- Copper-Catalyzed Chemo- and Diastereoselective 1,3-Dipolar Cycloaddition of Carbonyl Ylide and Aldehyde-Tethered-Cyclohexadienone to Access Polycyclic Systems
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A copper-catalyzed tandem intermolecular ylide formation/intramolecular cycloaddition of diazo compounds and aldehyde-tethered-cyclohexadienones was reported, chemo- and diastereoselectively providing oxapolycyclic frameworks in moderate to excellent yields under mild conditions. This reaction creates two C?C bonds and one C?O bond with five stereocentres including two all-carbon quaternary centres. Moreover, the late-stage diversification of products can be realized via chemoselective substitutions. (Figure presented.).
- Peng, Shiyong,Zhang, Hong,Zhu, Yuqi,Zhou, Ting,He, Jieyin,Chen, Nuan,Lang, Ming,Li, Hongguang,Wang, Jian
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supporting information
p. 4532 - 4537
(2021/08/09)
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- Site-selective 1,3-double functionalization of arenes using: Para -quinol, C-N, and C-C/C-P three-component coupling
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A catalytic and site-selective approach has been demonstrated for dual functionalization of arenes via cross-coupling reactions of p-quinols with amines and isocyanides/phosphites. The strategy enables the production of a series of 3-amino-benzamides and
- Husen, Saddam,Chauhan, Anil,Kumar, Ravindra
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supporting information
p. 1119 - 1124
(2020/03/11)
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- Zinc-catalyzed regioselective C-P coupling of p-quinol ethers with secondary phosphine oxides to afford 2-phosphinylphenols
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The zinc triflate-catalyzed highly regioselective C-P cross coupling reaction of p-quinol ethers with secondary phosphine oxides is reported. The reaction provides a facile alternative method for the synthesis of 2-phosphinylphenols in good to high yields. Mechanistically, zinc triflate may serve as an oxophilic σ-Lewis acid to activate the C-O bond in p-quinol ether first. Then the regioselective attack of the phosphorus nucleophile at the α-carbon position takes place to form the C-P bond and give the product. In addition, α-alkynyl substituted p-quinol ethers also react with secondary phosphine oxides in the same reaction mode to give 6-alkynyl 2-phosphinylphenols in the presence of the zinc catalyst.
- Zhang, Ming,Jia, Xiaoyu,Zhu, Haowei,Fang, Xutong,Ji, Chenyi,Zhao, Sizhuo,Han, Li-Biao,Shen, Ruwei
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p. 2972 - 2984
(2019/03/21)
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- Experimental evidence for the formation of cationic intermediates during iodine(iii)-mediated oxidative dearomatization of phenols
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Iodine(iii)-based oxidants are commonly used reagents for the oxidative dearomatization of phenols. Having a better understanding of the mechanism through which these reactions proceed is important for designing new iodine(iii)-based reagents, catalysts, and reactions. We have performed a Hammett analysis of the oxidative dearomatization of substituted 4-phenylphenols. This study confirms that iodine(iii)-mediated oxidative dearomatizations likely proceed through cationic phenoxenium ions and not the direct addition of a nucleophile to an iodine-bound phenol intermediate.
- Tang, Ting,Harned, Andrew M.
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supporting information
p. 6871 - 6874
(2018/10/02)
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- Iodobenzene and m-chloroperbenzoic acid mediated oxidative dearomatization of phenols
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Oxidative dearomatization of 2- and 4-substituted phenols to their corresponding benzoquinone monoketals by catalytic amount of iodobenzene, and m-CPBA as a co-oxidant has been achieved via in situ generation of PhIO2, a hypervalent iodine(V) s
- Taneja, Neha,Peddinti, Rama Krishna
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p. 3958 - 3963
(2016/08/11)
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- Site-Selective Iron(III) Chloride-Catalyzed Arylation of 4-Aryl-4-methoxy-2,5-cyclohexadienones for the Synthesis of Polyarylated Phenols
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The iron(III) chloride-catalyzed Friedel–Crafts arylation of 4-aryl-4-methoxy-2,5-cyclohexadienones, which were easily prepared by the phenyliodine(III) diacetate (PIDA)-mediated oxidation of 4-arylphenols in methanol, proceeded site-selectively to form meta-terphenyl (2,4-diarylphenol) derivatives in good yields. The subsequent PIDA-mediated oxidation and iron(III) chloride-catalyzed Friedel–Crafts arylation of the resulting products gave the corresponding 2,4,6-triarylphenol derivatives. The present method provides useful highly substituted polyarylated compounds. (Figure presented.).
- Sawama, Yoshinari,Masuda, Masahiro,Nakatani, Ryosuke,Yokoyama, Hiroki,Monguchi, Yasunari,Dohi, Toshifumi,Kita, Yasuyuki,Sajiki, Hironao
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supporting information
p. 3683 - 3687
(2016/12/16)
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- Meta-selective substitution of phenols with indoles via one-pot oxidative dearomatization-Michael addition-aromatization
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An oxidative coupling strategy involving hypervalent organoiodine-induced oxidative dearomatization of 4-substituted phenols, Br?nsted acid catalyzed Michael addition with indoles, and aromatization has been developed. The one-pot reaction provides an eff
- Ye, Yang,Wang, Hua,Fan, Renhua
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supporting information; experimental part
p. 923 - 926
(2011/06/17)
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- Oxidation with hypervalent iodine reagents. Part II: Novel cyclohexadienones as precursors for the synthesis of anthraquinones
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The oxidation of substituted phenols with phenyliodonium diacetate in methanol was found to afford 2,4-cyclohexadienones, 2,5-cyclohexadienones or mixtures of isomers, depending on the substrate being oxidized. Annulation of these cyclohexadienones with the anion of 3-cyanophthalide afforded anthraquinones in high yields.
- Mitchell, Anthony S.,Russell, Richard A.
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p. 4387 - 4410
(2007/10/03)
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- The Electrochemical Preparation and Kinetic and Product Studies of Acylated Quinol and Quinol Ether Imines. In Search of the Hydrolysis Products of the "Ultimate" Carcinogen of N-Acetyl-2-aminofluorene
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The N-acetyl and benzoyl derivatives of 4-methoxy-4-phenyl-2,5-cyclohexadienone imine and the N-benzoyl derivative of 4-hydroxy-4-phenyl-2,5-cyclohexadienone imine (1a-c) have been prepared via anodic oxidation of the corresponding amide of 4-aminobiphenyl in either methanol or water/ acetonitrile, respectively.The products and the kinetics of the acidic and basic hydrolyses of these compounds were studied and the results compared with other N-acylquinol imine derivatives, including N-acetyl-4-hydroxy-4-phenyl-2,5-cyclohexadienone imine (1d), generated by solvolytic routes.The chemistry of these compounds was dependent upon the pH and the substituents on the quinol imine derivative.The major reaction pathways were hydrolysis of the imine linkage to afford the respective dienone and phenyl migration to afford the amides of 2-hydroxy- or 2-methoxy-5-aminobiphenyl.The reactivity of the quinol imine derivatives follows the order: 4-hydroxyl more reactive than 4-methoxyl compounds and N-acetyl more reactive than N-benzoyl derivatives.The higher reactivity for the former compounds is attributed to the greater electron-donating ability of the 4-hydroxyl versus the 4-methoxyl group.The higher reactivity of the N-acetyl relative to the N-benzoyl derivatives is attributed to the ca. 30-fold increase in basicity of the N-acetyl functionality.The additive effect of the 4-hydroxyl and N-acetyl functionality on the basic quinol imine moiety makes compounds having both of the groups difficult to isolate in aqueous media.This serves as a limitation for the preparation of the quinol imine derivative of N-acetyl-2-aminofluorene via the anodic oxidation methods reported herein.
- Novak, Michael,Helmick, John S.,Oberlies, Nicholas,Rangappa, Kanchugarakoppal S.,Clark, William M.,Swenton, John S.
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p. 867 - 878
(2007/10/02)
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- Oxidations Of Substituted Phenols With Hypervalent Iodine : Applications To The Phthalide Annulation Route To Anthraquinones
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Substituted phenols are oxidized by phenyliodonium diacetate in methanol to yield either cyclohexa-2,4-dienones or the isomeric 2,5-dienones depending upon the structure of the phenol.Annulation of these oxidation products with the anion of 3-cyanophthali
- Mitchell, Anthony S.,Russell, Richard A.
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p. 545 - 548
(2007/10/02)
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- Spiro-annulated 2,5-cyclohexadienones via oxidation of 2'-alkenyl-p-phenyl phenols with iodobenzene diacetate
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The oxidation of 2-alkenyl-substituted p-phenyl phenols via iodobenzene diacetate gives spiro-annulated-2,5-cyclohexadienones.
- Callinan,Chen,Morrow,Swenton
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p. 4551 - 4552
(2007/10/02)
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- Structural and Solvent/Electrolyte Effects on the Selectivity and Efficiency of the Anodic Oxidation of Para-Substituted Aromatic Ethers. An Efficient Route to Quinol Ether Ketals and Quinol Ethers
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The anodic oxidations of the methyl ethers of p-arylphenols C6H4, o-C6H4, o-HO2CC6H4>, the 2-hydroxyethyl ethers of p-arylphenols , and the 2-hydroxyethyl ethers of p-alkylphenols and 4-methyl-1-naphthol were studied.The p-aryl aromatic ethers underwent anodic oxidation in good yield to give the corresponding p-quinol ether ketals.The ratio of nuclear to side-chain products from anodic oxidation of p-alkylanisole derivatives is dependent upon the electrolysis conditions.The 2-hydroxyethyl ether derivatives of p-alkylphenols markedly favor the formation of nuclear oxidation products - providing a useful route to the corresponding p-quinol ether ketals.In addition, methanolic potassium fluoride improves the efficiency of these anodic oxidation processes by about 400percent relative to methanolic potassium hydroxide.These reactions were performed at a constant current (1.0-2.0 A) in a single cell and serve as preparative routes to p-quinol ether ketals and quinol ethers via acid hydrolysis.
- Capparelli, Michael P.,DeSchepper, Richard E.,Swenton, John S.
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p. 4953 - 4961
(2007/10/02)
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- ANODIC OXIDATION STUDIES OF OXYGENATED BIPHENYLS. CONVENIENT SYNTHETIC ROUTES TO CERTAIN FUNCTIONALIZED BIPHENYLS
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The anodic oxidation of oxygenated biphenyls produces phenyl-substituted p-quinol ether ketals in good-to-excellent yield.These compounds are useful substrates for preparation of more highly functionalized biphenyls.
- DeSchepper, Richard E.,Swenton, John S.
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p. 4831 - 4834
(2007/10/02)
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- STUDIES ON THE MECHANISM OF THE OXIDATION OF AROMATIC PRIMARY AMINES WITH LEAD TETRAACETATE
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The oxidation of eight substituted anilines with lead tetraacetate gives azo derivatives and products deriving from nucleophilic nuclear attack.A ligand transfer mechanism and a reaction path via aminium radical is suggested for these oxidations.
- Benedini, Francesca,Galliani, Guido,Nali, Micaela,Rindone, Bruno,Tollari, Stefano
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p. 343 - 346
(2007/10/02)
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