- Efficient reductive Claisen rearrangement of prop-2’-enyloxyanthraquinones and 2’-chloroprop-2’-enyloxyanthraquinones with iron powder in ionic liquids
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A rapid and selective iron-mediated reductive Claisen rearrangement of various prop-2’-enyloxyanthraquinones and 2’-chloroprop-2’-enyloxyanthraquinones to 1-hydroxy-2-(prop-2’-enyl)anthraquinones and anthrafurandiones is presented. All reactions are carried out in a mixture of ionic liquids, [Bzmim]Cl (1-benzyl-3-methylimidazolium chloride) and [Hmim]BF4 (1-methylimidazolium tetrafluoroborate), in short reaction times (5–35 min). Our study showed that 1-(prop-2’-enyloxy)anthraquinone is more active than 1-(2’-chloroprop-2’-enyloxy)anthraquinone to perform this rearrangement.
- Nadali, Samaneh,Khoshroo, Ali,Aghapour, Ghasem
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- Photochemistry of 1, n -Dibenzyloxy-9,10-anthraquinones
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Figure presented The photochemistry of a series of 9,10-anthraquinones with multiple benzyloxy substituents was investigated. In polar solvent, the expected Blankespoor oxidative cleavage reaction is the major reaction pathway, but in most cases, several minor products were observed. In nonpolar solvents, the abundance of these minor products increases dramatically. Four types of product were observed with the favored reaction pathway shifting with minor changes in substitution on the anthraquinone. Several types of product require cleavage of the C-O bond on the benzyloxy group and, apparently, follow a photo-Claisen-type mechanism. Others involve the expected 1,5-diradical but do not exhibit the single-electron transfer usually observed in the Blankespoor-type reaction. The results indicate the importance of considering the medium and photoredox behavior in anthraquinone photochemistry.
- Sarma, Saurav J.,Jones, Paul B.
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supporting information; experimental part
p. 3806 - 3813
(2010/08/20)
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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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- 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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- 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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- 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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p. 1109 - 1116
(2007/10/02)
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- DERIVATIVES OF ANTHRADITHIOLE-6,10-DIONE (OXADITHIAPENTALENEANTHRONE)
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The reaction of 1,5-dihydroxyanthrone with sulfur in a polar aprotic solvent leads to the 5-hydroxy derivative of anthradithiole-6,10-dione, which is a new condensed heterocyclic system and is the oxa analog of trithiapentaleneanthrone.During chlorination with sulfuryl chloride the compound changes into the 4,7,9-trichloro derivative, which is also formed when 1,5-dihydroxy-9,10-anthraquinone is heated with thionyl chloride and triethylamine.In the reaction of 5-hydroxyanthradithioledione with 2,6-di-tert-butylphenol or 1,5-dihydroxyanthrone in the presence of sulfur as oxidizing agent the hydrogen atom at position 7 is substituted with the formation of a C-C bond through position 4 or 10 respectively of the above-metioned C-nucleophile.The electronic structural characteristics of the new condensed system are discussed on the basis of x-ray crystalographic and spectral data.
- Gorelik, M. V.,Shteiman, V. Ya.,Trdatyan, V. A.,Tafeenko, V. A.,Mikhailova, T. A.
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p. 560 - 569
(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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- SOME EXPERIMENTS WITH AMINODIHYDROXYANTHRAQUINONES
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4-Amino-1-hydroxy-8-methoxyanthraquinone has been synthesized and alkylated with 1-nitropropane to give a mixture of 2- and 3-propyl compounds. Leuco-5-hydroxyquinizarin regioselectively reacts with n-propylamine and benzylamine to give 4-imino compounds, which are shown by (14)N n.m.r. spectroscopy to exist in solution as zwitterions. The benzylamine is regioselectively alkylated with propanal to give 4-benzylamino-1,5-dihydroxy-2-propylanthraquinone.
- Morris, Gareth A.,Mullah, Khairuzzaman B.,Sutherland, James K.
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p. 3303 - 3310
(2007/10/02)
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- STRUCTURE OF THE BORATE COMPLEXES OF α-AMINO AND α-HYDROXY-9,10-ANTHRAQUINONES AND THEIR REACTION WITH AMINES
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It was shown by 13C NMR that a redistribution of the bonds with partial localization of the 1,5- and 1,10-anthraquinonoid structures occurs during the transition from 1,5-diamino(dihydroxy)- and 1-amino(hydroxy)-9,10-anthraquinones respectively to their borate complexes.For this reason the boroacetates and fluoroborates of 1,5-dihydroxyanthraquinonones, 1-aminoanthraquinones, their N-alkyl and N-aryl derivatives, and 1,5-dihydroxyanthraquinone are capable of entering into amination under the influence of aromatic amines with substitution of the hydrogen atom at position 4 under mild conditions with the participation of atmospheric oxygen as oxidizing agent
- Gorelik, M. V.,Shapet'ko, N. N.,Arinich, L. V.,Tsurkan, A. I.,Kukushkina, M. L.
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p. 547 - 556
(2007/10/02)
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- Reduction of Aryldiazonium Salts to Arenes
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Aryldiazonium fluoroborates are smoothly reduced to the corresponding hydrocarbon derivatives by warming with DMF.When the amine has an electron donating substituent, the reaction proceeds at 65 deg C.When the amine has electron withdrawing substituents, the reaction proceeds rapidly at 25-45 deg C.Deamination of 2,4,6-trichlorobenzenediazonium fluoroborate with tetramethylurea gives acetaldehyde as an unexpected product together with 2,4,6-trichlorobenzene.The amines can also be deaminated with DMF without separation of the diazonium salt in aqueous or non-aqueous medium.
- Lahoti, R. J.,Parameswaran, V.,Wagle, D. R.
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p. 767 - 769
(2007/10/02)
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- Reactions of 1,5-Dichloroanthrachinone with Nucleophiles
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Reactions of 1,5-dichloroanthraquinone (1) with various nucleophiles were examined to evaluate possibilities for selective substitution. 1-Amino-5-chloroanthraquinone was obtained from 1 by reaction with (a) sodium azide in dimethyl sulfoxide and (b ammonia in the presence of potassium fluoride, but 1 with potassium in ammonia gave 3-chlorobenzoic acid.Conditions were found for preferential substitution in reactions of 1 with (c) 4-toluidine, (d) hexamethylphosphoric triamide, and (e) N-methylformamide.Reagent e is preferred for making 1-chloro-5-(methylamino)anthraquinone, though this compound predominates in mixtures produced when d is used.Potassium hydroxide in 2-ethoxyethanol converts 1 to the corresponding mono- and diethers of 1,5-dihydroxyanthraquinone, while sodium hydrosulfide and 1 give bis(5-chloroanthraquinonyl)sulfide.
- Ruediger, Edward H.,Kaldas, Magdy L.,Ghandi. Sham S.,Fedryna, Cristi,Gibson, Martin S.
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p. 1974 - 1978
(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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