- Regioselectivity of Hydroxyl Radical Reactions with Arenes in Nonaqueous Solutions
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The regioselectivity of hydroxyl radical addition to arenes was studied using a novel analytical method capable of trapping radicals formed after the first elementary step of reaction, without alteration of the product distributions by secondary oxidation processes. Product analyses of these reactions indicate a preference for o- over p-substitution for electron donating groups, with both favored over m-addition. The observed distributions are qualitatively similar to those observed for the addition of other carbon-centered radicals, although the magnitude of the regioselectivity observed is greater for hydroxyl. The data, reproduced by high accuracy CBS-QB3 computational methods, indicate that both polar and radical stabilization effects play a role in the observed regioselectivities. The application and potential limitations of the analytical method used are discussed.
- Moores, Lee C.,Kaur, Devinder,Smith, Mathew D.,Poole, James S.
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p. 3260 - 3269
(2019/03/11)
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- Synthesis of o-Aryloxy Triarylsulfonium Salts via Aryne Insertion into Diaryl Sulfoxides
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The aryne insertion into "S-O" bond has been validated recently. This technology is elusively applied to the synthesis of thioethers. In contrast to the reported cases, the reaction described furnished o-aryloxy triarylsulfonium salts, in lieu of thioethe
- Li, Xiaojin,Sun, Yan,Huang, Xin,Zhang, Lei,Kong, Lichun,Peng, Bo
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supporting information
p. 838 - 841
(2017/02/26)
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- Total Syntheses of Aporphine Alkaloids via Benzyne Chemistry: An Approach to the Formation of Aporphine Cores
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Total syntheses of lysicamine, (±)-nuciferine, (±)-nornuciferine, (±)-zanthoxyphylline iodide, (±)-O-methylisothebaine, and (±)-trimethoxynoraporphine were accomplished by an approach that involves the formation of aporphine cores through reactions betwee
- Rossini, Allan F. C.,Muraca, Ana Carolina A.,Casagrande, Gleison A.,Raminelli, Cristiano
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p. 10033 - 10040
(2015/11/03)
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- Catalyst-free silylation of alcohols and phenols by promoting HMDS in CH3NO2 as solvent
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An uncatalyzed method for the silylation of alcohols and phenols with HMDS in CH3NO2 at rt is developed. A diverse range of aromatic and aliphatic alcohols as well as phenols undergo the silylation in very short reaction time with ex
- Kadam, Santosh T.,Kim, Sung Soo
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supporting information; experimental part
p. 94 - 98
(2010/05/18)
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- Nafion SAC-13: heterogeneous and reusable catalyst for the activation of HMDS for efficient and selective O-silylation reactions under solvent-free condition
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Nafion SAC-13 effectively activates hexamethyldisilazane (HMDS) for the efficient and selective silylation of alcohols. Primary, secondary, and tertiary alcohols and phenols are efficiently converted to their corresponding silylethers in short reaction ti
- Rajagopal, Gurusamy,Lee, Hanbin,Kim, Sung Soo
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experimental part
p. 4735 - 4741
(2009/10/09)
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- Mild and efficient silylation of alcohols and phenols with HMDS using Bi(OTf)3 under solvent-free condition
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A very efficient and mild silylation of alcohols and phenols with hexamethyldisilazane (HMDS) at rt is developed using Bi(OTf)3 as the catalyst. Primary, secondary and tertiary alcohols as well as phenols are excellently converted into correspo
- Kadam, Santosh T.,Kim, Sung Soo
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experimental part
p. 2562 - 2566
(2009/12/24)
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- Simple and practical protocol for the silylation of phenol derivatives using reusable NaHSO4 dispread on silica gel under neutral conditions
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A simple and mild procedure for the trimethylsilylation of a wide variety of phenols with hexamethyldisilazane (HMDS) on the surface of silica gel dispersed with NaHSO4 at r.t. in a few minutes with excellent yields under neutral conditions is
- Khalili, Mahideh S.,Ghafuri, Hossein,Mojahedi-Jahromi, Samaneh,Hashemi, Mohammed M.
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p. 175 - 179
(2007/10/03)
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- Silica sulfuric acid as a reusable catalyst for efficient and simple silylation of hydroxyl groups using hexamethyldisilazane (HMDS)
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At room temperature, alcohols and phenols are efficiently protected with hexamethyldisilazane (HMDS) in the presence of silica sulfuric acid in good to excellent yields. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. Copyright Taylor and Francis Group, LLC.
- Ghafuri, Hossein,Eftekhari-Sis, Bagher,Hashemi, Mohammed M.
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p. 1645 - 1651
(2008/02/08)
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- Electrophilic Hydroxylation with Bis(trimethylsilyl)peroxide. A Synthon for the Hydroxyl Cation
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The regiospecific introduction of an hydroxy group in aromatic and aliphatic compounds can be performed in good yields by electrophilic hydroxylation of their organometallic derivatives with bis(trimethylsilyl)peroxide.
- Taddei, Maurizio,Ricci, Alfredo
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p. 633 - 635
(2007/10/02)
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- Fragmentation of Trimethylsilyl Derivatives of 2-Alkoxyphenols: a Further Violation of the 'Even-electron Rule'
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The mass spectra of trimethylsilyl (TMS) ethers of 2-methoxyphenols show abundant +* ions originating from consecutive loss of two methyl radicals.This is illustrated by comparison of the accurate mass-measured and linked-scan spectra of the TMS derivatives of 2-methoxyphenol (guaiacol), 4-hydroxy-3-methoxybenzaldehyde (vanillin) and 3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid methyl ester (ferulic acid methyl ester) with those of the TMS derivatives of phenol, 4-hydroxybenzaldehyde, 3-(4-hydroxyphenyl)-2-propenoic acid methyl ester (p-coumaric acid methyl ester), 3-methoxyphenol and 4-methoxyphenol.This distinctive ortho effect is valuable in the identification of isomeric phenolic compounds.In the spectra of the TMS derivatives of 2-ethoxyphenol and 2-propoxyphenol the sequential loss of two radicals is less pronounced, because elimination of the side-chain and methyl group with rearrengement and hydrogen migration is competitive.
- Krauss, Dietlinde,Mainx, Hans Georg,Tauscher, Bernhard,Bischof, Peter
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p. 614 - 618
(2007/10/02)
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