- Oxidation of Phenols and Hydroquinones by Dioxygen Catalyzed by Mixed Addenda Heteropolyoxometalate on Active Carbon (NPV6Mo6/C)
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Vanadomolybdophosphate supported on active carbon, NPV6Mo6/C, catalyzed the oxidation and coupling reaction of 2,3,6-trimethylphenol by dioxygen to give trimethyl-p-benzoquinone and 4,4'-dihydroxy-2,2',3,3',5,5'-hexamethylbiphenyl, respectively, depending on the solvent used.Hydroquinones and benzyl alcohol were selectively dehydrogenated by the present system, giving the corresponding p-benzoquinones and benzaldehyde, respectively, in good yields.
- Fujibayashi, Shinya,Nakayama, Kouichi,Nishiyama, Yutaka,Ishii, Yasutaka
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- Mechanistic and steric issues in the oxidation of phenolic and non-phenolic compounds by laccase or laccase-mediator systems. the case of bifunctional substrates
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Steric and redox issues of phenolic and non-phenolic substrates are investigated for a better insight of the reactivity features of the phenoloxidase laccase. Whenever a substrate is endowed with a redox potential too high for direct monoelectronic oxidation by the enzyme, or else is too much encumbered to access the enzymatic pocket, redox mediators overcome the problem, behaving as an interface between enzyme and substrate. For example, the small-sized mediator ABTS, once oxidised by laccase, fruitfully interacts with bulky substrates, 2,4,6-tri(But)-phenol providing a significant case. Other mediators, for example HBT, resort to a radical oxidation mechanism precluded to laccase, and can react with non-phenolic substrates which are impossible for the enzyme. The advantages provided by the mediators are discussed, and suitable phenolic compounds, as precursors of phenoxyl radical intermediates, emerge as a new proficient class. They could be the true natural mediators of laccase in the oxidative delignification. In fact, phenoxyl radical fragments generated by laccase from lignin, or from phenolic monomer residuals from the building up of lignin polymer or else deriving from lignin by oxidation with other ligninolytic enzymes, could oxidise non-phenolic residues of lignin thereby causing the breakdown of its alkyl network. The novel mechanistic probe 3,5-di(But)-4-OH-benzyl alcohol enables the decoupling of the reactivity channels of a phenolic vs. a benzylic alcohol moiety in the enzymatic oxidation of bifunctional substrates having structural features comparable to portions of lignin. Experimental support is thereby attained for the central role of laccase in biodelignification, in spite of the seemingly lower oxidation power of this enzyme with respect to other and stronger oxidising enzymes excreted by ligninolytic fungi. the Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2006.
- D'Acunzo, Francesca,Galli, Carlo,Gentili, Patrizia,Sergi, Federica
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- Barium manganate oxidation in organic synthesis: Part - V: Oxidation of phenols
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Oxidation of phenols, specially the hindered phenols has been carried out with barium manganate in non-aqueous media under heterogeneous conditions and the results of these studies are described in this paper.
- Srivastava,Venkataramani
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- High diastereoselective [4 + 2] annulation of β,γ-unsaturated α-keto esters and p-quinone methides: Approach to polysubstituted 4-aryl chromans and tetrahydroquinolines
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DBU-mediated [4 + 2] annulation of β,γ-unsaturated α-keto esters and p-quinone methides has been developed. Under mild conditions, the reaction afforded polysubstituted 4-aryl chromans and tetrahydroquinolines as single diastereoisomer in high yields (up
- Si, Wen,Xu, Fan,Liu, Zhanxu,Song, Ran,Lv, Jian
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- 5-Aryl-2-(3,5-dialkyl-4-hydroxyphenyl)-4,4-dimethyl- 4H-imidazole 3-oxides and their redox species: How antioxidant activity of 1-hydroxy-2,5-dihydro- 1h-imidazoles correlates with the stability of hybrid phenoxyl-nitroxides
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Cyclic nitrones of the imidazole series, containing a sterically hindered phenol group, are promising objects for studying antioxidant activity; on the other hand, they can form persistent hybrid phenoxyl-nitroxyl radicals (HPNs) upon oxidation. Here, a series of 5-aryl-4,4-dimethyl- 4H-imidazole 3-oxides was obtained by condensation of aromatic 2-hydroxylaminoketones with 4-formyl-2,6-dialkylphenols followed by oxidation of the initially formed N-hydroxy derivatives. It was shown that the antioxidant activity of both 1-hydroxy-2,5-dihydroimidazoles and 4H-imidazole 3-oxides increases with a decrease in steric volume of the alkyl substituent in the phenol group, while the stability of the corresponding HPNs generated from 4H-imidazole 3-oxides reveals the opposite tendency.
- Amitina, Svetlana A.,Artamonov, Ilya A.,Dmitrieva, Natalya A.,Kandalintseva, Natalya V.,Lomanovich, Alyona V.,Markov, Alexander F.,Mazhukin, Dmitrii G.,Ten, Yury A.,Zaytseva, Elena V.
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- Highly selective conversion of guaiacol to: Tert -butylphenols in supercritical ethanol over a H2WO4 catalyst
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The conversion of guaiacol is examined at 300 °C in supercritical ethanol over a H2WO4 catalyst. Guaiacol is consumed completely, meanwhile, 16.7% aromatic ethers and 80.0% alkylphenols are obtained. Interestingly, tert-butylphenols are produced mainly with a high selectivity of 71.8%, and the overall selectivity of 2,6-di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenol is as high as 63.7%. The experimental results indicate that catechol and 2-ethoxyphenol are the intermediates. Meanwhile, the WO3 sites play an important role in the conversion of guaiacol and the Br?nsted acid sites on H2WO4 enhance the conversion and favour a high selectivity of the tert-butylphenols. The recycling tests show that the carbon deposition on the catalyst surface, the dehydration and partial reduction of the catalyst itself are responsible for the decay of the H2WO4 catalyst. Finally, the possible reaction pathways proposed involve the transetherification process and the alkylation process during guaiacol conversion.
- Mai, Fuhang,Cui, Kai,Wen, Zhe,Wu, Kai,Yan, Fei,Chen, Mengmeng,Chen, Hong,Li, Yongdan
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p. 2764 - 2771
(2019/02/01)
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- Magnetic nano-structured cobalt-cobalt oxide/nitrogen-doped carbon material as an efficient catalyst for aerobic oxidation of p-cresols
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Efficient aerobic oxidation has been developed for the selective preparation of a sequence of valuable p-hydroxybenzaldehydes from corresponding p-cresols, using a new magnetically separable catalyst of nano-structured cobalt-cobalt oxide/nitrogen-doped carbon (CoOx@CN) material. CoOx@CN showed high activity for the 2-methoxy-4-cresol oxidation to vanillin, giving great yield (90%) and with good turnover number (210), as well as other p-cresols in good to great yields. The catalytic performance was investigated and related to the structural, chemical and magnetic properties which determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The effects of base to substrate molar ratio, catalyst concentration, temperature, and solvent on the conversion and selectivity patterns also have been studied. The investigation revealed that remarkable catalytic properties of CoOx@CN could be ascribed to the active species cobalt oxide, doped nitrogen and porous carbon with large surface area. The size of the catalyst is a key factor for catalyst performance. The ferromagnetic property of catalyst enables to recycle easily by an external magnetic field and reuse six successive times without significant activity loss.
- Liang, Cheng,Li, Xuefeng,Su, Diefeng,Ma, Qiyi,Mao, Jianyong,Chen, Zhirong,Wang, Yong,Yao, Jia,Li, Haoran
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p. 121 - 131
(2018/05/22)
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- Preparation method of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol
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The invention discloses a preparation method of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol and belongs to the technical field of organic synthesis. In the technical scheme, a reaction is carried out to 2,6-di-tert-butyl-phenol and a Vilsmeier reagent in a non-protonic solvent at 60-80 DEG C to generate 3,5-di-tert-butyl-4-hydroxybenzaldehyde; and then the 3,5-di-tert-butyl-4-hydroxybenzaldehyde is reacted with a strong-protonic reducing agent to generate the target product, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol. The method is free of special catalyst and is free of gas in the reactions, is high in reaction yield, and is free of complex product post-treatment step, so that the method has wide application prospect.
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Paragraph 0015
(2017/08/30)
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- The cooperative FeCl3/DDQ system for the regioselective synthesis of 3-arylindoles from β-monosubstituted 2-alkenylanilines
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A highly regioselective synthesis of 3-arylindoles by using the cooperative FeCl3/DDQ system has been developed. This new protocol represents an attractive route for the synthesis of 3-arylindoles from readily accessible non-indole precursors, β-aryl-substituted 2-styrylanilines, using an inexpensive catalyst and oxidant. Noteworthy is the unique synergetic and synergistic effect of FeCl3 and DDQ on the 1,2-aryl migratory process.
- Jang, Su San,Youn, So Won
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supporting information
p. 2200 - 2204
(2016/03/01)
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- Environmentally friendly and highly efficient Co(OAc)2-catalyzed aerobic oxidation to access 2,6-di-electron-donating group substituted 4-hydroxybenzaldehydes
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A highly efficient and green aerobic oxidation has been developed for selectively preparing a series of valuable 2,6-dialkyl-, dialkoxyl-, and alkoxylalkyl-substituted 4-hydroxybenzaldehydes from corresponding 4-cresols in good to excellent yields, using a catalytic system of Co(OAc)24H2O (1.0 mol%)-NaOH (1.0 equiv)-O2(1.0 atm) in aqueous ethylene glycol (EG/H2O = 20/1, v/v) at 50 °C. Furthermore, a plausible mechanism was proposed for the direct oxyfunctionalization of the aromatic methyl group into the aldehyde group.
- Jiang, Jian-An,Du, Jia-Lei,Zhang, Zhong-Nan,Zhai, Jiao-Jiao,Ji, Ya-Fei
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supporting information
p. 1430 - 1440
(2016/09/23)
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- Cu(OAc)2-catalyzed remote benzylic C(sp3)-H oxyfunctionalization for C=O formation directed by the hindered para-hydroxyl group with ambient air as the terminal oxidant under ligand- and additive-free conditions
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A hindered para-hydroxyl group-directed remote benzylic C(sp3)-H oxyfunctionalization has been developed for the straightforward transformation of 2,6-disubstituted 4-cresols, 4-alkylphenols, 4-hydroxybenzyl alcohols and 4-hydroxybenzyl alkyl ethers into various aromatic carbonyl compounds. The ligand- and additive-free Cu(OAc)2-catalyzed atmospheric oxidation mediated by ethylene glycol unlocks a facile, atom-economical, and environmentally benign C=O formation for the functionalization of primary and secondary benzyl groups. Due to the pharmaceutical importance of 4-hydroxybenzaldehydes and 4-hydroxyphenones, the methodology is expected to be of significant value for both fundamental research and practical applications.
- Jiang, Jian-An,Chen, Cheng,Huang, Jian-Gang,Liu, Hong-Wei,Cao, Song,Ji, Ya-Fei
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supporting information
p. 1248 - 1254
(2014/03/21)
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- Metal-free C-H amination for indole synthesis
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An effective metal-free C-H amination of N-Ts-2-alkenylanilines by using DDQ as an oxidant has been developed to afford a diverse range of substituted indoles. This protocol is operationally simple and robust, obviates the need of expensive transition-metal catalysts, and offers a broad substrate scope. A mechanism involving a radical cation generated by SET and a migratorial process via a phenonium ion intermediate is proposed.
- Jang, Young Ho,Youn, So Won
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supporting information
p. 3720 - 3723
(2014/08/05)
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- Synthesis and oxidizing ability of p-chloranil dimer
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A p-chloranil dimer ( pCh2) has been synthesized. The first reduction potential of pCh2 shifted to a more positive value than that observed for the p-chloranil monomer ( pCh1) and was more negative than that for 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). As expected, pCh2 oxidized 9,10-dihydroanthracene and α-tetralol to give anthracene and α-tetralone, respectively, more efficiently than pCh1 did. The advantages of pCh2 were observed in oxidations of 2,4-di-tert-butylphenol and 2,6-di-tertbutyl- 4-methylphenol. Although further oxidation took place in DDQ oxidations and no reaction occurred in pCh1 oxidations, initial oxidation products were solely obtained in pCh2 oxidation because of its moderate oxidizing ability.
- Hayashi, Naoto,Nakagawa, Hiroyuki,Sugiyama, Yuko,Yoshino, Junro,Higuchi, Hiroyuki
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p. 398 - 400
(2013/05/21)
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- Solvolysis of 4-halogeno-4-alkyl-2,6-di-tert-butylcyclohexa-2,5-dienones induced by positive halogen donors as electrophiles
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Positive halogen donors such as N-iodosuccinimide (NIS) induce solvolysis of dienones 1, as model 4-halogenocyclohexa-2,5-dienones, in different hydroxylic solvents (ROH), yielding the 4-RO-cyclohexa-2,5-dienones (2). The rate of the solvolysis with NIS is highly dependent on the structure of ROH. The problem of such dependency is overcome by running the reaction in ROH diluted with MeCN, a polar aprotic solvent, in place of pure ROH; the rate of the reaction in the ROH-MeCN solvent mixture is almost independent of the structure (or the polarity) of ROH, and the reaction is completed faster or markedly faster than in neat ROH. The results suggest that the solvolysis rate is controlled by the polarity of the solvent system, although the hydrogen-bond acceptability of MeCN for dilution also accelerates the reaction. A mechanism for the solvolysis is proposed, involving electrophilic attack of a positive halogen donor at the halogen atom of 1, generating the 4-oxocyclohexa-2,5-dienyl cation intermediates (8) via the rate-limiting polar transition states. CSIRO 2013.
- Omura, Kanji
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p. 1386 - 1392
(2013/12/04)
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- Peroxy radical activated addition of tert-butylcatechol to 2,6-Di-tert-butyl-7-substituted quinone methide polymerization retarders
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Peroxy radicals formed by the autoxidation of styrene react with 4-tert-butylcatechol (TBC) to give a tert-butyl-semiquinone radical. When the TBC radical is generated in the presence of a 2,6-di-tert-butyl-7-substituted quinone methide (QM), the result is o-TBC addition at the 7-position of the QM. The effects of TBC/QM addition are observed during styrene polymerization retarder testing under aerobic conditions for 2-(3,5-di-tert-butyl-4- oxocyclohexa-2,5-dien-1-ylidene)acetonitrile (QM-CN), 2,6-di-tert-butyl-4- (methoxymethylene)cyclohexa-2,5-dienone (QM-OMe), and 4-benzylidene-2,6-di-tert- butylcyclohexa-2,5-dienone (QM-Ph). Increasing the concentrations of QM-Ph and TBC during aerobic batch styrene polymerization allowed for silica gel chromatography isolation of 5-(tert-butyl)-3-((3,5-di-tert-butyl-4- hydroxyphenyl)(phenyl)methyl)benzene-1,2-diol, a novel compound. Radicals generated by the autoxidation of cumene and by homolysis of dicumylperoxide also activate TBC/QM addition. TBC/QM interaction causes a reduction in the performance of QMs as styrene polymerization retarders under aerobic conditions. Under anaerobic test conditions, a better simulation of industrial styrene purification, the TBC/QM interaction leads to only minimal reduction in retarder performance.
- Neilson, Andrew R.,Morrison, Christopher F.
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body text
p. 65 - 69
(2012/05/31)
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- 3,5-Di-tert-butyl-4-hydroxybenzaldehyde derivatives as antioxidants in cumene oxidation
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A series of 4-hydroxy-3,5-di-tert-butylbenzaldehyde derivatives were prepared, and their antioxidant properties were studied.
- Magerramov,Askerova,Mamedov,Rzaeva,Allakhverdiev
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experimental part
p. 644 - 650
(2012/08/08)
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- PROCESS FOR PREPARING SUBSTITUTED 1,4-QUINONE METHIDES
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A method for preparing a substituted 1,4-quinone methide from a 3,5-disubstituted 4-hydroxybenzaldehyde is provided. Also provided is a method to prepare a 3,5-disubstituted 4-hydroxybenzaldehyde from the corresponding 2,6-disubstituted phenol.
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Page/Page column 8; 9
(2010/11/03)
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- Electron transfer between protonated and unprotonated phenoxyl radicals
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(Chemical Equation Presented) The reaction of phenoxyl radicals with acids is investigated. 2,4,6-Tri-tert-butylphenoxyl radical (13), a persistent radical, deteriorates in MeOH/PhH in the presence of an acid yielding 4-methoxycyclohexa-2,5-dienone 18a and the parent phenol (14). The reaction is facilitated by a strong acid. Treatment of 2,6-di-tert-butyl-4-methylphenoxyl radical (2), a short-lived radical, generated by dissociation of its dimer, with an acid in MeOH provides 4-methoxycyclohexa-2,5-dienone 4 and the products from disproportionation of 2 including the parent phenol (3). A strong acid in a high concentration favors the formation of 4 while the yield of 3 is always kept high. Oxidation of the parent phenol (33) with PbO2 to generate transient 2,6-di-tert-butylphenoxyl radical (35) in AcOH/H2O containing an added acid provides eventually p-benzoquinone 39 and 4,4′-diphenoquinone 42, the product from dimerization of 35. A strong acid in a high concentration favors the formation of 39. These results suggest that a phenoxyl radical is protonated by an acid and electron transfer takes place from another phenoxyl radical to the protonated phenoxyl radical, thus generating the phenoxyl cation, which can add an oxygen nucleophile, and the phenol (eq 5). The electron transfer is a fast reaction.
- Omura, Kanji
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p. 858 - 867
(2008/09/19)
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- Synthesis and evaluation of the anti-inflammatory activity of N-[2-(3,5-di-tert-butyl-4-hydroxyphenyl)-4-oxothiazolidin-3-yl]-nicotinamide
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A new molecule incorporating nicotinoyl moiety, thiazolidin-4-one ring and 3,5-di-tert-butyl-4-hydroxyphenyl group (a potent antioxidant moiety) was synthesized and evaluated for anti-inflammatory activity in acute as well as chronic phase models of inflammation. The compound exhibited significant anti-inflammatory activity in three experimental models of inflammation, comparable to the positive control drug, ibuprofen (CAS 15687-27-1). It is suggested that besides the hypolipidemic and antioxidant potential of the molecule, its anti-inflammatory action could possibly act as an additional mechanism of its hypothesized anti-atherosclerotic activity. ECV Editio Cantor Verlag.
- Kalia, Rajiv,Rao, Chamallamudi Mallikarjuna,Gopalan Kutty, Nampurath
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p. 616 - 622
(2008/03/13)
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- Total synthesis of (±)-quadrangularin A
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The key to successful coupling in the synthesis of (±)- quadrangularin A (1) was the introduction of tert-butyl groups in the precursor to block two reactive positions. Thus, the oxidative coupling of 3,5-di-(tert-butyl) resveratrol was carried out regioselectively in an efficient total synthesis of the natural product. (Chemical Equation Presented)
- Li, Wenling,Li, Hao,Li, Ying,Hou, Zijie
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p. 7609 - 7611
(2008/02/12)
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- Selective oxidation of benzylic alcohols and TBDMS ethers to carbonyl compounds with CrO3-H5IO6
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Benzyl alcohols and benzyl TBDMS ethers were efficiently oxidized to the corresponding carbonyl compounds in high yield with periodic acid catalyzed by CrO3 at low temperature (-78°C). The oxidation procedure was highly functional group tolerant and very selective for the TBDMS group over the TBDPS group. Georg Thieme Verlag Stuttgart.
- Zhang, Suhong,Xu, Liang,Trudell, Mark L.
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p. 1757 - 1760
(2007/10/03)
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- Synthesis and characterization of BHT-derived tert-butyl dendrons
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(Chemical Equation Presented) A series of 3,5-poly(aryl ether) dendrons was prepared up to the third generation using inexpensive 3,5-di-tert-butyl-4- hydroxytoluene (BHT, 1) as a starting material.
- Shanahan, Charles S.,McGrath, Dominic V.
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p. 1054 - 1056
(2007/10/03)
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- A stabilized formulation of IBX (SIBX) for safe oxidation reactions including a new oxidative demethylation of phenolic methyl aryl ethers
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(Matrix presented) SIBX is a nonexplosive formulation of IBX that can be used as a suspension in a variety of standard organic solvents such as refluxing EtOAc and THF to oxidize safely alcohols into aldehydes and ketones. The use of hot THF is limited to the oxidation of allylic and benzylic alcohols. Most yields are comparable to those obtained with IBX or DMP. SIBX can also be used to perform oxygenative demethylation of 2-methoxyarenols into orthoquinones and catechols.
- Ozanne, Aurelie,Pouysegu, Laurent,Depernet, Dominique,Francois, Bruno,Quideau, Stephane
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p. 2903 - 2906
(2007/10/03)
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- Bi0-catalyzed oxidation of mandelic acid derivatives: Substrate selectivity
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A series of mandelic acid derivatives was oxidized with a bismuth-catalyzed oxidation system based on Bi0/DMSO/O2. Benzaldehyde and/or benzoic acid derivatives could be obtained chemoselectively depending on the catalytic system and the substitution on the aromatic ring. A strong substrate selectivity was observed, suggesting different oxidation mechanisms. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Favier, Isabel,Giulieri, Francoise,Dunach, Elisabet,Hebrault, Dominique,Desmurs, Jean-Roger
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p. 1984 - 1988
(2007/10/03)
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- NBS-Promoted Reactions of Symmetrically Hindered Methylphenols via p-Benzoquinone Methide
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Symmetrically hindered methylphenols 1 react smoothly with NBS to form transient intermediates, p-benzoquinone methides (BM), which can be further processed to give hydroxybenzaldehydes in the presence of DMSO. This reaction is initiated by the formation of the phenoxy radical, followed by disproportionation to afford BM. None of the side-chain-brominated product is observed. The existence of BM is supported by the following observations: the formation of BM in solution can be monitored by GC and GC-MS; the electrophilic methine part participates in electrophilic aromatic substitution with anisoles to give hydroxybenzylated products 15; and the double bond character of the exocyclic methine plays a role in [4 + 2] cycloaddition with diene to afford Diels-Alder adducts. In contrast, unsymmetrically hindered or simple methylphenol (p-cresol) with NBS gives the nuclear brominated products, as usual. The energies of symmetrically hindered BMs, unsymmetrically hindered BM, and simple BM were calculated using density functional theories. Relative stabilization energies calculated at the B3LYP/6-31G*//B3LYP/6-31G* level by an isodesmic equation are enhanced 3-6 kcal/mol for symmetrically hindered BMs.
- Baik, Woonphil,Lee, Hyun Joo,Jang, Jung Min,Koo, Sangho,Kim, Byeong Hyo
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p. 108 - 115
(2007/10/03)
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- Ozonation of 1,1,2,2-tetraphenylethene revisited: Evidence for electron- transfer oxygenations
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Ozonolyses of 1,1,2,2-tetraphenylethene (TPE, 1) have been described many times in the literature, but the reports are contradictory. This reaction is particularly important for understanding the mechanism of alkene ozonolysis, in view of possible stabilization of reactive intermediates by aryl groups. Thus, systematic investigations of ozonolysis in both aprotic solvents and in protic solvents are reported here. Attention is directed to the following details that have been underestimated in the past: i) the actual electronic structure of ground-state ozone (O3), ii) differentiation between strained and unstrained alkenes, iii) the significance of both the O3 concentration and the TPE concentration, iv) the influence of various solvents, including pyridine, v) the influence of the reaction temperature, vi) the role of electron-transfer catalysis (ETC) and, yii) the effect of structural modifications. Our results suggest that ozonolysis of TPE (1) does not include a 1,3-dipolar reaction step, but represents a particularly interesting example of electron-donor (TPE)/electron-acceptor (O3) redox chemistry. The present investigations include several crucial results. First, pure 3,3,6,6-tetraphenyltetroxane (3, m.p. 221°(dec.)) and pure tetraphenylethylene ozonide (4, m.p. 153°(dec.)) are prepared for the first time, although 3 and 4 have long been known. Second, the singlet diradical character of O3, lessened by means of hypervalent-electron interaction and predicted by different calculations, is evidenced via reaction with the spintrap galvinoxyl (2,6-bis(1-1-dimethylethyl)-4-{[3,5-bis(1,1- dimethylethyl)-4-oxocyclohexa-2,5-dien-1-ylidene]methyl}phenoxy; 8), and the zwitterionic reaction behavior of ground-state O3 is ruled out. Third, the electronacceptor ability of O3 is evidenced by reactions with suitable tetraaryl ethylenes: it is enhanced by addition of catalytic amounts of protons or Lewis acids. Fourth, the observed distribution of the O3 O-atoms to the two different olefinic C-atoms of the unsymmetric alkene 27b is in full agreement with an initial single-electron transfer (SET) step, followed by a radical mono-oxygenation to cause the crucial C,C cleavage. Final dioxygenation should lead to the generally known products (ozonides, tetroxanes, hydroperoxides). The regioselectivity is found to be inconsistent with the expected decay of an intermediate primary ozonide. Finally, the treatment of 1,2-bis(4-methoxyphenyl)acenaphthylene (36) with O3 (simultaneous transfer of three O-atoms) leads to the same experimental result as a stepwise transfer of one O-atom followed by a transfer of two O- atoms.
- Schank, Kurt,Beck, Horst,Buschlinger, Michael,Eder, Joerg,Heisel, Thomas,Pistorius, Susanne,Wagner, Christiane
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p. 801 - 826
(2007/10/03)
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- Thermal decomposition of 2,6-di-tert-butyl-4-dimethylaminomethylphenol
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Products of thermolysis of 2,6-di-tert-butyl-4-dimethylaminomethylphenol were determined qualitatively and quantitatively by GLC, UV, and 1H NMR methods. The kinetics of the reaction was studied. The thermolysis products were studied as the inhibitors in thermopolymerization of monomers.
- Zakharova,Khismatullina,Ivanov
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p. 1787 - 1789
(2007/10/03)
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- Reactivity of 3,5-di-tert-butyl-4-hydroxybenzaldehyde, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and (3,5-di-tert-butyl-4-hydroxybenzyl)methyl ether at oxidation by oxygen in basic solutions
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Reactivity at oxidation in basic water-ethanol solutions of the fallowing phenols: 3,5-di-tert-butyl-4-hydroxybenzaldehyde, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, and (3,5-di-tert-butyl-4-hydroxybenzyl)methyl ether was studied as affected by α-located oxygen-containing functional groups and the base nature. It is shown that the substrate reactivity drops in the order: alcohol ≥ ether > aldehyde. In the presence of NaOH, Na2CO3, and NaHCO3 the alcohol and the ether are similar in efficiency, while in aqueous ammonia the alcohol reactivity is much higher than that of ether. Aldehyde oxidizes in ammoniak with the tenfold faster than in solutions of NaOH, Na2CO3, and NaHCO3.
- Fedulina,Klindukhov
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p. 692 - 698
(2007/10/03)
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- Oxidative Dehydrogenation of Sterically Hindered para-Substituted Phenols with 3,3′,5,5′-Tetra-tert-butyl-4,4′-diphenoquinone
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The reactivity of 4-methyl-, 4-mercapto-, and 4-methoxymethyl-2,6-di-tert-butylphenols in oxidative dehydrogenation with 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone was studied, and the structure of products was determined.
- Mukmeneva,Bukharov,Kadyrova,Zharkova,Gorshunova,Fazlieva
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p. 1486 - 1489
(2007/10/03)
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- Antiviral use of a 2,6-di-t-butylphenol compound substituted in 4 position against herpes viruses and papillomaviruses
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A therapeutical use is provided for cornpounds selected from the group which consists of (a) phenols of formula (I): STR1 wherein R is a C1-12 alkyl group, a C2-12 alkenyl group, a C2-12 alkynyl group, a C1-12 alkoxy group, a formyl group, a C2-12 alkanoyl group, a C1-12 hydroxyalkyl group, a primary, secondary or tertiary amide group, an OCH3 group, CH2 OH or a COOH group or an A--COOH group where A is a C1-11 aliphatic hydrocarbon residue; and (b) the corresponding salts and esters thereof when R is COOH or A--COOH; for obtaining an antiviral drug for use in the human or veterinary therapeutical treatment of viral diseases.
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- Identification of Degradation Products of Terbutol in Environmental Water from Golf Courses
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Degradation products of terbutol (2,6-di-tert-butyl-4-methylphenyl N-methylcarbamate) in drainage and ground water from golf courses, on which terbutol had been applied as a herbicide, were identified by capillary GC/MS and reversed-phase HPLC. terbutol and 4-carboxy-, N-demethyl-, and 4-carboxy-N-demethylterbutol were detected in all water samples at concentrations of parts per billion levels.In addition, 4-(hydroxymethyl)- and 4-formylterbutol, 2,6-di-tert-butyl-4-methylphenol (BHT), and 4-(hydroxymethyl)-, 4-formyl-, and 4-carboxy-BHT were observed in some water samples at concentrations of parts per thousand levels.These results demonstrated that terbutol applied on golf courses was mainly degraded by N-demethylation, oxidation of the 4-methyl group, and hydrolysis of the carbamate ester linkage. Keywords:Terbutol; 2,6-di-tert-butyl-4-methylphenyl N-methylcarbamate; identification; degradation
- Suzuki, Toshinari,Yaguchi, Kumiko,Ohnishi, Kazuo,Suga, Tetsuya
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p. 1712 - 1717
(2007/10/02)
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- α-SUBSTITUIERTE PHOSPHONATE 71. ZUR REAKTION 7-PHOSPHONOSUBSTITUIERTER CHINONMETHIDE MIT NUCLEOPHILEN
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Quinone methides with one or two phosphono-substituents in 7-position reacts with O-, N-, S- and C-nucleophiles by addition in 7-position.Key words: Arylmethanbisphosphonates; 7-phosphorylated quinonemethides; 31P-, 13C-NMR
- Costisella, Burkhard,Keitel, Iris,Gross, Hans,Nadolski, Karin
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- The Oxidation of 2,4,6-Trimethylphenol with Molecular Oxygen Catalyzed by a Copper(II)-Oxime or Copper(II)-Amine System
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2,4,6-Trimethylphenol (1a) was selectively oxidized to 3,5-dimethyl-4-hydroxybenzaldehyde (2a) by molecular oxygen in the presence of a copper(II) chloride-oxime or copper(II) chloride-amine catalyst in alcohol at ambient temperature.When an acid was present in the catalyst system, the formation of both 2,6-dimethyl-p-benzoquinone (3) and a formaldehyde dialkyl acetal was accelerated.It is likely that 2a is produced by way of the formation of a quinonemethide intermediate, followed by a repeated 1,6-addition of alcohol on the intermediate to form a 4-(alkoxymethyl)-2,6-dimethylphenol (5a), and then 3,5-dimethyl-4-hydroxybenzaldehyde dialkyl acetal, which would be hydrolyzed to 2a.When the reaction time was shortened, 5a was isolated in good yield.Oxidations of the other p-methyl-substituted phenols were also examined using the present oxidation system.
- Shimizu, Masao,Watanabe, Yoshihito,Orita, Hideo,Hayakawa, Takashi,Takehira, Katsuomi
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p. 251 - 257
(2007/10/02)
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- Photochromatic compound, a method for its preparation, and articles which contain it
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A photochromatic compound represented by the following general formula (I): STR1 where: R1 and R2 independently represent a linear, branched or cyclic C1-C10 alkyl radical, H, OH, F, Cl, Br, NH2, N(R4)2, COOH, OR4 or COOR4 where R4 is a C1-C10 linear, branched or cyclic alkyl radical, or an aryl radical; R3 is a variously substituted mono or polycondensed heterocyclic or aryl radical. A compound (I) demonstrates marked photochromatic characteristics both when in an organic solvent solution and when incorporated into polymer matrices.
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- Oxidation Using Quaternary Ammonium Polyhalides. IX. Oxidation of Hindered Phenols with Benzyltrimethylammonium Tribromide
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Reactions of hindered phenols, such as 2,6-di-t-butyl-4-methylphenol, 3,5-di-t-butyl-4-hydroxybenzyl alcohol, and 2,6-di-t-butylphenol, with benzyltrimethylammonium tribromide were carried out in dichloromethane in the presence of water, t-butyl alcohol, or aqueous sodium hydroxide at room temperature.Sequential reaction processes were provided by the obtained products.
- Kajigaeshi, Shoji,Morikawa, Yukihiro,Fujisaki, Shizuo,Kakinami, Takaaki,Nishihira, Keigo
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p. 1060 - 1062
(2007/10/02)
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- Oxidation by Cobalt(III) Acetate. Part 13. Oxidation of Substituted Phenols with Cobalt(III) Acetate in Acetic Acid
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The oxidation of 2,6-di- and 2,4,6-tri-substituted phenols with cobalt(III) acetate has been investigated in acetic acid under an inert atmosphere; the former gave the corresponding diphenoquinones in excellent yields, and the latter yielded side-chain or nuclear acetoxylated products in moderate to good yields.
- Hirano, Masao,Ishii, Tadamichi,Morimoto, Takashi
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p. 1434 - 1436
(2007/10/02)
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- A Facile Synthesis of 4-Alkoxymethylphenols by a Copper(II)-Acetoxime Catalyst/O2 System
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4-Alkoxymethyl-2,6-dimethylphenols were synthesized from 2,4,6-trimethylphenol in good yields by a copper(II) chloride-acetoxime catalyst/molecular oxygen system in alcohols at ambient temperature.The oxidation of the other p-methylsubstituted phenols were also examined.
- Shimizu, Masao,Watanabe, Yoshihito,Orita, Hideo,Hayakawa, Takashi,Takehira, Katsuomi
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p. 2053 - 2056
(2007/10/02)
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- Photochromatic compound, a method for its preparation, and articles which contain it
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A photochromatic compound represented by the following general formula (I): where:, R1 and R2 independently represent a linear, branched or cyclic C1-C10 alkyl radical, H, OH, F, Cl, Br, NH2, N(R4)2, COOH, OR4 or COOR4 where R4 is a C1-C10 linear, branched or cyclic alkyl radical, or an aryl radical;, R3 is a variously substituted mono or polycondensed heterocyclic or aryl radical. A compound (I) demonstrates marked photochromatic characteristics both when in an organic solvent solution and when incorporated into polymer matrices.
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- Process for production of aromatic aldehydes
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Aromatic aldehydes are produced by oxidation with oxygen of a para-cresol derivative in a solvent, in the presence of a base and a catalytic amount of a cobalt compound. The catalyst is a chelated complex of cobalt with a rigid structure that is slightly oxidizable selected from the group consisting of bis-(4-methylpyridine isoindolinato)cobalt(II) acetate, phthalocyaninatocobalt(II), and sulfophthalocyaninanatocobalt(II). The process is particularly suited to the production of p-hydroxy benzaldehydes.
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- OXIDATION OF 3,5-DI-tert-BUTYL-4-HYDROXYBENZYL ALCOHOL AND 3,5-DI-tert-BUTYL-4-HYDROXYBENZALALDEHYDE BY OXYGEN IN AQUEOUS AMMONIUM SOLUTION
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The main reaction products during the oxidation of 3,5-di-tert-butyl-4-hydroxy-benzyl alcohol and 3,5-di-tert-butyl-4-hydroxybenzaldehyde by oxygen in a waterpropanol solution of ammonia are 3,3',5,5'-tetra-tert-butyldiphenoquinone, 2,6-di-tert-butyl-1,4-benzoquinone, and 3,3'5,5'-tetra-tert-butylindophenol, which is formed in the reaction of the above-mentioned p-benzoquinone with ammonia.Three nitrogen containing substances were also found in the products from the oxidative ammonolysis of the aldehyde, i.e., 2,6-di-tert-butyl-4-cyanophenol, 2,6-di-tert-butyl-4--2,5-cyclohexadien-1-one, and a third compound with a molecular mass of 490, for which the elemental composition was determined.
- Fedulina, T. G.,Deineko, I. P.,Klindukhov, V. P.
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p. 1540 - 1548
(2007/10/02)
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- Process for nucleophilic fluoroalkylation of aldehydes
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Aryl difluoromethyl sulfone adds to alkehydes under phase transfer conditions to give novel substituted alcohols of the general formula wherein R is an aryl, cycloaliphatic, sec- or tert-aliphatic, or heterocyclic group and Ar is an aryl group. The substituted alcohols of formula I are of particular utility as intermediates in the synthesis of a variety of useful end products. For example, the products of formula I may be utilized in desulfonylation reactions, oxidation reactions and fluorination reactions.
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- OXYGENATION OF (E)-4-STILBENOLS CATALYSED BY COBALT(II) SCHIFF BASE CHELATES
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Cobalt(II) Schiff base chelate, CoSMDPT (1), catalysed the oxygenation of (E)-4-stilbenols (2a-2d), to give two molecules of aldehydes.Both the oxygen atoms of dioxygen are incorporated into the substrate, providing a good chemical model for dioxygenase reactions.
- Ganeshpure, P. A.,Satish, S.
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p. 6629 - 6632
(2007/10/02)
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- OXIDATION OF 2,6-DI-tert-BUTYL-4-METHYLPHENOL BY OXYGEN IN AQUEOUS AMMONIA SOLUTION
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Both monomeric and dimeric oxidation products are formed during the oxidation of 2,6-di-tert-butyl-4-methylphenol (ionole) by oxygen in a water-propanol solution of ammonia.Two nitrogen-containing compounds 3,3'-5,5'-tetra-tert-butylindophenol and 2,6-di-tert-butyl-4-cyanophenol are also formed, and their amounts in the reaction mixture increase with increase in temperature (45-120 deg C).
- Fedulina, T. G.,Deineko, I. P.,Zenkevich, I. G.,Zarubin, M. Ya.
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p. 1373 - 1377
(2007/10/02)
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- Oxygenation of tert-Butylphenols with an Unsaturated Side Chain
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Base- and Co(Salpr)-promoted oxygenations of title compounds have been investigated with a view to obtaining further details concerning controlling factors in regioselective O2 incorporation into phenols.In the oxygenation of 4-alkenyl-2,6-di-tert-butyl- and 2-alkenyl-4,6-di-tert-butylphenols (1 and 12), the reactivity of the substrates and regioselectivity in the O2 incorporation may be interpreted in terms of electronic and steric effects of the alkenyl group as well as association effect of the countercation K+ on the transition-state 26 involving a charge transfer from the substrate anion to O2.With 4-alkynyl-2,6-di-tert-butylphenols (21), dioxygen was incorporated exclusively into the ortho position only when the phenolate anion was associated with K+.On the contrary, in the oxygenation of 1 and 12 with Co(Salpr), O2 was incorporated exclusively into the alkynyl side chain, regardless of the nature of the substituent, whereas with 21, O2 incorporation was distributed to both the ortho and the alkenyl side chain.The substituent-dependent regioselectivity in the oxygenation of phenols with Co(Salpr) is because the reactive phenolate-COIII species undergo homolysis to form phenoxy radical-CoII species reversibly, whose oxygenations compete with each other.When the oxygenation of the anionic species predominates, O2 is incorporated into the ortho position, whereas with the radical species the para and side chain oxydations predominate.
- Nishinaga, Akira,Iwasaki, Hitoshi,Shimizu, Tadashi,Toyoda, Yasushi,Matsuura, Teru
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p. 2257 - 2266
(2007/10/02)
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- Electrochemical Oxidation of 2,6-Di-tert-butyl-4-methylphenol in Basic Methanol
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Electrochemical oxidation of 2,6-di-tert-butyl-4-methylphenol (1) in methanol containing sodium methoxide gave side-chain-oxidized phenols, ArCH2OMe, ArCHO, and ArCOOMe (Ar=3,5-di-tert-butyl-4-hydroxyphenyl), together with 2,6-di-tert-butylbenzoquinone and 3,5,3',5'-tetra-tert-butyl-4,4'-diphenoquinone.The product distribution varied with the electricity consumption.Based on the results obtained, a simple electrochemical transformation of 1 to the hydroxybenzaldehyde ArCHO was effected.Keywords --- electrochemical oxidation; cyclic voltammetry; controlled potential electrolysis; 2,6-di-tert-butyl-4-methylphenol; 3,5-di-tert-butyl-4-hydroxybenzaldehyde
- Ohmori, Hidenobu,Ueda, Chihiro,Tokuno, Yoshimi,Maeda, Hatsuo,Masui, Masaichiro
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p. 4007 - 4011
(2007/10/02)
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