- Base-Promoted Reactions of Hydroxyquinones with Pyrones: A Direct and Sustainable Entry to Anthraquinones and Naphthoquinones
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Hydroxybenzoquinones and hydroxynaphthoquinones react with methyl coumalate and 5-cyanopyrone to generate anthraquinones and naphthoquinones in good to excellent yields.
- Kraus, George A.,Yu, Huangchao
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Read Online
- Design, synthesis and α-glucosidase inhibition study of novel embelin derivatives
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Embelin is a naturally occurring para-benzoquinone isolated from Embelia ribes (Burm. f.) of the Myrsinaceae family. It was first discovered to have potent inhibitory activity (IC50 = 4.2 μM) against α-glucosidase in this study. Then, four seri
- Chen, Wenhua,Chen, Xiaole,Gao, Min,Hong, Weiqian David,Jian, Rongchao,Li, Yuling,Sheng, Zhaojun,Tang, Xiaowen,Wu, Panpan,Zhang, Kun,Zhao, Denggao,Zheng, Xi
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p. 565 - 573
(2020/02/15)
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- COMPOUND FOR HARD MASK, HARD MASK COMPOSITION COMPRISING SAID COMPOUND, AND METHOD FOR FORMING SEMICONDUCTOR ELEMENT FINE PATTERN USING SAID COMPOUND
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The present invention relates to a compound for a hard mask, a hard mask composition comprising the same, and a method for forming a fine pattern of a semiconductor element using the same. The compound for a hard mask according to the present invention has high solvent solubility that can be applied to a spin coating method, and thus it is possible to prepare a hard mask composition that not onlyhas excellent gap filling performance, but also has excellent heat resistance and etching resistance after curing. In addition, it is possible to provide a fine pattern forming method of a semiconductor element using the same.
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Paragraph 0257-0262
(2020/12/15)
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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, characterization, spectral property, Hirshfeld surface analysis and TD/DFT calculations of 2, 6-disubstituted benzobisoxazoles
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An effective and clean aerobic oxidative method for the synthesis of 2,6-disubstituted benzobisoxazole using the free radical catalysis was obtained. 2, 6-Di(pyridin-4-yl)-benzo[1,2-d:4,5-d']bisoxazole was synthesized and characterized by 1H an
- Hu, Qi,Yue, Yong-Hao,Chai, Lan-Qin,Tang, Li-Jian
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p. 508 - 518
(2019/08/01)
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- Steric effects of bulky tethered arylpiperazines on the reactivity of Co-Schiff base oxidation catalysts—a synthetic and computational study
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New C2-symmetric and C2-asymmetric Co-Schiff base catalysts tethered to arylpiperazine units were synthesized and used to oxidize phenolic lignin models to para-benzoquinones. Synthetic approaches to these catalysts were optimized to include fewer steps and broaden the types of catalyst structures available. In contrast to conventional Co-Schiff base catalysts, these systems induce phenolic oxidation in the absence of an external axial base, simplifying the process. Asymmetric catalysts bearing a phenylethylene or diphenylmethyl piperazine substituent display the highest catalytic activity observed to date for the conversion of S-models to 2,6-dimethoxybenzoquinone (DMBQ). Computational analysis shows that more reactive catalysts populate conformations that favor oxidation in preference to non-productive decomposition routes. This balance between catalyst reactivity and catalyst deactivation is optimized by inclusion of sufficient steric bulk around the periphery of the Schiff base ligand, reducing catalyst deactivation and allowing oxidations to proceed in the absence of an added axial ligand.
- Key, Rebecca E.,Elder, Thomas,Bozell, Joseph J.
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p. 3118 - 3127
(2019/05/10)
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- A Catalytic Oxidative Quinone Heterofunctionalization Method: Synthesis of Strongylophorine-26
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The preparation of heteroatom-substituted p-quinones is ideally performed by direct addition of a nucleophile followed by in situ reoxidation. Albeit an appealing strategy, the reactivity of the p-quinone moiety is not easily tamed and no broadly applicable method for heteroatom functionalization exists. Shown herein is that Co(OAc)2 and Mn(OAc)3?2 H2O act as powerful catalysts for oxidative p-quinone functionalization with a collection of O, N, and S nucleophiles, using oxygen as the terminal oxidant. Preliminary mechanistic observations and the first synthesis of the cytotoxic natural product strongylophorine-26 is presented.
- Yu, Wanwan,Hjerrild, Per,Jacobsen, Kristian M.,Tobiesen, Henriette N.,Clemmensen, Line,Poulsen, Thomas B.
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supporting information
p. 9805 - 9809
(2018/07/31)
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- ONO-pincer ruthenium complex-bound norvaline for efficient catalytic oxidation of methoxybenzenes with hydrogen peroxide
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The enhanced catalytic activity of ruthenium complex-bound norvaline Boc-l-[Ru]Nva-OMe 1, in which the ONO-pincer ruthenium complex Ru(pydc)(terpy) 2 is tethered to the α-side chain of norvaline, has been demonstrated for the oxidation of methoxybenzenes to p-benzoquinones with a wide scope of substrates and unique chemoselectivity.
- Yoshida, Ryota,Isozaki, Katsuhiro,Yokoi, Tomoya,Yasuda, Nobuhiro,Sadakane, Koichiro,Iwamoto, Takahiro,Takaya, Hikaru,Nakamura, Masaharu
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supporting information
p. 7468 - 7479
(2016/08/16)
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- Unusual, chemoselective etherification of 2-hydroxy-1,4-naphthoquinone derivatives utilizing alkoxymethyl chlorides: Scope, mechanism and application to the synthesis of biologically active natural product (±)-lantalucratin C
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A novel etherification of 2-hydroxy-1,4-naphthoquinone derivatives with alkoxyalkyl chlorides and hydride bases is described. Precise study of the conditions and substrate scope suggested that the reaction occurs specifically in the molecule having a 2-hydroxy-1,4-benzoquinone skeleton. A chemoselective O-methylation reaction was achieved to afford a synthetically important intermediate, which offered easy access to a natural product possessing anti-tumor activity.
- Ogata, Tokutaro,Yoshida, Tomoyo,Shimizu, Maki,Tanaka, Manami,Fukuhara, Chie,Ishii, Junko,Nishiuchi, Arisa,Inamoto, Kiyofumi,Kimachi, Tetsutaro
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p. 1423 - 1432
(2017/02/15)
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- Tetramethoxybenzene is a good building block for molecular wires: Insights from photoinduced electron transfer
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Two donor bridge-acceptor molecules with terminal triarylamine and Ru(bpy)32+ (bpy = 2,2′-bipyridine) redox partners were synthesized and investigated by cyclic voltammetry, optical absorption, luminescence, and transient absorption spectroscopy. The two dyads differ only by the central bridging unit, which was tetramethoxybenzene (tmb) in one case and unsubstituted phenylene (ph) in the other case. Photoirradiation of the Ru(bpy)32+ complex of the two dyads triggers intramolecular electron transfer from the triarylamine to the 3MLCT-excited metal complex, and this process occurs with time constants of 1.5 and 6.8 ns for the tmb- and ph-bridged dyads, respectively. Thermal electron transfer in the reverse direction then leads to disappearance of the photoproduct with a time constant of 10 ns in both dyads. The faster rate of photoinduced charge transfer in the tmb-bridged dyad can be understood in the framework of a hole-tunneling model in which the electron-rich tmb bridge imposes a more shallow barrier than the less electron-rich ph spacer. Until now tmb-based molecular wires have received very little attention, and alkoxy substituents have been mostly used for improving the solubility of oligo-p-phenylene vinylene (OPV) and oligo-p-phenylene ethynylene (OPE) wires. Our study illustrates how four alkoxy-substituents on a phenylene backbone can have a significant influence on the charge-transfer properties of a molecular wire, and this is relevant in the greater context of a future molecular electronics technology.
- Heinz, Luisa G.,Yushchenko, Oleksandr,Neuburger, Markus,Vauthey, Eric,Wenger, Oliver S.
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p. 5676 - 5684
(2015/06/16)
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- Design, synthesis, and SAR of embelin analogues as the inhibitors of PAI-1 (plasminogen activator inhibitor-1)
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The natural product embelin was found to have PAI-1 inhibitory activity with the IC50 value of 4.94 μM. Based on the structure of embelin, a series of analogues were designed, synthesized, and evaluated for their ability to inhibit PAI-1. The SAR study on these compounds disclosed that the inhibitory potency largely depended on the hydroxyl groups at C2 and C5, and the length of the alkyl chains at C3 and C6. Compound 11 displayed the best PAI-1 inhibitory potency with the IC50 value of 0.18 μM.
- Chen, Fanglei,Zhang, Guiping,Hong, Zebin,Lin, Zhonghui,Lei, Min,Huang, Mingdong,Hu, Lihong
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supporting information
p. 2379 - 2382
(2014/05/20)
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- Synthesis, crystal structure and fluorescence behavior of 2,6-Di(thiophen-2-yl)-benzo[1,2-d:4,5-d']bisoxazole
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An effective and clean new aerobic approach for the synthesis of 2,6-disubstituted benzobisoxazole by using a one-pot reaction of an organic aminoxyl radical as the catalyst is reported. 2,6- Di(thiophen-2-yl)-benzo[1,2-d : 4,5-d]bisoxazole was synthesized with catalysis by the free radical 4-methoxy-TEMPO and characterized by 1H and 13C NMR spectroscopy, HRMS, as well as by elemental analysis, UV/Vis and emission spectroscopy. The crystal structure of the title compound has been determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic space groupC2/c with a=12.531(1), b=3.8960(2), c = 28.733(2) A, β = 100:760(1), Z = 4. Through intermolecular weak C-H O hydrogen bonding and p-p stacking interactions, a supramolecular 3D structure is formed.
- Chai, Lan-Qin,Zhang, Yu-Li,Tong, Jun-Feng,Liu, Gang
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p. 239 - 244
(2013/05/22)
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- Synthesis of a focused chemical library based on derivatives of embelin, a natural product with proapoptotic and anticancer properties
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The synthesis of new derivatives of embelin, a natural inhibitor of X-linked inhibitor of apoptosis protein (XIAP) is described. The design of these new molecules involved introduction of aromatic groups directly linked to the benzoquinone core. To allow a large flexibility in the nature and the length of the added chain, the strategy involves first aSuzuki-Miyaura reaction with functionalized aromatics, yielding a first generation of molecules. Then, by appropriate use of the functional groups, a second generation of representative embelin derivatives was prepared.
- Viault, Guillaume,Gree, Danielle,Das, Saibal,Yadav, Jhillu Singh,Gree, Rene
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experimental part
p. 1233 - 1241
(2011/04/17)
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- Accelerated hole transfer across a molecular double barrier
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We report on a dyad in which photoinduced hole transfer through a non-uniform molecular double barrier is more than one order of magnitude more rapid than hole transfer across a comparable uniform (rectangular) tunneling barrier.
- Hanss, David,Walther, Mathieu E.,Wenger, Oliver S.
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supporting information; experimental part
p. 7034 - 7036
(2010/10/19)
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- A synthetic study on bauhinoxepin J: Construction of a dibenzo[bf]oxepin ring system by a DDQ-promoted oxidative dearomatization-cyclization approach
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Efforts to construct a dibenzo[b,f]oxepin ring system for a synthesis of bauhinoxepin J are described. A DDQ-promoted oxidative dearomatization-cyclization of the 2-phenoxyethyl-substituted tetramethoxybenzene was used to construct a tricyclic quinone mon
- Yoshida, Masahiro,Maeyama, Yohei,Shishido, Kozo
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experimental part
p. 623 - 629
(2010/04/27)
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- An approach to 3,6-disubstituted 2,5-dioxybenzoquinones via two sequential Suzuki couplings. Three-step synthesis of leucomelone
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(Chemical Equation Presented) Two sequential Suzuki coupling reactions have been developed for efficient synthesis of synthetically and biologically important 3,6-disubstituted 2,5-dioxybenzoquinone architectures in a highly chemoselective controlled mann
- Gan, Xianwen,Jiang, Wei,Wang, Wei,Hu, Lihong
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supporting information; body text
p. 589 - 592
(2009/07/24)
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- t-butyl hydroperoxide oxidative dealkylation of hydroquinone ethers to 1,4-quinones
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Various organoselenium compounds (diselenides, benzisoselenazol-3(2H)-ones, and 1,3,2-thiaselenazolones) are effective catalysts for oxidative dealkylation of hydroquinone ethers with t -butyl hydroperoxide to 1,4-quinones. The reactions is most efficient when t -butyl hydroperoxide in the presence of poly(bis-1,2-phenyl) diselenide is used as an oxidizing agent. In this way 1,4-benzo and 1,4-naphthoquinones are produced in good to high yields. Copyright Taylor & Francis Group, LLC.
- Wojtowicz, Halina,Mlochowski, Jacek,Syper, Ludwik,Yadav, Hardeo
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p. 1991 - 2000
(2007/10/03)
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- Fluorous-tagged indolylboron for the diversity-oriented synthesis of biologically-attractive bisindole derivatives
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The diversity-oriented synthesis of bisindole derivatives to construct concise libraries using consecutive cross-coupling reactions and prepare new sulfonamide type fluorous protecting groups is presented. The Royal Society of Chemistry 2006.
- Kasahara, Takahiro,Kondo, Yoshinori
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p. 891 - 893
(2008/02/08)
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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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- Synthesis of methoxy-substituted phenols by peracid oxidation of the aromatic ring
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A novel benign protocol for the preparation of hydroxy-methoxybenzene derivatives is disclosed. By utilizing this protocol, activated aromatic compounds such as l,3-dimethoxy-2-methyl-benzene and 1-(2,6-dimethoxyphenyl) ethanone are smoothly converted to the corresponding monohydroxylated compound. The reaction can be considered to be a normal aromatic electrophilic substitution reaction, and the regioselectivity for the reaction thus follows the similar rules as for electrophilic substitutions. The protocol is composed by benign reagents, namely, hydogenperoxide, acetic acid, and p-toluene sulfonic acid, which lead to the production of ethaneperoxoic acid in situ. The ethaneperoxoic acid operates as the hydroxylating reagent. The hydroxylation reaction is completed within a short period and requires moreover only mild experimental conditions, which make this novel protocol a green, cheap, and rapid process leading to hydroxy-methoxybenzene derivatives. The proposed reaction mechanism is supported by density functional theory and NMR spectroscopy experiments. The mechanism is constituted by two discrete steps: (a) addition of OH+ to the most nucleophilic carbon atom of the aromatic ring, which is the rate-determining step, and (b) the loss of the proton from the aromatic ring.
- Bjorsvik, Hans-Rene,Occhipinti, Giovanni,Gambarotti, Cristian,Cerasino, Leonardo,Jensen, Vidar R.
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p. 7290 - 7296
(2007/10/03)
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- Total synthesis and biological evaluation of the nakijiquinones
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The Her-2/Neu receptor tyrosine kinase is vastly overexpressed in about 30% of primary breast, ovary, and gastric carcinomas. The nakijiquinones are the only naturally occurring inhibitors of this important oncogene, and structural analogues of the nakijiquinones may display inhibitory properties toward other receptor tyrosine kinases involved in cell signaling and proliferation. Here, we describe the first enantioselective synthesis of the nakijiquinones. Key elements of the synthesis are (i) the reductive alkylation of a Wieland - Mieschertype enone with a tetramethoxyaryl bromide, (ii) the oxidative conversion of the aryl ring into a p-quinoid system, (iii) the regioselective saponification of one of the two vinylogous esters incorporated therein, and (iv) the selective introduction of different amino acids via nucleophilic conversion of the remaining vinylogous ester into the corresponding vinylogous amide. The correct stereochemistry and substitution patterns are completed by conversion of two keto groups into a methyl group and an endocyclic olefin via olefination/reduction and olefination/isomerization sequences, respectively. This synthesis route also gave access to analogues of nakijiquinone C with inverted configuration at C-2 or with an exocyclic instead of an endocyclic double bond. Investigation of the kinase-inhibiting properties of the synthesized derivatives revealed that the C-2 epimer 30 of nakijiquinone C is a potent and selective inhibitor of the KDR receptor, a receptor tyrosine kinase involved in tumor angiogenesis. Molecular modeling studies based on the crystal structure of KDR and a model of the ATP binding site built from a crystal structure of FGF-R revealed an insight into the structural basis for the difference in activity between the natural product nakijiquinone C and the C-2 epimer 30.
- Stahl,Kissau,Mazitschek,Huwe,Furet,Giannis,Waldmann
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p. 11586 - 11593
(2007/10/03)
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- Selenium(IV) oxide catalyzed oxidation of aldehydes to carboxylic acids with hydrogen peroxide
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A convenient method for oxidative transformation of aromatic, heteroaromatic and aliphatic aldehydes into carboxylic acids is presented. It is based on the oxidation of aldehydes in THF using 30% hydrogen peroxide in the presence of 5 molar % of selenium(IV) oxide. The scope and limitation of the method are discussed.
- Brzaszcz,Kloc,Maposah,Mlochowski
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p. 4425 - 4434
(2007/10/03)
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- Preparation and structure-activity relationships of novel asterriquinone derivatives
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Asterriquinone (ARQ, la) is an antitumor metabolite of Aspergillus terreus IFO 6123. To gain insight into the structure-activity relationships of ARQ, a series of chemically modified derivatives (1 - 6), the ARQ analogues (b - e) and the 2,5-dihydroxy-p-benzoquinone analogues (f - h), were prepared, and cytotoxic activity against mouse leukemia P388 cells investigated. Results indicated that: 1) at least one hydroxy group or acetoxy group in the p-benzoquinone moiety is important to exhibit cytotoxicity; 2) in the p-benzoquinone moiety, a single methoxy group and/or one acetoxy group substitution showed more potent cytotoxicity than when two hydroxy groups are substituted (1); 3) the indole ring is important for the cytotoxicity of ARQ analogues; 4) the 1,1-dimethyl-2-propenyl group in the indole ring is not important for the cytotoxic activity of ARQ.
- Kaji, Akira,Kimura, Kengo,Teranishi, Masanori,Kiriyama, Noriki,Nomura, Masaaki,Miyamoto, Ken-Ichi
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p. 1325 - 1329
(2007/10/03)
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- Rearrangement of allyl aryl ethers III1 reaction of alkoxyhydroquinone with cycloalkenediols
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Cycloalkenobezofurans 5a-d were prepared in one-pot reaction from methoxyhydroquinone, 2,6- and 2,3-dialkoxyhydroquinone (1) with cycloalkenediol (2). Reaction between the isomeric 2,5-dialkoxyhydroquinones (9) with diol 2 led to the formation of monoalkoxybenzofurans 5d-g with the loss of an alkoxy group.
- Novak, Lajos,Kovacs, Peter,Pirok, Gyoergy,Kolonits, Pal,Hanania, Michel,Donath, Katalin,Szantay, Csaba
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p. 9789 - 9798
(2007/10/03)
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The structures of seven di-or tetrasubstituted p-benzoquinone derivatives O=C(XC=CH)2C=O and O=C(XC=CX)2C=O with substituents X = -OCH3, -N(CH2)5, -N(CH2CH2)2O, -Cl, -
- Bock, Hans,Nick, Sabine,Seitz, Wolfgang,Naether, Christian,Bats, Jan W.
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p. 153 - 171
(2007/10/03)
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- Selective alkoxylation of 1,4-quinones
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1, 4-Quinones have been alkoxylated selectively at the active quinonoid position using alkanols and alkenol in the presence of (a) Raney nickel, (b) silica gel and (c) Cubronze with iodine.
- Thapliyal,Seth,Sharma,Kanodia,Singh,Khanna
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p. 381 - 384
(2007/10/03)
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- Partial deacetylation of asterriquinone diacetate by aqueous sodium bicarbonate in pyridine
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Asterriquinone (ARQ); 2,5 -bis[1-(1,1-dimethyl-2-propenyl)-1H-indol-3- yl]-3,6-dihydroxy-2,5-cyclohexadiene-1,4-dione and ARQ monoacetate are metabolites from mycelium of Aspergillus terreux IFO 6123. ARQ diacetate was convened into ARQ monoacetate by treatment with 5% aq. NaHCO3 in pyridine at 80°C for 5 min, and the yield was 93.4%. Similarly, by treatment with 5% aq. NaHCO3 in acetone at room temperature, 2,5-diacetoxy-p-xyloquinone and 2,5- diacetoxy-p-benzoquinone were convened into 2-acetoxy-5-hydroxy-p-xyloquinone (yield, 85.8%) and 2-acetoxy-5-hydroxy-p-benzoquinone (yield, 66.7%), respectively.
- Kaji,Kimura,Iwata,Kiriyama
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p. 1818 - 1820
(2007/10/03)
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- Oxidation of Methoxy- and/or Methyl-Substituted Benzenes and Naphthalenes to Quinones and Phenols by H2O2 in HCOOH
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The oxidation of a number of arenes (methoxybenzenes, methylbenzenes, and naphthalenes) to quinones and phenols by H2O2 in HCOOH has been examined.Methoxybenzenes were much more easily oxidized to p-benzoquinones than methylbenzenes (e.g., 1,3,5-trimethoxybenzene was oxidized to 2,6-dimethoxy-p-benzoquinone in a 75percent yield and 1,2,4-trimethylbenzene to 2,3,5-trimethyl-p-benzoquinone in a 16percent yield).Electron-withdrawing substituents, such as nitro, cyano, and chloro groups, lowered the conversion of reactants and changed the product selectivity from quinones to phenols.Methoxybenzonitriles were oxidized to corresponding phenols in a moder ate yield (e.g., 2,6-dimethoxybenzonitrile to 3-hydroxy-2,6-dimethoxybenzonitrile in a 39percent yield and a 64percent selectivity).
- Orita, Hideo,Shimizu, Masao,Hayakawa, Takashi,Takehira, Katsuomi
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p. 1652 - 1657
(2007/10/02)
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- COPPER-CATALYZED AEROBIC OXIDATION OF METHOXYPHENOLS
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A variety of methoxyphenols were selectively converted methoxy-p-benzoquinones by the use of copper-catalyzed aerobic oxidation.
- Matsumoto, Masakatsu,Kobayashi, Hisako,Hotta, Yasushi
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p. 515 - 520
(2007/10/02)
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- Oxidations with Lead Tetraacetate. II. Oxidations of 2,2-Disubstituted 1,3-Benzodioxoles
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The oxidation of 2,2-disubstituted 1,3-benzodioxoles by lead tetraacetate proceeds readily to give 5-acetoxy and 5,6-dione derivatives as main products. 5,6-Diacetoxy compuonds and 5-carboxy derivatives are found in some instances as minor products.Oxidation of benzodioxoles substituted at the 5 and 6 positions with methoxyl groups or with a second dioxole ring results in oxidative loss of the dioxole ring.Relative effects of these substitutions on reactivity have been evaluated.The mechanism of ο-quinone formation is discussed and is postulated to occur via a tetraacetoxy intermediate.The 5-acetoxy derivatives and the ο-quinones, by hydrolysis and reduction respectively, serve as sources of 5-hydroxy and 5,6-dihydroxy benzodioxoles.
- Cole, Edward R.,Crank, George,Minh, H. T. Hai
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p. 527 - 543
(2007/10/02)
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