- Oxidative Dearomatization of Phenols and Polycyclic Aromatics with Hydrogen Peroxide Triggered by Heterogeneous Sulfonic Acids
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We report herein a method for the oxidative dearomatization of phenols and bare polycyclic arenes into the corresponding quinoid derivatives using hydrogen peroxide. The reaction is catalyzed by sulfonic acids and best results were achieved using heterogenized species. The best results using phenols were achieved using a hybrid material, namely a perfluorinated polymer functionalized with sulfonic acid groups supported on silica. The dearomatization of polycyclic aromatic hydrocarbons performed better using the polymeric acid catalyst. These methods operate under mild conditions, using mild and benign oxidants and thus minimizing the formation of waste.
- Pancrazzi, Francesco,Maestri, Giovanni,Maggi, Raimondo,Viscardi, Rosanna
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supporting information
p. 5407 - 5414
(2021/10/25)
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- IBS-catalyzed regioselective oxidation of phenols to 1,2-quinones with oxone
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We have developed the first example of hypervalent iodine(V)-catalyzed regioselective oxidation of phenols to o-quinones. Various phenols could be oxidized to the corresponding o-quinones in good to excellent yields using catalytic amounts of sodium salts of 2-iodobenzenesulfonic acids (pre-IBSes) and stoichiometric amounts of Oxone as a co-oxidant under mild conditions. The reaction rate of IBS-catalyzed oxidation under nonaqueous conditions was further accelerated in the presence of an inorganic base such as potassium carbonate (K2CO3), a phase transfer catalyst such as tetrabutylammonium hydrogen sulfate (nBu4NHSO4), and a dehydrating agent such as anhydrous sodium sulfate (Na2SO4).
- Uyanik, Muhammet,Mutsuga, Tatsuya,Ishihara, Kazuaki
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experimental part
p. 8604 - 8616
(2012/10/07)
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- Transition metal catalyzed oxidations; 4. Improved method for the oxidation of 1- and 2-naphthols to 1,2-naphthoquinones
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A specific oxidation of 1- and 2-naphthols to the corresponding 1,2-naphthoquinones can be achieved by slow addition of the preformed complex of the naphthols with titanium tetraisopropylate with a syringe pump to excess tert-butyl hydroperoxide (TBHP). A previously described method gave mainly coupling products from the Michael reaction.
- Krohn,Rieger,Bruggmann
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p. 1141 - 1143
(2007/10/02)
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- Reactions of polar dienes with o-quinones
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The behaviour of various types of polar dienes towards halogenated ortho quinones has been investigated in a number of representative cases.As compared to the commonly used para analogues, o-quinones provide a wide range of products that indicate a keener response to the nature, number, and position of substituents on both reactants. 3-Halogenated-o-naphthoquinones 1 and 2 react smoothly with a representative vinologous ketene acetal 3, vinylketene acetals 4 and 5, and a monooxygenated diene 6 to provide variously substituted phenanthrenequinones 7-11.Only monooxygenated dienes on the other hand add to o-benzoquinones 14-16 and give convenient syntheses of the corresponding o-naphthoquinones 18-20.Key words: cycloaddition, o-naphthoquinones, phenanthrenequinones, regiospecificity.
- Paquet, Jacques,Brassard, Paul
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p. 1354 - 1358
(2007/10/02)
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- A New Synthesis of ortho-Quinones by Transition-Metal-Mediated Oxygenation of Phenols with tert-Butylhydroperoxide and the Mimoun Oxodiperoxo Molybdenum Complex * Py * HMPT
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A specific oxygenation of phenols to ortho-quinones can be effected by a combination of the transition metal complexes Ti(OiPr)4, VO(acac)2, Zr(acac)4, Zr(OnPr)4 and tert-butylhydroperoxide (TBHP) or * Py * HMPT.Naphthols, anthracenols, phenanthrols and donor substituted mononuclear phenols are readily converted into the corresponding 1,2-quinones.Unhindered ortho-naphthoquinones can yield binaphthyls with unreacted starting material by Michael addition. - Key Words: ortho-Quinones / tert-Butyl hydroperoxide / Phenols, oxygenation
- Krohn, Karsten,Rieger, Hagen,Khanbabaee, Karamali
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p. 2323 - 2330
(2007/10/02)
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