order rate constant k and the "equilibrium" constant K, being concave downward and upward, respectively.
- Meenakshisundaram, Subbiah,Sockalingam, Ramanathan
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p. 897 - 911
(2007/10/03)
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- Kinetic study of the catalytic oxidation of anilines with hydrogen peroxide
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Kinetic study of homogeneous catalytic oxidation of substituted anilines with hydrogen peroxide in the presence of H3PW12O40 showed that the reaction involves formation of intermediate substrate-oxidant complex whose decomposition determines the rate of the process. Donor substituents in the benzene ring favor the oxidation process, indicating its electrophilic nature.
- Belyaev,Mel'nikov,Zadov,Suboch
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p. 1003 - 1006
(2007/10/03)
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- Oxidation of Primary Aromatic Amines, Catalyzed by Tungsten Compounds
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Treatment of o-nitroanilines and o-aminobenzoic acids with 30 percent hydrogen peroxide in the presence of Na2WO4 and H3PO4 results in selective formation of corresponding nitroso derivatives.In other cases, the products are azoxy compounds.Oxidation of anilines containing alkyl or alkoxy groups in the ortho and para positions with hydrogen peroxide in the presence of Na2WO4 and tetrabutylammonium bromide quantitatively yields corresponding nitrosobenzenes.The H2O2-Na2WO4-H3PO4 system in the presence of tetrabutylammonium bromide is proposed for preparation of nitroso derivatives from anilines containing electron-acceptor meta and para substituents.
- Mel'nikov, E. B.,Suboch, G. A.,Belyaev, E. Yu.
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p. 1640 - 1642
(2007/10/03)
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- Photochemistry of 3- and 4-Nitrophenyl Azides: Detection and Characterization of Reactive Intermediates
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Irradiation of nitro-substituted aromatic azides initiates a complex series of chemical reactions that lead to different products depending on the details of the experiment.There is evidence that four reactive intermediates participate in product-determining reactions.These are the singlet nitrene, the triplet nitrene, the triplet azide, and the ring-expanded dehydroazepine.The chemical and physical properties of each of these species is modified by the nitro substituent.The reactivity of the singlet nitrene with nucleophilic amines is increased, the lifetime of the dehydroazepine is shortened, and the triplet nitrene becomes a powerful single-electron acceptor.Nitro-substituted aromatic azides are widely used in photolabeling experiments.The findings of this study suggest that they may be inappropriate choices as photolabeling agents in many circumstances.
- Liang, Tsuei-Yun,Schuster, Gary B.
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p. 7803 - 7810
(2007/10/02)
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- Selective weed control with m-dinitrobenzene
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Weeds can be controlled by the application as a herbicide of m-dinitrobenzene. This compound is particularly effective for selectively controlling weeds in agronomic crops.
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