- Steric effects of substituents of quinones on the oxygenation of ethylbenzene catalyzed by NHPI/quinone and the catalytic oxidation of ascorbate
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The substituents of quinones play an important role in modulating the kinetics of the electron- and proton-transfer reaction. In this paper, the steric effects of substituents of quinones on their catalytic performance were studied in the oxidation of ethylbenzene and ascorbate. The substituents limited the addition of the free radicals to the C=C double bonds of the quinone ring because of the steric hindrance. On the other hand, too many substituents hindered the contact between the active site (C=O) of quinone and the reactant. So, the quinones with two substituents presented better catalytic performance than those with more or less substituents. These results will be helpful in designing the quinone compounds for drugs and in understanding the catalytic behavior of quinones in biochemistry.
- Yang, Xiaomei,Wang, Ying,Zhang, Chaofeng,Fang, Tao,Zhou, Lipeng,Zhang, Wei,Xu, Jie
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- Development of new and efficient polymer-supported hypervalent iodine reagents
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The aminomethylpolystyrene-supported (diacetoxyiodo)benzene reagents 4a and 4b were prepared for the first time. Using these reagents several hydroquinones and phenols can be oxidized to the corresponding quinones. Spirocyclization of phenylacetic acid and of N-protected tyrosine derivatives could also be accomplished.
- Ficht, Simon,Mülbaier, Marcel,Giannis, Athanassios
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- Correlation between carbon-carbon bond length and the ease of retro Diels-Alder reaction
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The bond length between C8-C9 in (1′ R,4′ S,4a′ R,8a′ S)-6′,7′-dimethyl-1′,4′,4a′,8a′-tetrahydrospiro [cyclopropane-1,9′-[1,4]methanonaphthalene]-5′,8′-dione is 1.571 (2) ? and between C7-C12 is 1.567 (2) ? which are longer than the corresponding bond length for saturated bicyclic systems (1.531-1.535 ?). This paper reports the correlation between bond length and the ease of retro Diels -Alder reaction.
- Kotha, Sambasivarao,Banerjee, Shaibal,Shaikh, Mobin
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- Design, synthesis, and rearrangement studies of gem-dimethyl containing cage systems
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A variety of functionalized cage compounds and D3-trishomocubane derivatives have been assembled via the Diels–Alder strategy, with reductive cleavage of the cyclopropane ring and metal promoted ring rearrangement as key steps. We have installed the gem-dimethyl moiety on the norbornane ring system containing a cage framework by a late-stage synthetic manipulation involving the hydrogenolysis of the cyclopropane ring with the aid of Adams’ catalyst (PtO2). Several cage molecules containing methyl substituents were synthesized by starting with inexpensive and commercially available materials such as 2,3-dimethylhydroquinone, Zn/AcOH, and endo-dicyclopentadiene. These cage pentacycloundecane frameworks assembled here are difficult to synthesize by conventional routes. Some of these gem-dimethyl cage systems and D3-trishomocubane derivative was firmly supported on the basis of single-crystal X-ray diffraction studies.
- Kotha, Sambasivarao,Cheekatla, Subba Rao
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- A relationship between amide hydrogen bond strength and quinone reduction potential: Implications for photosystem I and bacterial reaction center quinone function
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A series of 11 simple phylloquinone derivatives, each lacking the extended phytyl side chain but featuring H-bond donor amides at one or both peri positions, were prepared and some salient physical properties were measured. A correlation between both IR frequency and NMR peak position, as indicators of internal H-bond strength, and the quinone half-wave reduction potential, was observed. These data are consistent with the prevailing hypothesis that quinone carbonyl H-bonding in general, and stronger H-bonds in particular, favorably bias the endogenous quinone's electrochemical potential toward easier reduction.
- Feldman, Ken S.,Hester II, D. Keith,Golbeck, John H.
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- Neuroprotection in the MPTP parkinsonian C57BL/6 mouse model by a compound isolated from tobacco
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Epidemiological evidence suggests a lower incidence of Parkinson's disease in smokers than in nonsmokers. This evidence, together with the lower levels of brain monoamine oxidase (MAO) activity in smokers and the potential neuroprotective properties of MAO inhibitors, prompted studies which led to the isolation and characterization of 2,3,6-trimethyl-1,4-naphthoquinone (TMN), an MAO-A and MAO-B inhibitor which is present in tobacco and tobacco smoke. Results of experiments reported here provide evidence that this compound protects against the MPTP-mediated depletion of neostriatal dopamine levels in the C57BL/6 mouse. These results support the hypothesis that the inhibition of MAO by constituents of tobacco smoke may be related to the decreased incidence of Parkinson's disease in smokers.
- Castagnoli, Kay P.,Steyn, Stefanus J.,Petzer, Jacobus P.,Van Der Schyf, Cornelis J.,Castagnoli Jr., Neal
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- Structural Study of the Methylnaphthazarins. X-Ray Structure of the Tetramethylnaphthazarin, a Charge Transfer Complex
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The synthesis and analysis by 1H NMR of the methyl substituted naphthazarins were attempted.The chemical shifts of the substituents and of the ring protons were compared with those in their diacetates and were then correlated with the quinonoid or benzenoid nature of the rings.X-Ray diffraction analysis of tetramethylnaphthazarin, 2,3,6,7-tetramethyl-5,8-dihydroxy-1,4-naphthoquinone, has shown that this exists, in solid state, as a centrosymmetric charge-transfer complex with itself.The compound crystallizes in the Ibam space group, with an orthorombic cell of dimensions a=17.479(1), b=9.983(1), c=6.752(1) Angstroem, and four molecules in the unit cell.The crystal is built from molecules stacked up the c-axis and the interplanar distance between two overlapping molecules is 3.38 Angstroem.
- Rodriguez, Jose-Gonzalo,Pablo, Alfonso De,Smith-Verdier, Pilar
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- Aerobic Oxidation of Dihydroxyarenes Substrates Catalyzed by Polymer-Supported RuII-Pheox/Silica-Gel: A Beneficial Route for Purification of Industrial Water
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A broad class of dihydroxyarenes were easily oxidized by aerobic oxygen to quinone products in excellent yields under the catalytic effect of polymer-supported RuII-Pheox/silica-gel catalyst. By using this combined catalyst, hydroquinone and catechol derivatives with electron-donating groups were easily oxidized by molecular oxygen to quinone products in 90% to >99% yield, while in the case of electron-withdrawing group, only 70% was obtained. The biologically useful 1,4-Naphthoqinone products were obtained in 83% to 90%. The catalyst was easily obtained and reused many times without a significant decrease in reactivity. Interestingly, a sample of industrial water contaminated with phenolic compounds was subjected to aerobic oxidation by using this catalyst, and the resultant quinones were detected within one day and the catalyst was removed and reused several times with different contami-nating samples with the same efficiency. Other catalytic oxidations by using this promising catalyst were investigated.
- Abu-Elfotoh, Abdel-Moneim
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supporting information
p. 236 - 243
(2022/04/09)
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- Pseudocyclic bis-N-heterocycle-stabilized iodanes - synthesis, characterization and applications
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Bis-N-heterocycle-stabilized λ3-iodanes (BNHIs) based on azoles are introduced as novel structural motifs in hypervalent iodine chemistry. A performance test in a variety of benchmark reactions including sulfoxidations and phenol dearomatizations revealed a bis-N-bound pyrazole substituted BNHI as the most reactive derivative. Its solid-state structure was characterizedviaX-ray analysis implying strong intramolecular interactions between the pyrazole nitrogen atoms and the hypervalent iodine centre.
- Boelke, Andreas,Lork, Enno,Nachtsheim, Boris J.,Sadat, Soleicha
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supporting information
p. 7434 - 7437
(2021/08/03)
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- Plastoquinone analogs: a potential antimicrobial lead structure intensely suppressing Staphylococcus epidermidis and Candida albicans growth
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The aim of this study was to evaluate the antimicrobial activity of twenty-five Plastoquinone analogs synthesized previously in a panel of seven bacterial strains (three Gram-positive and four Gram-negative bacteria) and three fungi. PQ1, which does not contain any substituent(s) on the phenyl ring, was the most potent compound against Staphylococcus epidermidis (8-fold more potent than Cefuroxime, MIC = 1.22 μg/mL). The antifungal profile of all Plastoquinone analogs indicated that three analogs (PQ1, PQ2, and PQ7) displayed the best antifungal activity against Candida albicans, which was about the same activity with the reference standard (MIC = 4.88 μg/mL). The structure-activity relationship study was also carried out to reveal important chemical features. After probing twenty-five Plastoquinone analogs for a potential antimicrobial lead structure, two analogs (PQ1 and PQ25) were selected for further investigation for biofilm evaluation. Based on the tests performed, there was a significant positive correlation between inhibition of the biofilm attachment and time. The results showed that both analogs (PQ1 and PQ25) are able to reduce biofilm mass. Finally, these findings endorse us further efforts to optimize two phenotypes of the Plastoquinone analogs (PQ1 and PQ25) to develop potential antimicrobial drug candidates. [Figure not available: see fulltext.]
- Ataman, Merve,Ozbek-Celik, Berna,Bayrak, Nilüfer,Matarac?-Kara, Emel,Tuyun, Ama? Fatih,Y?ld?r?m, Hatice,Y?ld?z, Mahmut
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p. 1728 - 1737
(2021/08/06)
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- Strategies towards potent trypanocidal drugs: Application of Rh-catalyzed [2?+?2?+?2] cycloadditions, sulfonyl phthalide annulation and nitroalkene reactions for the synthesis of substituted quinones and their evaluation against Trypanosoma cruzi
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Rhodium-catalyzed [2 + 2 + 2] cycloadditions, sulfonyl phthalide annulations and nitroalkene reactions have been employed for the synthesis of 56 quinone-based compounds. These were evaluated against Trypanosoma cruzi, the parasite that causes Chagas disease. The reactions described here are part of a program that aims to utilize modern, versatile and efficient synthetic methods for the one or two step preparation of trypanocidal compounds. We have identified 9 compounds with potent activity against the parasite; 3 of these were 30-fold more potent than benznidazole (Bz), a drug used for the treatment of Chagas disease. This article provides a comprehensive outline of reactions involving over 120 compounds aimed at the discovery of new quinone-based frameworks with activity against T. cruzi.
- Wood, James M.,Satam, Nishikant S.,Almeida, Renata G.,Cristani, Vinicius S.,de Lima, Dênis P.,Dantas-Pereira, Luiza,Salom?o, Kelly,Menna-Barreto, Rubem F.S.,Namboothiri, Irishi N.N.,Bower, John F.,da Silva Júnior, Eufranio N.
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- Tailoring Dihydroxyphthalazines to Enable Their Stable and Efficient Use in the Catholyte of Aqueous Redox Flow Batteries
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To enable cost-efficient stationary energy storage, organic active materials are the subject of current investigations with regard to their application in aqueous redox flow batteries. Especially quinones with their beneficial electrochemical properties and natural abundance pose a promising class of compounds for this challenging endeavor. Yet, there are not many active materials available for the catholyte side to realize solely quinone-based systems. Herein we introduce the novel hydroquinone 5,8-dihydroxy-2,3-phthalazine together with two of its derivatives and propose it as a promising active material for the catholyte side of aqueous redox flow batteries. We systematically investigate the electrochemical properties as well as the structure-property relationship of this class of compounds. The unmodified dihydroxyphthalazine exhibits a favorably high redox potential of 796 mV vs SHE in acidic solution that is competitive with benzoquinone compounds. Moreover, the introduced dihydroxyphthalazines feature a high electron transfer rate surpassing benzoquinone species by almost one order of magnitude. With regard to stable cycling performance, we further achieved a high resilience against detrimental side reactions such as Michael addition by adding methyl substituents to the base structure. Our experimental findings are supported and extended by theoretical considerations in terms of density functional theory calculations. With this combined approach we outline further promising dihydroxyphthalazine-based materials with regard to performance-relevant quantities like redox potential, cycling stability, and water solubility. This study aims to propel further research in the field of quinone-based active materials for the catholyte of future aqueous redox flow batteries.
- Hofmann, Jonas D.,Hong, Longcheng,Janek, Jürgen,Mollenhauer, Doreen,Schmalisch, Sebastian,Schr?der, Daniel,Schwan, Sebastian,Wegner, Hermann A.
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p. 3427 - 3438
(2021/06/14)
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- A new skeletal rearrangement of 1,7-dimethyl Cookson's cage dione catalyzed by a Lewis acid
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A methyl-substituted polycyclic cage dione containing the PCUD framework has undergone an unprecedented ring rearrangement approach. Here, the PCUD framework with the aid of a Lewis acid such as BF3·MeOH gave unusual fragmentation products. Two new products were isolated via the skeletal rearrangement process involving carbocation mediated intermediates. The substituents in the succinyl bond present in the strained PCUD skeleton produce a driving force for the rearrangement in an unprecedented manner. Interestingly, the cyclobutane ring was transformed to cyclopentane through the cleavage of the C1-C7 bond during the ring-expansion process of PCUD via the carbocation intermediates. Unexpectedly, solvent (benzene) was captured during the ring-homologation process due to the presence of methyl substituents placed at the cyclobutane ring of the cage framework. It appears that this is the first report where an unexpected ring-rearrangement, ring-homologation, and ring-fragmentation occur with the aid of the BF3·MeOH complex.
- Cheekatla, Subba Rao,Kotha, Sambasivarao
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p. 1377 - 1383
(2020/03/03)
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- Brominated plastoquinone analogs: Synthesis, structural characterization, and biological evaluation
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A series of brominated PQ analogs (BrPQ1-13) was synthesized by employing two different routes: 1) dibromination followed by oxidation and amination of dimethyl hydroquinone, respectively, 2) oxidation of dimethyl hydroquinone followed by amination and bromination, respectively. In addition to the single-crystal X-ray structural characterization of two analogs (BrPQ2 and BrPQ3), the structures of all analogs were determined based on spectral (FTIR, 1H NMR, 13C NMR, and HRMS) data. We evaluated the analogs for in vitro antibacterial and antifungal activity against ATCC strains (panel of seven bacterial strains with three Gram-positive and four Gram-negative bacteria and three fungi) using the broth microdilution method. The structure–activity relationship of brominated PQ analogs indicated that the electron-withdrawing group (EWG) on the phenyl ring (-CF3, trifluoromethyl group) has a positive effect on antibacterial activity. These in vitro data show that brominated analogs, especially for BrPQ 1, BrPQ2, and BrPQ3, have the potential to be developed as new antibacterial agents against S. aureus and/or S. epidermidis with low MIC values.
- Bayrak, Nilüfer,Matarac? Kara, Emel,Ozbek Celik, Berna,Tuyun, Ama? Fatih,Y?ld?r?m, Hatice,Y?ld?z, Mahmut
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- Oxidation of Electron-Rich Arenes Using HFIP-UHP System
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The straightforward oxidation of electron-rich arenes, namely, phenols, naphthols, and anisole derivatives, under mild reaction conditions, is described by means of the use of an environmentally benign HFIP-UHP system. The corresponding quinones or hydroxylated arenes were obtained in moderate to good yields.
- Llopis, Natalia,Baeza, Alejandro
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p. 6159 - 6164
(2020/05/20)
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- Synthesis method of target antioxidant SKQ1 intermediate 2,3-dimethyl-p-benzoquinone
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The invention provides a synthesis method of a target antioxidant SKQ1 intermediate 2,3-dimethyl-p-benzoquinone. The synthesis method comprises the following steps: 1) dissolving 2,3-dibromo-5,6-dimethyl-p-benzoquinone in glacial acetic acid, adding reduced iron powder, stirring at room temperature for 1 h, and carrying out a heating reflux reaction for 5 h; 2) cooling and filtering the obtained reaction mixture, evaporating the solvent in the obtained filtrate under a reduced pressure, recycling the recovered glacial acetic acid, dissolving the obtained crude product in ethanol, regulating the pH value to 9 by using a 5% aqueous sodium hydroxide solution, introducing an air flow until the mixture becomes dark blue, and monitoring the reaction completion with TLC; and 3) acidifying the reaction mixture with 10% HCl until the pH value is 4, evaporating under reduced pressure to remove most of ethanol, extracting with ethyl acetate for three times, mixing the obtained organic phases, spin-drying to remove the solvent in order to obtain an oily crude product, recovering ethyl acetate, and purifying the obtained crude product with a silica gel rapid column to obtain a faint yellow oilyproduct. The intermediate 2,3-dimethyl-p-benzoquinone of the mitochondrial antioxidant SKQ-1 is synthesized; the solvent can be recycled, so that the production cost is saved; and a raw material basis is provided for industrial synthesis of the mitochondrial antioxidant SKQ1.
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Paragraph 0015; 0023-0028
(2020/05/02)
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- Activated Carbon-Promoted Dehydrogenation of Hydroquinones to Benzoquinones, Naphthoquinones, and Anthraquinones under Molecular Oxygen Atmosphere
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We found that the activated carbon-molecular oxygen system promotes the conversion of hydroquinones to benzoquinones, naphthoquinones, and anthraquinones, which are often found in natural products and pharmaceuticals. In particular, the one-pot synthesis of naphthoquinones and anthraquinones involving a Diels-Alder reaction is a useful protocol for this purpose.
- Kim, Sanghun,Matsubara, Ryosuke,Hayashi, Masahiko
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p. 2997 - 3003
(2019/03/08)
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- Design, synthesis, and biological activity of Plastoquinone analogs as a new class of anticancer agents
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In this paper, based on Plastoquinone (PQ) analogs possessing substituted aniline containing alkoxy group(s), new 2,3-dimethyl-5-amino-1,4-benzoquinones (PQ1-15) were designed and synthesized in either two steps or one-pot reaction. Specifically, the substituted amino moiety containing mono or poly alkoxy group(s) with various positions and groups were mainly explored to understand the structure-activity relationships for the cytotoxic activity against three human cancer cell lines (K562, Jurkat, and MT-2) and human peripheral blood mononuclear cells (PBMC). PQ2 was found to be most effective anticancer compound on K562 and Jurkat cell lines with IC50 values of 6.40 ± 1.73 μM and 7.72 ± 1.49 μM, respectively. Interestingly, the compound was non-cytotoxic to normal PBMC and also MT-2 cancer cells. PQ2 which showed significant selectivity in MTT assay was chosen for apoptotic/necrotic evaluation and results exhibited that it induced apoptosis in K562 cell line after 6 h of treatment. PQ2 showed anti-Abelson kinase 1 (Abl1) activity with different inhibitory profile than Imatinib in the panel of eight kinases. The binding mode of PQ2 into Abl ATP binding pocket was predicted in silico showing the formation of some key interactions. In addition, PQ2 induced Bcr-Abl1 mediated ERK pathway in human chronic myelogenous leukemia (CML) cells. Furthermore, DNA-cleaving capability of PQ2 was clearly enhanced by iron (II) complex system. Afterward, a further in silico ADMET prediction revealed that PQ2 possesses desirable drug-like properties and favorable safety profile. These results indicated that PQ2 has multiple mechanism of action and two of them are anti-Bcr-Abl1 and DNA-cleaving activity. This study suggests that Plastoquinone analogs could be potential candidates for multi-target anticancer therapy.
- Bayrak, Nilüfer,Y?ld?r?m, Hatice,Y?ld?z, Mahmut,Radwan, Mohamed O.,Otsuka, Masami,Fujita, Mikako,Tuyun, Ama? Fatih,Ciftci, Halil I.
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- Discovery and structure–activity relationship of plastoquinone analogs as anticancer agents against chronic myelogenous leukemia cells
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Two series of amino-1,4-benzoquinones (AQ1–18) based on the structural analogs of plastoquinones were synthesized and the structure–activity relationship against chronic myelogenous leukemia activity was examined. All of the synthesized compounds were tested for their cytotoxic effects on different leukemic cell lines. Of interest, AQ15 exhibited a better selectivity than the reference drug imatinib on cancer cells. Owing to this, AQ15 was selected for a further apoptosis/necrosis evaluation where AQ15-treated K562 cells demonstrated similar apoptotic effects like imatinib-treated cells at their IC50 values. The inhibitory effects of AQ15 and the other three compounds with various activities against eight tyrosine kinases, including ABL1, were investigated. AQ15 showed weak activity against ABL1, and a correlation was observed between the anti-K562 and anti-ABL1 activities. The binding mode of AQ15 into the ATP binding pocket of ABL1 kinase was predicted in silico, showing the formation of some key interactions. In addition, AQ15 was shown to suppress the downstream signaling of BCR-ABL in K562 cells. Finally, AQ15 obviously cleaved DNA in the presence of an iron(II) complex system, indicating that this can be the major mechanism of its antiproliferative action, whereas the mild inhibition of ABL kinase is just in-part mechanism of its overall outstanding cellular activity.
- Ciftci, Halil I.,Bayrak, Nilüfer,Y?ld?r?m, Hatice,Y?ld?z, Mahmut,Radwan, Mohamed O.,Otsuka, Masami,Fujita, Mikako,Tuyun, Ama? F.
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- Synthesis method of intermediate-2,3-dimethyl-p-benzoquinone of mitochondrion targeting antioxidant SKQ1
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The invention provides a synthesis method of an intermediate-2,3-dimethyl-p-benzoquinone of a mitochondrion targeting antioxidant SKQ1. The synthesis method comprises the following steps: (1) dissolving 2,3-dimethyl phenol into dichloromethane, adding silica gel while stirring, adding pyridinium dichromate at 0 DEG C, stirring for reacting at room temperature, and displaying that the reaction is completed through TLC (Thin-Layer Chromatography); (2) adding the silica gel in a reaction solution, and evaporating a reaction solvent until completely drying the silica gel, wherein the fluidity is good; (3) paving the silica gel in a Buchner funnel with the cushion of filter paper, paving powder prepared in step (2) on the upper layer, putting the Buchner funnel on a suction flask, opening and vacuumizing, flushing the silica gel by using petroleum ether until no outflow of products, and drying the solvent through evaporation, thus obtaining a desired product, wherein the solvent can be repeatedly reutilized. According to the synthesis method provided by the invention, the use of a hazardous chemical product-concentrated sulfuric acid is avoided, and reaction conditions are mild; the solvent can be repeatedly reutilized, and the production cost is saved; no heavy metal wastewater is generated, and greening and environment protection are realized; basis is provided for industralization of the intermediate-2,3-dimethyl-p-benzoquinone of the mitochondrion targeting antioxidant SKQ1.
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Paragraph 0021-0025
(2019/02/04)
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- Iron-Catalyzed Radical Methylation of Activated Alkenes with tert -Butanol as the Methyl Source
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A free-radical-initiated methylation/addition/cyclization of N -arylacrylamides and a methylation/addition/elimination of quinines have been developed in which t -BuOH is used as a methyl source. These reactions provide effective and selective methods for the synthesis of various methylated oxindoles and quinones in moderate to good yields.
- Cao, Shouhao,Ji, Hongfang,Jia, Rui,Ma, Zhiwei,Shen, Liang,Xu, Zhengbao
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supporting information
p. 1909 - 1913
(2019/09/30)
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- Catalytic way of transforming 2,3-dimethylphenol to para-quinone with the use of vanadium-containing heteropoly acids
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2,3-Dimethyl-p-benzoquinone (2,3-Me2BQ) is a valuable chemical that is applied as a soft oxidizing and dehydrogenating agent and also as a synthon in preparing different complex products including pharmaceutical and biochemical substances. Keggin- and modified-type aqueous solutions of Mo-V-phosphoric heteropoly acids (Mo-V-P HPAs) with the gross compositions H3+xPMo12-xVxO40 (HPA-x) and HaPzMoyVx’Ob (HPA-x’), respectively, possessing high oxidation potential and simplicity of regeneration can serve as effective soft oxidants for obtaining such para-quinone from 2,3-dimethylphenol (2,3-Me2P). The synthesized HPA catalysts with different vanadium content were characterized by a number of analysis techniques, such as 31P and 51V NMR spectroscopy, potentiometry, titrimetry, and pH measurement. It was found that the predominant formation of 2,3-Me2BQ instead of corresponding diphenoquinone (DPQ) at one-electron oxidation is achieved by a consecutive optimization of reaction conditions, the most important among them being organic solvent and molar ratio of vanadium(V) to substrate. As was shown, the substitution of HPA-x by HPA-x’ allows one to increase the quinone selectivity and to decrease the optimal molar ratio of vanadium(V) to substrate. The highest yield of the desired quinone (97%) at total substrate conversion was obtained by using the biphasic water-benzene system at molar vanadium(V) to substrate ratio of 12. The temperature of 50 °C and an inert atmosphere were established to be the optimal reaction conditions. The aqueous HPA-10′ solution including the highest content of VO2+ ions proved to be the most efficient catalyst among investigated HPAs. Carrying out catalyst regeneration at a separate stage provides the preservation of its activity and selectivity at the initial level for at least ten cycles.
- Rodikova, Yulia A.,Zhizhina, Elena G.,Pai, Zinaida P.
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p. 216 - 224
(2017/10/18)
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- Catalytic Electrophilic Alkylation of p-Quinones through a Redox Chain Reaction
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Allylation and benzylation of p-quinones was achieved through an unusual redox chain reaction. Mechanistic studies suggest that the existence of trace hydroquinone initiates a redox chain reaction that consists of a Lewis acid catalyzed Friedel–Crafts alkylation and a subsequent redox equilibrium that regenerates hydroquinone. The electrophiles could be various allylic and benzylic esters. The addition of Hantzsch ester as an initiator improves the efficiency of the reaction.
- Xu, Xiao-Long,Li, Zhi
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supporting information
p. 8196 - 8200
(2017/06/30)
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- FLOUROALKYL, FLOUROALKOXY, PHENOXY, HETEROARYLOXY, ALKOXY, AND AMINE 1,4-BENZOQUINONE DERIVATIVES FOR TREATMENT OF OXIDATIVE STRESS DISORDERS
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Disclosed herein are compounds and methods of using such compounds for treating or suppressing oxidative stress disorders, including mitochondrial disorders, impaired energy processing disorders, neurodegenerative diseases and diseases of aging, or for modulating one or more energy biomarkers, normalizing one or more energy biomarkers, or enhancing one or more energy biomarkers, wherein the compounds are tocopherol quinone derivatives. Further disclosed are compounds, compositions, and methods for treatment of, or prophylaxis against, radiation exposure.
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Paragraph 0179; 0180
(2017/07/14)
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- Rhodium-catalyzed C-H bond activation for the synthesis of quinonoid compounds: Significant Anti-Trypanosoma cruzi activities and electrochemical studies of functionalized quinones
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Thirty four halogen and selenium-containing quinones, synthesized by rhodium-catalyzed C-H bond activation and palladium-catalyzed cross-coupling reactions, were evaluated against bloodstream trypomastigotes of T.?cruzi. We have identified fifteen compounds with IC50/24?h values of less than 2?μM. Electrochemical studies on A-ring functionalized naphthoquinones were also performed aiming to correlate redox properties with trypanocidal activity. For instance, (E)-5-styryl-1,4-naphthoquinone 59 and 5,8-diiodo-1,4-naphthoquinone 3, which are around fifty fold more active than the standard drug benznidazole, are potential derivatives for further investigation. These compounds represent powerful new agents useful in Chagas disease therapy.
- Jardim, Guilherme A.M.,Silva, Thaissa L.,Goulart, Marilia O.F.,de Simone, Carlos A.,Barbosa, Juliana M.C.,Salom?o, Kelly,de Castro, Solange L.,Bower, John F.,da Silva Júnior, Eufranio N.
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supporting information
p. 406 - 419
(2017/05/19)
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- Controlled radical polymerization of alkyl acrylates in the presence of the tri-n-butylborane–p-quinone system
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The reactivities of different p-quinones in the radical polymerization of methyl and tert-butyl acrylates were studied. The inhibitory effect of p-quinones decreases witn an increase in the volume and number of substituents. The radical polymerization of alkyl acrylates in the presence of tri-n-butylborane and p-quinones proceeds without gel effect by the “living” polymerization mechanism. UV spectroscopy showed that the reaction between the growth radical and p-quinone proceeds with different regioselectivity and depends on the nature of the latter. The obtained polyacrylates possess the capability of reinitiating polymerization. The reinitiation mechanism was studied by mass spectrometry (MALDI-TOF) and ESR spectroscopy. Gel permeation chromatography showed that, depending on the nature of p-quinone, macroinitiator polymers exhibit different activity in post-polymerization.
- Ludin,Kuznetsova, Yu. L.,Grishin,Kuropatov,Zaitsev
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p. 1859 - 1866
(2017/03/22)
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- BIOLOGICALLY ACTIVE COMPOUNDS SPECIFICALLY DELIVERED INTO MITOCHONDRIA
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This invention relates to biology and medicine and, in particular, can be used in medicine to make a pharmaceutical composition for targeted delivery of biologically active substances into mitochondria, driven by proton electro-chemical potential in the mitochondria. This invention also relates to the method to affect an organism by the targeted delivery of biologically active compounds to mitochondria. The invention can be useful in treatment of diseases or disorders associated with not normal functioning of mitochondria, in particular diseases associated with increased production of free radicals and reactive oxygen species.
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Paragraph 0090-0091
(2016/08/17)
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- Rh-Catalyzed Reactions of 1,4-Benzoquinones with Electrophiles: C-H Iodination, Bromination, and Phenylselenation
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Under Rh-catalyzed conditions, typically electrophilic 1,4-benzoquinones exhibit nucleophilic reactivity, such that exposure to appropriate electrophiles generates products of C-H iodination, bromination, and phenylselenation. This provides a mild and general method for direct halofunctionalization, and the first method that can achieve direct C-H phenylselenation of this compound class. The scope and limitations of the new protocols are outlined, and representative derivatizations are highlighted.
- Jardim, Guilherme A. M.,Bower, John F.,Da Silva Júnior, Eufranio N.
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p. 4454 - 4457
(2016/09/28)
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- Catalytic removal of organic colorants from water using some transition metal oxide nanoparticles synthesized under sunlight
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Transition metal oxides (TMO) constitute a most amazing class of materials with a wide range of properties and applications; therefore, their synthesis using a green approach is a necessity. As such, sunlight irradiation was employed to synthesize various TMO nanostructures (ZnO, CuO, Co3O4, NiO and Cr2O3) using water as a solvent. Nanoparticles obtained with distinct morphologies, such as nanotubes (ZnO; 3O4; 45-90 nm), needle-shaped (NiO; 2-25 nm) and nanobeads (Cr2O3; ~17 nm) were confirmed by TEM analysis. The significance of the synthesis is in its quick approach with no thermal heat involvement, reusable catalyst, cost effectiveness and ability to fabricate almost uniformly distributed nanoparticles with small sizes. The potential of the synthesized nanoparticles was examined in the treatment of simulated water containing hazardous dyes: Alizarin Red S (ARS) + Methylene Blue (MB). Interestingly, in a short period of 180 min, 88.24% of the dye mixture was, for the most part, completely degraded using Cr2O3 nano-needles, followed by 87.96% (ZnO) > 86.86% (CuO) > 85.89% (NiO) > 80.35% (Co3O4), depending on the sizes of the respective TMO nanoparticles. This is also supported by the finding of small and non-toxic by-products such as but-2-enal, sulfur trioxide and benzoquinone. With high potential observed in the removal of dyes, TMO nanoparticles have a bright future with respect to their use as important adsorbents in waste water treatment. The advantage of the present work lies in the green synthesis of nanoparticles and their application in helping to make our environment green.
- Shanker, Uma,Jassal, Vidhisha,Rani, Manviri
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p. 94989 - 94999
(2016/10/21)
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- A Facile and Selective Procedure for Oxidation of Hydroquinones using Silica Gel Supported Catalytic Cerium(IV) Ammonium Nitrate
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A new procedure for oxidation of hydroquinones to quinones using a silica gel supported cerium(IV) ammonium nitrate-NaBrO3 reagent has been developed. This simple, easy to prepare and use, heterogeneous reagent is highly selective towards oxidation of 1,4-dihydroxybenzenes and produces high yields of quinones. Waste generated by using this procedure is minimal.
- Ali, Mohammed Hashmat,Welker, Andrea,York, Crystal
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p. 3207 - 3211
(2015/10/19)
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- Quinones synthesis via hydrogen peroxide oxidation of dihydroxy arenes catalyzed by homogeneous and macroporous-polymer-supported ruthenium catalysts
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Ruthenium(II)/dimethyl phenyloxazoline (Ru(II)/dm-Pheox) complex 2a and its macroporous-polymeric-catalyst 4 were found to be very rapid and efficient catalysts in the hydrogen peroxide oxidation of 1,2- and 1,4-dihydroxy arenes. Most of the quinone products were delivered in 99% yield. The polymeric-catalyst 4 could be reused at least five times.
- Abu-Elfotoh, Abdel-Moneim,Tsuzuki, Kazuyuki,Nguyen, Tram Bao,Chanthamath, Soda,Shibatomi, Kazutaka,Iwasa, Seiji
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p. 8612 - 8617
(2013/09/12)
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- Iodine(III)-Mediated [3 + 2] cyclization for one-pot synthesis of benzo[ d ]isoxazole-4,7-diols in aqueous medium
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A one-pot [3 + 2] cycloadditive synthesis of benzo[d]isoxazole-4,7-diols in aqueous medium was carried out via nitrile oxides and benzoquinone intermediates by taking advantage of iodobenzene diacetate as an oxidant. This method can also be used to synthesize benzodiisoxazole-4,8-diols, isoxazolo[5,4-a]phenazines, and indazole-4,7-diols, which are difficult to obtain by classical methods.
- Hou, Yingwei,Lu, Shichao,Liu, Gang
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p. 8386 - 8395
(2013/09/24)
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- μ-oxo-bridged hypervalent iodine(III) compound as an extreme oxidant for aqueous oxidations
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We have found that in aqueous oxidations the -oxo-bridged hypervalent iodine trifluoroacetate reagent 1 {[(PhI(OCOCF]} is generally more reactive than the corresponding monomeric reagent, especially toward phenolic substrates. -Oxo-bridged 1 in aqueous media thus provided dearomatized quinones 3 in excellent yields in most cases compared to conventional phenyliodine(III) diacetate and bis(trifluoroacetate), as a result of the rapid oxidation of both phenols and naphthols 2. Furthermore, the oxidation reactions proceeded even in water using water-soluble -oxo oxidant 1, which has promise for -oxo-bridged reagent 1 to become the favored reagent over hydrophobic phenyliodine(III) diacetate and bis(trifluoroacetate). Georg Thieme Verlag Stuttgart New York.
- Dohi, Toshifumi,Nakae, Tomofumi,Takenaga, Naoko,Uchiyama, Teruyoshi,Fukushima, Kei-Ichiro,Fujioka, Hiromichi,Kita, Yasuyuki
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experimental part
p. 1183 - 1189
(2012/05/19)
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- PHARMACEUTICAL SUBSTANCES ON THE BASIS OF MITOCHONDRIALLY ADDRESSED ANTIOXIDANTS
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This invention relates to the fields of pharmaceutics and medicine, and, in particular, relates to the production and use of pharmaceutical substances on the basis of mitochondria-addressed compounds. The invention discloses methods for synthesis, purification and storage of mitochondria-addressed antioxidants, making it possible to produce said substances in a form and quality meeting the demands made on active ingredients of medicinal preparations - the pharmaceutical substances. The invention also discloses methods for design and selection of new mitochondria-addressed antioxidants having specified properties.
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Page/Page column 20
(2012/10/07)
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- PHARMACEUTICAL SUBSTANCES ON THE BASIS OF MITOCHONDRIA-ADDRESSED ANTIOXIDANTS
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This invention relates to the fields of pharmaceutics and medicine, and, in particular, relates to the production and use of pharmaceutical substances on the basis of mitochondria-addressed compounds. The invention discloses methods for synthesis, purification and storage of mitochondria-addressed antioxidants, making it possible to produce said substances in a form and quality meeting the demands made on active ingredients of medicinal preparations—the pharmaceutical substances. The invention also discloses methods for design and selection of new mitochondria-addressed antioxidants having specified properties.
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Page/Page column 17
(2012/10/18)
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- Synthesis of monomeric derivatives to probe memoquin's bivalent interactions
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Eight monomeric congeners, related to the multitarget lead candidate memoquin, were prepared and evaluated at multiple targets to determine their profile against Alzheimer's disease. 2-4 bind to AChE with similar low nanomolar affinities and function as effective inhibitors of amyloid aggregation. The most potent monovalent ligand 2 also inhibits BACE-1 in vitro and APP metabolism in primary chicken telencephalic neurons. (Figure presented)
- Bolognesi, Maria Laura,Chiriano, GianPaolo,Bartolini, Manuela,Mancini, Francesca,Bottegoni, Giovanni,Maestri, Valentina,Czvitkovich, Stefan,Windisch, Manfred,Cavalli, Andrea,Minarini, Anna,Rosini, Michela,Tumiatti, Vincenzo,Andrisano, Vincenza,Melchiorre, Carlo
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supporting information; experimental part
p. 8299 - 8304
(2012/02/14)
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- Construction of substituted benzene rings by palladium-catalyzed direct cross-coupling of olefins: A rapid synthetic route to 1,4-naphthoquinone and its derivatives
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Ring the changes: The direct cross-coupling of electron-deficient 1,4-benzoquinone or its derivatives with electron-rich alkyl vinyl ethers proceeds in a tandem manner to produce substituted benzene rings with good selectivity and in good to excellent yields (see scheme). The reaction has the potential for the rapid synthesis of diverse substituted benzene rings as it is not limited by substituent effects. Copyright
- Hu, Peng,Huang, Shijun,Xu, Jing,Shi, Zhang-Jie,Su, Weiping
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supporting information; experimental part
p. 9926 - 9930
(2011/11/06)
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- Synthesis and electrochemical properties of substituted para-benzoquinone derivatives
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A facile transformation of pentasubstituted tribromophenol derivatives to the corresponding alkyl-substituted dibromo-p-benzoquinones has been achieved using PbO2 as oxidizing agent in combination with 60% aq HClO4 in acetone in 70-72% yields. The electrochemical properties of these quinones were studied by means of cyclic voltammetry and compared with p-benzoquinone (BQ) and 2,3-dichloro-5,6-dicyano-benzoquinone (DDQ) recorded under identical experimental conditions.
- Khan, Faiz Ahmed,Choudhury, Sumit
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experimental part
p. 2541 - 2544
(2010/06/19)
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- Polymer incarcerated gold catalyzed aerobic oxidation of hydroquinones and their derivatives
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Polymer-incarcerated gold (PI Au) cluster catalysts mediated aerobic oxidation of hydroquinones and catechols to quinones very efficiently under mild conditions. The characteristic role of water in the reaction system was also observed. Copyright
- Miyamura, Hiroyuki,Shiramizu, Mika,Matsubara, Ryosuke,Kobayashi, Shu
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p. 360 - 361
(2008/09/20)
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- Aerobic oxidation of hydroquinone derivatives catalyzed by polymer-incarcerated platinum catalyst
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(Chemical Equation Presented) It's a lock-in! A remarkably wide substrate scope of hydroquinones are oxidized to quinones in high yields in a platinum-catalyzed process with as low as 0.05 mol% catalyst. The aerobic oxidation is catalyzed by platinum nanoclusters trapped in a styrene-based polymer network (see scheme, PI Pt=polymer-incarcerated nanoclusters). The catalyst could be reused at least 13 times without any loss of catalytic activity.
- Miyamura, Hiroyuki,Shiramizu, Mika,Matsubara, Ryosuke,Kobayashi, Shu
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supporting information; experimental part
p. 8093 - 8095
(2009/04/13)
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- METHOD OF ACTING UPON ORGANISM BY TARGETED DELIVERY OF BIOLOGICALY ACTIVE SUBSTANCES INTO M ITOCHONDRIA, PHARMACEUTICAL COMPOSITION FOR CARRYING OUT SAID METHOD, AND COMPOUND USED FOR THE PURPOSE
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This invention relates to biology and medicine and, in particular, can be used in medicine to make a pharmaceutical composition for targeted delivery of biologically active substances into mitochondria, driven by proton electro-chemical potential in the mitochondria. This invention also relates to the method to affect an organism by the targeted delivery of biologically active compounds to mitochondria. The invention can be useful in treatment of diseases or disorders associated with not normal functioning of mitochondria, in particular diseases associated with increased production of free radicals and reactive oxygen species.
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Page/Page column 15-16; 18
(2008/06/13)
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- Direct access to 1,4-dihydroxyanthraquinones: The Hauser annulation reexamined with p-quinones
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(Chemical Equation Presented) 3-Phenylsulfanylphthalides (e.g. 8a) readily react with p-benzoquinones in the presence of LiOtBu in THF to furnish 1,4-dihydroxyanthraquinones in good yields and one-pot operations.
- Mal, Dipakranjan,Ray, Sutapa,Sharma, Indrajeet
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p. 4981 - 4984
(2008/02/05)
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- Silica-gel-supported ceric ammonium nitrate (CAN): A simple and efficient solid-supported reagent for oxidation of oxygenated aromatic compounds to quinones
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A silica-gel-supported heterogeneous ceric ammonium nitrate (CAN) reagent has been developed for oxidizing oxygenated aromatics to quinones in nonaqueous media. The advantages of this procedure include excellent yields, mild reaction conditions, nonaqueous media, short reaction times, and easy product isolation. Copyright Taylor & Francis Group, LLC.
- Ali, Mohammed Hashmat,Niedbalski, Melinda,Bohnert, Gary,Bryant, Daniel
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p. 1751 - 1759
(2007/10/03)
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- Synthesis of benzo[b]benzo[2,3-d]thiophen-6,9-diones via palladium(II) acetate-mediated cyclization of 5-arylthiocyclohexa-2,5-diene-1,4-diones
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Palladium(II)-mediated oxidative cyclization of 5-arylthiocyclohexa-2,5- diene-1,4-diones 4 giving biologically important benzo[b]benzo[2,3-d]thiophene- 6,9-diones 2 has been performed with a stoichiometric amount of palladium(II) acetate in distillated acetic acid. Copyright Taylor & Francis Group, LLC.
- Ryu, Chung-Kyu,Choi, Ik Hwa,Park, Rae Eun
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p. 3319 - 3328
(2007/10/03)
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- The question of aromaticity in open-shell cations and anions as ion-radical offsprings of polycyclic aromatic and antiaromatic hydrocarbons
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(Chemical Equation Presented) Arene cation-radicals and anion-radicals result directly from the one-electron oxidation and reduction of many aromatic hydrocarbons, yet virtually nothing is known of their intrinsic (thermodynamic) stability and hence "aromatic character". Since such paramagnetic ion radicals lie intermediate between aromatic (Hueckel) hydrocarbons with 4n+2-electrons and antiaromatic analogues with 4n-electrons, we can now address the question of π-delocalization in these odd-electron counterparts. Application of the structure-based "harmonic oscillator model of aromaticity" or the HOMA method leads to the surprising conclusion that the aromaticity of these rather reactive, kinetically unstable arene cation and anion radicals (as measured by the HOMA index) is actually higher than that of their (diamagnetic) parent-contrary to conventional expectations.
- Rosokha, Sergiy V.,Kochi, Jay K.
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p. 9357 - 9365
(2007/10/03)
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- Retro Diels-Alder reaction under mild conditions: Experimental and theoretical studies
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The preliminary experimental and theoretical findings on the rDA reaction under milder reaction conditions were analyzed. It was found that required diene was immediately reacted with various dienophiles in a micellar medium to obtain the respective DA adducts in good yields. It was also found that the yield was considerably decreased even after prolonged refluxing conditions in DCM. The rDA reaction with spirocyclopentadiene as the diene can be carried out under mild reaction conditions. The results show that the lower kinetic barrier for this reaction has been identified as arising from greater stabilization of the transition state resulting from effective orbital interactions involving the cyclopropane bond orbitals.
- Kotha, Sambasivarao,Banerjee, Shaibal,Patil, Mahendra P.,Sunoj, Raghavan B.
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p. 1854 - 1856
(2008/02/07)
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- Preparation of 1,4-hydrobenzoquinones by the PCC/SiO2-promoted double oxidation of 3-cyclohexene-1,2-diols
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The PCC/SiO2-promoted double oxidation of 3-cyclohexene-1,2- diols, which were easily prepared by the two-step sequence of α-hydroxylation of various conjugated cyclohexenones and the subsequent nucleophilic carbonyl addition of alkyl anions, produced diversely substituted 1,4-hydrobenzoquinones. The Royal Society of Chemistry 2005.
- Kim, Hee Jin,Koo, Sangho
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p. 3479 - 3481
(2007/10/03)
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- A rapid and efficient synthesis of quinone derivatives: Ru(II)-or Ir(I)-catalyzed hydrogen peroxide oxidation of phenols and methoxyarenes
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Hydroquinone and methoxybenzene derivatives were catalytically oxidized promptly to the corresponding quinones in up to 99% yield. With a catalyst loading of 0.01 mol %, a maximum TON of 8.4 × 103 was attained in the case of Ru(II)-complex. Ru(II)(pybox-dh)(pydic) is able to enhance the hydrogen peroxide oxidation of substituted hydroquinones as well as methoxybenzenes, but Ir[(coe)2Cl]2 and Ir[(cod)Cl] 2 were found to be effective catalysts only for the former substrates under similar oxidation conditions.
- Iwasa, Seiji,Fakhruddin, Ahmad,Widagdo, Herman Setyo,Nishiyama, Hisao
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p. 517 - 520
(2007/10/03)
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- Nuclear amination catalyzed by fungal laccases: Reaction products of p-hydroquinones and primary aromatic amines
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(Chemical Equation Presented) Nuclear amination of p-hydroquinones with primary aromatic amines was catalyzed by fungal laccases (EC 1.10.3.2) from Trametes spec. and Myceliophthora thermophila. This is the first report of laccase-catalyzed synthesis of aminoquinones. Incubation of two compounds with laccase in the presence of oxygen resulted in the formation of the corresponding monoaminated or diaminated quinones. No hydroquinonoids were formed. Observed differences in the reaction courses for different p-hydroquinones and aromatic amines with different laccases are discussed.
- Niedermeyer, Timo H. J.,Mikolasch, Annett,Lalk, Michael
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p. 2002 - 2008
(2007/10/03)
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- Synthesis of indazol-4,7-dione derivatives as potential trypanocidal agents
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The synthesis of new indazol-4,7-dione derivatives via 1,3-dipolar cycloaddition of diazomethane with 2,3-dimethyl-1,4-benzoquinone (2) and 1,4-naphthoquinone (7) followed by N-alkylation of the pyrazol nitrogen atom of the corresponding quinones (3) and (8) with methyl chloroacetate is described. A series of amides from esters (5) and (10) were also obtained. These compounds were tested in vitro as potential antitrypanosomal agents. Compounds (4) and (8) were found to have significant activity.
- Tapia, Ricardo A.,Carrasco, Claudia,Ojeda, Scarlet,Salas, Cristian,Valderrama, Jaime A.,Morello, Antonio,Repetto, Yolanda
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p. 1093 - 1096
(2007/10/03)
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- Unified synthesis of quinone sesquiterpenes based on a radical decarboxylation and quinone addition reaction
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A unified synthesis of several quinone sesquiterpenes is described herein. Essential to this strategy is a novel radical addition reaction that permits the attachment of a fully substituted bicyclic core 16 to a variably substituted quinone 10. The addition product 15 can be further functionalized, giving access to natural products with a high degree of oxygenation at the quinone unit. The quinone addition reaction is characterized by excellent chemoselectivity, taking place only at conjugated and unsubstituted double bonds, and regioselectivity, being strongly influenced by the resonance effect of heteroatoms located on the quinone ring. These features were successfully applied to the synthesis of avarol (1), avarone (2), methoxyavarones (4, 5), ilimaquinone (6), and smenospongidine (7), thereby demonstating the synthetic value of this new method.
- Ling, Taotao,Poupon, Erwan,Rueden, Erik J.,Kim, Sun H.,Theodorakis, Emmanuel A.
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p. 12261 - 12267
(2007/10/03)
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