- Oxygenation of Dithranol by complexes of transition elements
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The oxygen activation in the dark by complexes of transition metals in the presence of the antipsoriatic compound dithranol (1a) is described.With the system CuCl/O2 an electron transfer oxygenation occurs, which simulates a 1O2-reaction, without an attack of 1O2.In the presence of Co-Salen/O2 the mechanism depends on the solvent and substrate, as already shown in the naphthalene-series.In methylenchloride dantrone (2), the radical product bisanthrone 3 and 1,8,10-trihydroxy-9-anthrone (4) are identified.The mechanistic particularity of this reaction in methylenchloride is discussed.
- Mueller, Klaus,Duchstein, Hans-Juergen
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- REGIOSPECIFIC SYNTHESIS OF QUINIZARIN DERIVATIVES BY CYCLOADDITION
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Cycloaddition of (E)-1,1,4-trimethoxy-1,3-butadiene (1) to naphthoquinones affords regiospecific syntheses of derivatives of 1,4-dihydroxyanthraquinone including the mould metabolites helminthosporin (21) and cynodontin (22).
- Cameron, Donald W.,Feutrill, Geoffrey I.,McKay, Peter G.
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- The Synthesis and Diels-Alder Reactions of 2-Prop-2-enylidene-1,3-dioxolan
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The synthesis and regiospecific Diels-Alder reactions of 2-prop-2-enylidene-1,3-dioxolan (1) are described.Reactions with 1,4-naphthoquinones (5) gave tetrahydroanthraquinones (6).The adduct of (1) with juglone (5d) could be further hydrolysed to 1,8-dihydroxy-9,10-anthraquinone (7).
- Ley, Steven V.,Mitchell, William L.,Radhakrishnan, Tarur V.,Barton, Derek H. R.
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- Total Synthesis of the Antimalarial Ascidian Natural Product Albopunctatone
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The first approaches to the 10′-anthronyl-2-anthraquinone skeleton have been devised, allowing two syntheses of the marine natural product albopunctatone. Both routes involve regioselective addition of a nucleophilic masked anthraquinone to a protected chrysazin derivative; the best affords albopunctatone in five steps and 35% overall yield. Albopunctatone exhibits potent inhibitory activity against Plasmodium falciparum and negligible toxicity to a range of other microbial pathogens and mammalian cells.
- Pullella, Glenn A.,Wdowiak, Adam P.,Sykes, Melissa L.,Lucantoni, Leonardo,Sukhoverkov, Kirill V.,Zulfiqar, Bilal,Sobolev, Alexandre N.,West, Nicholas P.,Mylne, Joshua S.,Avery, Vicky M.,Piggott, Matthew J.
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- The Formal Oxidative Addition of Electron-Rich Transoid Dienes to Bromonaphthoquinones
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This work established the idea that a halogen atom, such as bromine, will act as a control element in the regiospecific formation of a new carbon-carbon bond.The addition of the electron-rich end of a transoid diene to a bromojuglone dervative occurred exclusively at the unsubstituted carbon of the quinone.Thus, 2,2-dimethyl-4-methoxy-6-methylene-1,3-dioxa-2-sila-4-cyclohexene (3) and either 2- or 3-bromo-5-hydroxy-1,4-naphthoquinone (1 or 2) afforded the adducts 19 or 20 in 57percent or 71percent yield.Similarly, 2,2-dimethyl-6-methylene-4-(trimethylsiloxy)-1,3-diox-4-ene (4) and 1 gave 21 in 77percent yield.
- Grunwell, John R.,Karipides, Anastas,Wigal, Carl T.,Heinzman, Stephen W.,Parlow, John,et al.
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- One-electron Reactions of 1,5- and 1,8-Dihydroxy-9,10-anthraquinones. A Pulse Radiolysis Study
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Absorption characteristics of the semiquinone free radicals formed by one-electron reduction (using e-aq, CO2.- and CH3C.COHCH3 as the reductant) as well as the oxidation (using OH., O.- and N3. as the oxidants) of 1,5-dihydroxy-9,10-anthraquinone (1,5-DHAQ) and 1,8-dihydroxy-9,10-anthraquinone (1,8-DHAQ) have been studied by pulse radiolysis in pure isopropyl alcohol and in aqueous solutions containing various appropriate additives.The first acid dissociation constants for the reduced semiquinones were measured as pKa = 3.65 and 3.95 for 1,5-DHAQ and 1,8-DHAQ, respectively.Second-order rate constants for various formation and decay reactions have been determined.The one-electron reduction potentials (vs.NHE) were determined at pH 11, as E111 = -350 mV (for 1,5-DHAQ) and E111 = -377 mV (for 1,8-DHAQ), respectively.Differences with 1,4-dihydroxy-9,10-anthraquinone (quinizarin) are discussed.
- Pal, Haridas,Palit, Dipak K.,Mukherjee, Tulal,Mittal, Jai. P.
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- Inhibition of the prototropic tautomerism in chrysazine by p-sulfonatocalixarene hosts
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This study explores the interesting effect of p-sulfonatocalix[n]arene hosts (SCXn) on the excited-state tautomeric equilibrium of Chrysazine (CZ), a model antitumour drug molecule. Detailed photophysical investigations reveal that conversion of CZ from its more dipolar, excited normal form (N*) to the less dipolar, tautomeric form (T*) is hindered in SCXn-CZ host-guest complexes, which is quite unexpected considering the nonpolar cavity of the hosts. The atypical effect of SCXn is proposed to arise due to the partial inclusion or external binding of CZ with the hosts, which facilitates H-bonding interactions between CZ and the sulfonate groups present at the portals of the hosts. The intermolecular H-bonding subsequently leads to weakening of the pre-existing intramolecular H-bond network within CZ, and thus hinders the tautomerizaion process. Our results suggest that rather than the binding affinity, it is the orientation of CZ in the SCXn-CZ complexes, and its proximity to the portals of the host that plays a predominant role in influencing the tautomeric equilibrium. These observations are supported by quantum chemical calculations. Thermodynamic studies validate that SCXn-CZ interaction is essentially enthalpy driven and accompanied by small entropy loss, which is consistent with the binding mechanisms.
- Gharat, Poojan Milan,Maity, Dilip Kumar,Pal, Haridas,Dutta Choudhury, Sharmistha
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- Electron Paramagnetic Resonance, ENDOR and TRIPLE Resonance of some 9,10-Anthraquinone Radicals in Solution. Part 3. - Hydroxyanthraquinones
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EPR, ENDOR and TRIPLE resonance spectra have been recorded for 1,4-dihydroxy-9,10-anthraquinone, 1,5-dihydroxy-9,10-anthraquinone, 1,8-dihydroxy-9,10-anthraquinone, 2,6-dihydroxy-9,10-anthraquinone, 1,2-dihydroxy-9,10-anthraquinone, 1,2-dihydroxy-9,10-anthraquinone-3-sodium sulphonate and 1,2,5,8-tetrahydroxy-9,10-anthraquinone anion radicals.The hyperfine coupling constants and g factors ar given.Use of a modified additivity relationship allowed assignment of the constants.The spectra of deuterated radicals are discussed.
- Maekelae, Reijo,Vuolle, Mikko
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- A biocatalytic approach towards the preparation of natural deoxyanthraquinones and their impact on cellular viability
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Herein, a two-step chemoenzymatic process for the synthesis of medicinally important 3-deoxygenated anthra-9,10-quinones is developed. It involves a regio- and stereoselective reduction of hydroanthraquinones to (R)-configured dihydroanthracenones using an anthrol reductase of T. islandicus, followed by oxidation and dehydration to obtain deoxyanthraquinones in 65-80% yield. Comparison of the cell viability of normal human kidney HEK293 cells between anthraquinones and their deoxy derivatives revealed less toxicity for the latter.
- Das, Kiran,De, Arijit,Husain, Syed Masood,Maity, Biswanath,Mondal, Amit,Rajput, Anshul
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p. 3087 - 3090
(2022/02/21)
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- Anthraquinones as Photoredox Catalysts for the Reductive Activation of Aryl Halides
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Quinones are ubiquitous in nature as structural motifs in natural products and redox mediators in biological electron-transfer processes. Although their oxidation properties have already been used widely in chemical and photochemical reactions, the applications of quinones in reductive photoredox catalysis are less explored. We report the visible-light photoreduction of aryl halides (Ar–X; X = Cl, Br, I) by 1,8-dihydroxyanthraquinone. The resulting aryl radical anions fragment into halide anions and aryl radicals, which react through hydrogen abstraction or C–C bond-forming reactions. The active photocatalyst is generated from 1,8-dihydroxyanthraquinone by photoinduced single-electron reduction to the radical anion or subsequent protonation and further reduction (or vice versa) to the semiquinone anion. Subsequent visible-light excitation of the anthraquinone radical anion or semiquinone anion converts them into very potent single-electron donors. A plausible mechanism for the reaction is proposed on the basis of control experiments and spectroscopic investigations.
- Bardagi, Javier I.,Ghosh, Indrajit,Schmalzbauer, Matthias,Ghosh, Tamal,K?nig, Burkhard
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supporting information
p. 34 - 40
(2018/01/01)
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- Efficient and selective iron-mediated reductive Claisen rearrangement of propargyloxyanthraquinones to anthrafurandiones in ionic liquids
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An efficient and rapid method is described for the reductive Claisen rearrangement of different propargyloxyanthraquinones to anthra[1,2-b]furan-6,11-diones for first time using iron powder in a mixture of two ionic liquids, namely 1-methylimidazolium tetrafluoroborate [Hmim]BF4 and 1-benzyl-3-methylimidazolium chloride [Bzmim]Cl. The present method is able to execute single or double Claisen rearrangements of 1,4-or 1,5-bispropargyloxyanthraquinones selectively, so that the desired anthra(mono)furandiones or anthra(bis)furandiones are produced, respectively, as the major product.
- Nadali, Samaneh,Aghapour, Ghasem,Rafieepour, Zahra
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p. 1045 - 1051
(2017/10/03)
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- Synthesis, reactivity, catenation and X-ray crystallography of Ag + and Cu+ complexes of anthraquinone-based selenoethers: A luminescent chemodosimeter for Cu2+ and Fe3+
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Reaction of the PhSe- anion with 1,8-bis(2-bromoethoxy) anthracene-9,10-dione, 1,5-bis(2-bromoethoxy)anthracene-9,10-dione, 1,8-bis(2-bromoethylethyleneoxy)anthracene-9,10-dione in 1:1 ratio generates 1,8-bis(2-phenylselenoethoxy)anthracene-9,10-dione (2), 1,5-bis(2- phenylselenoethoxy)anthracene-9,10-dione (3) and 1,8-bis(2- phenylselenoethylethyleneoxy)anthracene-9,10-dione (4). The reaction of 2 with a methanolic solution of Ag(CH3CN)4BF4 and Cu(CH3CN)4BF4, yielded metal complexes 5 and 6, respectively. 3 formed a 1D coordination polymer (7) with Ag(CH 3CN)4BF4 in a 1:2 ratio. The anthraquinone in 3 exhibits π-π interactions with distances in a range of 3.512-3.840 A?. 2 acts as a chemodosimeter for Cu2+ and Fe3+ as it undergoes an aryl ether cleavage with Cu2+ and Fe3+, and produces the luminescent 1-hydroxy-8-(2-phenylselenoethoxy)anthracene-9,10- dione (8). Intramolecular hydrogen bonding in 8 is responsible for the red-orange (λmax 595 nm) emission. The X-ray structures of 5, 6, 7, and 8 are reported along with cyclic voltammetric analyses of new organoselenium compounds.
- Mariappan, Kadarkaraisamy,Basa, Prem Nath,Balasubramanian, Vinothini,Fuoss, Sarah,Sykes, Andrew G.
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p. 144 - 154
(2013/08/25)
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- Efficient selective oxidation of organic substrates using pyridinum sulfonate halochromate under solvent-free conditions and microwave irradiation: Experimental and theoretical study
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A convenient and rapid method has been developed for the selective oxidation of several types of alcohols to related carbonyl compounds under solvent-free conditions. In this study, the authors report the microwave-assisted selective oxidation of alcohols and a number of organic compounds with pyridinum sulfonate chlorochromate (PSCC) and pyridinum sulfonate fluorochromate (PSFC). The density functional theory calculations were made at B3LYP/6-31G* levels of theory and thermodynamic data supported the proposed mechanism involving formation of a halochromate ester, which showed that PSFC should be a more capable oxidant than PSCC. The oxidation products are easily obtained in short reaction time with good yields.
- Bekhradnia, Ahmad R.,Arshadi, Sattar
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experimental part
p. 705 - 710
(2012/08/08)
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- Highly selective three-step synthesis of rhein in chloroaluminate molten salt: preclusion of the Hayashi rearrangement
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An expeditious, three-step synthesis of rhein (2) was optimized starting from bis(N, N-diethyl)-5-methoxybenzene-1,3-dicarboxamide. The key final step, involving deprotection/cyclization of orihobenzoylbenzoic acid 9 in acidic chloroaluminate molten salts
- Gonnot, Vanessa,Antheaume, Cyril,Nicolas, Marc,Mioskowski, Charles,Baati, Rachid
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experimental part
p. 6205 - 6210
(2010/03/24)
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- Catalytic intramolecular crossed aldehyde-ketone benzoin reactions: A novel synthesis of functionalized preanthraquinones
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Stereochemically and functionally rich polycyclic compounds are obtained by the first crossed aldehyde-ketone benzoin reaction in excellent yield under mild reaction conditions (5-20 mol % thiazolium salt, 10-70 mol % DBU, tBuOH, 40°C, 30 min). This novel catalytic methodology offers a convenient approach to sophisticated molecular architectures useful for the stereocontrolled construction of polycyclic compounds as well as the fully regiocontrolled synthesis of anthra- and naphthoquinones. Copyright
- Hachisu, Yoshifumi,Bode, Jeffrey W.,Suzuki, Keisuke
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p. 8432 - 8433
(2007/10/03)
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- Dithranol reaction with nitroxide radicals in DMSO, a HPLC study
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Dithranol (1,8-dihydroxy-9-anthrone), an efficient drug for the topical treatment of psoriasis undergoes a complex chemical transformation after topical application. An absorption phase HPLC method has been developed and validated to follow the appearance of its oxidative products in a DMSO solution. In DMSO solution dithranol, chrysazin, and biantrone were monitored simultaneously by HPLC during autooxidation process, as well as in the presence of nitroxide radicals which increase the reaction rate. The kinetics of the very early stage of dithranol transformation is presented for the first time and discussed. Two unknown dithranol-derived intermediates were found and partially characterised.
- Ferlan, Andrej,Pecar,Schara
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p. 475 - 479
(2007/10/03)
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- Pathway of anthracene modification under simulated solar radiation
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Exposure of polycyclic aromatic hydrocarbons (PAHs) to sunlight results in rapid structural photomodification generally via oxidation reactions. These PAH modification products are in many cases more toxic than their parent compounds. In this study, anthracene (ANT), a rapidly photooxidized PAH, was irradiated with simulated solar radiation (SSR, 100 μmol m-2 s- 1) in aqueous solution to examine the photomodification pathway. The photoproducts formed were identified by HPLC. The ANT product profile after 9 h in SSR was very complex, with more than 20 compounds detected. The photoproducts formed were anthraquinones, benzoic acids, benzaldehydes and phenols showing the process to be oxidative in nature. Some of the anthraquinones were themselves subject to photooxidation, and were thus intermediates in the product pathway. The kinetics of ANT photooxidation revealed a pseudo first-order reaction with a half-life of 2 h under the SSR source used. The kinetics of product formation allowed deduction of a probable photomodification pathway. This study indicates that PAH photooxidation products are likely to exist as complex, dynamically changing mixtures in PAH contaminated aquatic environments.
- Mallakin, Ali,George Dixon,Greenberg, Bruce M.
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p. 1435 - 1441
(2007/10/03)
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- RHEIN DERIVATIVES AND NEW PROCESSES FOR PRODUCING RHEIN DERIVATIVES
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The present description relates to new anthraquinone-derivatives endowed with inhibitory activity of the serine proteinase enzymes, useful for the treatment of rheumatoid arthritis, acute respiratory syndrome of adult, and pulmonary emphysema, and to new processes for the preparation of rhein derivatives.
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- 10-α-aminoacyl-9(10H)-anthracenones: Inhibition of 12(S)-HETE biosynthesis and HaCaT cell growth
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1,8-Dihydroxy-9(10H)-anthracenones with a 10-α-aminoacyl group were synthesized using either a mixed-anhydride coupling method or Boc-protected oxazotidinediones. The novel anthracenones were evaluated as inhibitors of the biosynthesis of 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) in epidermal homogenate of mice and for inhibition of the growth of HaCaT keratinocytes. These cells were also tested for their susceptibility for the action of the most potent members of this series on plasma membrane integrity, in order to confirm that inhibition of cell growth is not a result of membrane damage induced by prooxidants released from anthracenones. Hydroxyl-radical generation as measure of the prooxidant potential of the compounds was determined by deoxyribose degradation. The most potent analogues of this series were equally potent as anthralin against 12(S)-HETE biosynthesis and keratinocyte proliferation, while oxygen-radical generation and the resulting damage to cell membrane was strongly reduced as compared to the antipsoriatic drug.
- Mueller, Klaus,Breu, Klaus
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- Acidity and stability of 10-substituted 1,8-dihydroxy-9(10H)-anthracenones
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The decomposition of 10-substituted anthralin derivatives in dimethyl sulfoxide and ethanol was determined. While 10-ω-phenylalkylidene derivatives were thoroughly stable, 10-ω-phenylacyl-substituted compounds were slowly degraded to danthron and the corresponding carboxylic acids. However, the stability of these derivatives was markedly improved as compared to that of anthralin. Determination of the pK(a) values showed that the ω-phenylacyl derivatives were somewhat stronger acids than anthralin, while ω-phenylalkylidene-substitution generally leaves the acidity of the anthralin part unchanged.
- Muller,Gawlik,Wiegrebe
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p. 359 - 362
(2007/10/02)
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- Method for dyeing keratinous fibres using a monohydroxyindole or dihydroxyindole and a non-oxidizing aromatic carbonyl derivative and dyeing agent
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The present invention relates to a method for dyeing keratinous fibers, characterized in that the following are applied to the fibers: a) a composition (A) containing, in a medium appropriate for dyeing, at least one monohydroxyindole or dihydroxyindole, this application being preceded or followed by the application of b) a composition (B) containing, in a medium appropriate for dyeing, at least one aromatic carbonyl derivative chosen from hydroxyacetophenones, hydroxybenzophenones, 2-hydroxy-1,4-benzoquinones, hydroxy-1,4-naphthoquinones,amino-1,4-naphthoquinones,hydroxy-9,10-anthraquinones and amino-9,10-anthraquinones. It also relates to the dyeing agents for carrying it out.
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- Substituent Effects in Anthrasemiquinones
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Electron spin resonance spectra have been obtained from series of 2-substituted anthrasemiquinones and of 3-substituted 1,8-dihydroxyanthrasemiquinones.The proton splittings are consistently assigned by means of linear correlation plots between splitting constants and a substituent-dependent paramater.All lines in the plots of he two series of compounds obey the following linear equation aRi = AixR + aHi where aHi and aRi are the splitting constants at position i before and after the substituent has been added.Ai is the slope of the line for the splittings from position i and xR is a constant characteristic of the substituent R. xR is comparable to the Hammett ? parameter.Electron-donating substituents at C-2 are shown to increase the spin densities at the positions 1 > 6 > 8, and to decrease them at the positions 4 > 3 > 7 > 5, with the strength of the effect indicated.Electron-withdrawing substituents have the opposite effect.Preliminary Hueckel molecular-orbital calculations qualitatively predict the observed correlations, solely by changing the parameter for the resonance integral.
- Pedersen, Jens A.
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p. 3223 - 3232
(2007/10/02)
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- Regioselective reactions of 1,4,5-trihydroxy-9,10-anthraquinone
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The regioselective alkylation of 1,4,5-trihydroxy-9,10-anthraquinone via reaction of its leuco compound is significant for the synthesis of anthracyclinones.In the presence of pyrrolidine in toluene solution, the leuco compound 3 selectively forms the 4-pyrrolidino enamine 11, which undergoes deamination to give 1,5-dihydroxy-9,10-anthraquinone.If an aldehyde is added, however, the enamine is alkylated, eventually yielding the 3-alkyl-1,4,5-trihydroxy-9,10-anthraquinone.Both of the above rections of 3 give high yields with 100percent regioselectivity.The enamine intermediate 11 has been trapped by oxidation to 4-pyrrolidino-1,5-dihydroxy-9,10-anthraquinone, which, after reduction, undergoes the same reactions as 3 giving either the alkylation or deamination product.The selective formation of 11 is explained terms of an enhancement of carbonyl group electrophilicity by a relay of hydrogen bonds.
- Broadbent, Douglas A.,Meschwitz, Wilfred,Stewart, John M.
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p. 2338 - 2341
(2007/10/02)
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- GENERATION AND ROLE OF SUPEROXIDE ION IN THE AUTOXIDATION OF 1,8-DIHYDROXY-9-ANTHRONE
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The autoxidation of anthralin (1,8-dihydroxy-9-anthrone, 1) at various pH values in Hepes buffer-acetonitrile is reported.The relative importance of the two main oxidation routes of anthralin, i.e. conversion to 1,8-dihydroxy-9,10-anthraquinone, 2, and to 1,8,1',8'-tetrahydroxy-10,10'-bianthrone, 3, is shown to be markedly dependent on pH.In particular, the product ratio of 2/3 is very low at pH 6 (0.05) but increases at higher pH (1.7 at pH 10.5).The reaction is accompanied by a significant production of superoxide at pH > 7.Addition of superoxide dismutase specifically inhibits the formation of 2.These findings are explained by assuming a direct interaction of the intermediate anthronyl radical 4 with superoxide, which ultimately leads to the quinone 2 at alkaline pH.
- D'Ischia, Marco,Prota, Giuseppe
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p. 511 - 514
(2007/10/02)
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- Studies on the oxidation behaviour of dithranol
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When Dithranol is oxidized in a weakly alkaline buffer by air oxygen one has to discuss two different oxidative pathways. Under homogeneous conditions (dithranol dissolved) the only oxidation product is dithranol-dimer (and subsequently dithranol-brown) whereas under heterogeneous conditions (dithranol suspended) mainly chrysazine (dantron) is produced, which does not alter under the chosen conditions. These circumstances may play an important part in the dithranol therapy of psoriasis.
- Schaltegger
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p. 666 - 668
(2007/10/02)
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- INTERACTION OF ANTHRALIN WITH CYSTEINE : A NEW ENTRY INTO THE CHEMISTRY OF BIOLOGICALLY ACTIVE ANTHRONES.
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Evidence is reported that under physiological conditions anthralin (I), an antipsoriatic drug, reacts with cysteine to give an ether-insoluble adduct which was formulated as 1,8-dihydroxy-10-(2-amino-2-carboxyethylthio)-9-anthrone (III) by model studies and unambiguous synthesis.
- d'Ischia, M.,Privitera, A.,Prota, G.
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p. 4837 - 4840
(2007/10/02)
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- Regiospecific Synthesis of Quinizarin and Naphthazarin Derivatives by Cycloaddition
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The diene (E)-1,1,4-trimethoxybuta-1,3-diene underwent regiospecific cycloaddition to derivatives of 2(3)-chloro-1,4-naphthoquinone.The resulting adducts were aromatized to give 1,4-dioxygenated anthraquinones.The latter were obtained as derivatives of quinizarin dimethyl ether or of quinizarin monomethyl ether depending on the conditions of aromatization.Cycloaddition of the diene to non-halogenated naphthoquinones proceeded similarly, orientation being controlled by substituents in the benzenoid ring.Analogous reaction of the diene with benzoquinones gave 5,8-dioxygenated naphthoquinones (naphthazarins), generally in limited yield.The procedure has been applied to synthesis of the mould metabolites helminthosporin and cynodontin
- Cameron, Donald W.,Feutrill, Geoffrey I.,McKay, Peter G.
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p. 2095 - 2109
(2007/10/02)
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- Chemistry of Quinones. Part 6. The Selective Hydrolysis of α-Acetoxyanthraquinones and Related Compounds by Trifluoroacetic Acid Containing Small Amounts of Water
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Acetoxy- or benzoyloxy-substituents adjacent to the carbonyl groups of anthraquinone, 1,4-naphthoquinone, naphthacene-5,12-quinone, benzophenone, and methyl benzoate are selectively converted into hydroxy-groups by treatment with trifluoroacetic acid containing small amounts of water.In the absence of water a reversible acidolysis occurs.Water reacts with the acylating agent, thus preventing the reverse reaction.Evidence is presented that the hydrolyses are of the AAC1 type.
- Harrison, Charles R.,Hodge, Philip,Khan, Naeem
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p. 1592 - 1594
(2007/10/02)
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