- Practical bromination of arylhydroxylamines with SOBr2 towards ortho-bromo-anilides
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A facile approach for synthesizing ortho-bromoanilides from readily available aryhydroxylamines and thionyl bromide is demonstrated in this work. Mild reaction conditions and broad scope of substrates ranging from heterocyclic structures to pharmaceutics-potential motifs are used in the reactions of this paper. Efficient bromination of ortho C–H bonds of the aryhydroxylamines has been achieved. Ortho-bromoanilide products were obtained in good to excellent yields, and model scaled-up reactions of this synthetic approach are shown in this work.
- Du, Yuanbo,Feng, Lei,Gao, Hongyin,Guo, Lirong,Lu, Haifeng,Xi, Zhenguo
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supporting information
(2021/05/19)
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- Concerted [1,3]-Rearrangement in Cationic Cobalt-Catalyzed Reaction of O-(Alkoxycarbonyl)-N-arylhydroxylamines
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O-(Alkoxycarbonyl)-N-arylhydroxylamines were efficiently converted to 2-aminophenol derivatives by cationic cobalt catalysts at 30 °C. The results of 18O-labeling experiments suggested that rearrangement of the alkoxycarbonyl group from the aniline nitrogen to the ortho position proceeded in an unprecedented [1,3] manner.
- Nakamura, Itaru,Owada, Mao,Jo, Takeru,Terada, Masahiro
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supporting information
p. 2194 - 2196
(2017/04/27)
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- Copper-Catalyzed Aerobic Decarboxylation/Ketooxygenation of Electron-Deficient Alkenes
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A copper-catalyzed ketooxygenation of electron-deficient alkenes was developed. This approach combines O-H alkylation, aerobic decarboxylation, and oxygenation in one transformation. Mechanistic investigation of this reaction showed that the copper salt is responsible for both generating the amidoxyl radical and promoting aerobic decarboxylation.
- Lu, Qingquan,Peng, Pan,Luo, Yi,Zhao, Ying,Zhou, Minxian,Lei, Aiwen
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supporting information
p. 18580 - 18583
(2016/01/25)
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- N-heterocyclic-carbene-catalyzed one-pot synthesis of hydroxamic esters
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The honey pot: The NHC-catalyzed reaction between nitrosobenzenes, aromatic/aliphatic aldehydes, and enals proceeded through an aza-benzoin-type reaction and an internal redox esterification to afford hydroxamic esters in good yields. Copyright
- Song, Xiaoxiao,Ni, Qijian,Grossmann, Andre,Enders, Dieter
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supporting information
p. 2965 - 2969
(2014/01/06)
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- Solid-phase extraction of plutonium(IV) an americium(III) using N-benzoylphenylhydroxylamine and its derivatives
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The recovery and separation of plutonium(IV) and americium(III) by solid-phase extraction (SPE) on alkylated silica gel S16 modified with N-benzoylphenylhydroxylamine (BPHA) and with its derivatives was studied. BPHA was modified by introducing into the p-position of the phenyl ring of electronactive substituents that differ in their hydrophobicity: CH3, Ph, Cl, F, and NO2. The SPE of plutonium(IV) and americium(III) was studied in the range of acidities from pH 8 to 1 M HNO3. The recovery and separation of these elements was shown to depend on the nature of the substituent, aqueous acidity, and the preparation of S16 to SPE experiments.
- Petrukhin,Spivakov,Morgalyuk,Malofeeva,Kuzovkina,Novikov
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experimental part
p. 1839 - 1846
(2012/01/31)
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- Photoacid generators (PAGs) based on N-acyl-N-phenylhydroxylamines for carboxylic and sulfonic acids
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Simple and efficient photoacid generators (PAGs) for carboxylic and sulfonic acids based on N-acyl-N-phenylhydroxylamines have been demonstrated. Irradiation of o-carboxylates and thermally rearranged o-arenesulfonates of N-acyl-N-phenylhydroxylamines using UV light (≥254 nm) in aqueous methanolic solution resulted in efficient generation of carboxylic and sulfonic acids, respectively. The carboxylic acid generation ability of N-acyl-N- phenylhydroxylamines was found to be dependent on their N-acyl substituents. Further, polymer bearing o-arenesulfonates of N-acyl-N-phenylhydroxylamine was synthesized and demonstrated as PAG for sulfonic acids.
- Ikbal, Mohammed,Jana, Avijit,Singh, N.D. Pradeep,Banerjee, Rakesh,Dhara, Dibakar
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scheme or table
p. 3733 - 3742
(2011/06/21)
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- Benzaldehyde lyase-catalyzed direct amidation of aldehydes with nitroso compounds
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Benzaldehyde lyase from the Pseudomonas fluorescens catalyzes the reaction of aromatic aldehydes with nitroso compounds and furnishes N-arylhydroxamic acids in high yields. Aromatic aldehydes and benzoins are converted into enamine-carbanion-like intermediates prior to their reaction with nitroso compounds. The kinetic resolution of rac-2-hydroxy-1,2-diphenylethanones furnished (S)-benzoins and arylhydroxamic acids with high enantioselectivities and conversions.
- Ayhan, Peruze,Demir, Ayhan S.
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supporting information; experimental part
p. 624 - 629
(2011/04/24)
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- N-HETEROCYCLIC CARBENE (NHC) CATALYZED SYNTHESIS OF HYDROXAMIC ACIDS
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A process for preparing hydroxamic acids is provided. The process comprises reacting an aldehyde with a nitroso compound in the presence of a N-heterocyclic carbene (NHC) catalyst.
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Page/Page column 27-28
(2008/12/07)
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- Asymmetric synthesis of N-aryl aziridines
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The reactions of a variety of N-arylhydroxamates as nitrogen transfer reagents to acryloyl derivatives of (-)-8-phenylmenthol, (-)-quinine and (-)-Oppolzer's sultam acting as Michael acceptors was studied. Poor to modest diastereoselection was observed in the formation of aziridines. The absolute structure of one of the pure diastereomers secured from Oppolzer's auxiliary was established by X-ray crystallography and hence the absolute configuration of the derived methyl-N-phenylaziridine-2-carboxylate could be assigned. Whilst only poor facial selectivity was observed for chiral hydroxamic acid prepared from dehydroabietic acid, moderate to good enantioselection of aziridines could be achieved with the chiral quaternary salts based on cinchona alkaloids, especially with that of cinchonine. A model is presented to explain the origin of enantioselection and a mechanism is proposed for the aziridination reaction.
- Aires-de-Sousa, Joao,Prabhakar, Sundaresan,Lobo, Ana M.,Rosa, Ana M.,Gomes, Mario J.S.,Corvo, Marta C.,Williams, David J.,White, Andrew J.P.
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p. 3349 - 3365
(2007/10/03)
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- Substituent effects in the micellar hydrolysis of N-phenylbenzohydroxamic acid under acidic conditions
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The rates of hydrolysis of some para-substituted N-phenylbenzohydroxamic acids (X.C6H4.(C = O).N(OH)C6H5; X = H, CH3, OCH3, F, NO2) under acidic conditions with cationic, anionic and nonionic surfactants have been measured. Substituent effects upon first order rate constants in water and at the micellar surface fitted Hammett equation, based on σ, σ+, σ- parameters. Values of 'p' increase with increasing surfactant concentration. The substituent effects indicate specific micellar influences on the rates and a difference in mechanism between the bulk aqueous phase and the micellar phase. The lipophilicity and polar effects of the substituents have also been evaluated.
- Ghosh, Kallol K.,Roy, Supriya
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p. 324 - 328
(2007/10/03)
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- Protolytic properties of benzoylphenylhydroxylamine grafted on a silica surface
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Equilibrium of dissociation and homoconjugation of molecules of benzoylphenylhydroxylamine (BPHA) grafted on a silica surface was studied in the range of ionic forces of aqueous solutions 0.1-1.0 mol/1 at 20°C. Energy inhomogeneities of samples of complexing silica were examined. The experimental results were interpreted in terms of the concept of an islet-type filling of the surface by grafted molecules. Protolytic properties of grafted BPHA were compared with those of similar compounds in solutions.
- Kholin,Khristenko,Konyaev
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p. 445 - 448
(2007/10/03)
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- A Novel Conversion of N-Aryl-N-methoxyamides into N-Arylhydroxamic Acids Using AlCl3/Thiol System
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Treatment of N-aryl-N-methoxyamides with AlCl3 in EtSH (or Me2S) generates the corresponding N-aryl-N-hydroxyamides in high yields.
- Kawase, Masami,Kitamura, Takahiro,Shimada, Masahiro,Kikugawa, Yasuo
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p. 887 - 892
(2007/10/02)
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- N-Arylhydroxamic Acids: Reaction of Nitroso Aromatics with α-Oxo Acids
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A practical and high-yielding route to N-arylhydroxamic acids from nitroso aromatics and α-oxo acids 1a-d is desctibed.In aqueous and acetic acid containing media, the reactions exhibit second-order reaction kinetics overall.In the aqueous medium, the rate constant (kobsd) for N-phenylacetohydroxamic acid (8b) formation increased with increasing +>, though there were some side pathways involving azoxybenzene formation.In general, kobsd for the reaction in the acetic acid containing medium was about one-tenth of that in HCl at pH 0.6.On a preparative scale, acetic acid is better than HCl, in that both reactants showed sufficient solubilities in acetic acid for a high reaction velocity and no side reaction was detected.With this method, the proximate carcinogens, N-(4-biphenylyl)acetohydroxamic acid (12b) and N-(2-fluorenyl)acetohydroxamic acid (13b), could be easily prepared.Under both conditions, the order of kobsd for the reactions of nitrosobenzene (2) with α-oxo acids 1a-d was glyoxylic (1a) > pyruvic (1b) 2-oxobutyric (1c) > benzoylformic (1d) acid.For the reactions of substituted nitrosobenzenes 3-6 with pyruvic acid (1b), the order of kobsd was p-phenyl (6) > unsubstituted (2) > p-chloro (5) > m-chloro (4) >> o-chloro (3) nitrosobenzene.The negative Hammett reaction constant value obtained indicates that an electron-donating substituent is preferable for the reaction.The reaction mechanism and other factors affecting N-arylhydroxamic acid formation are also descussed.
- Sakamoto, Yasuko,Yoshioka, Tadao,Uematsu, Takayoshi
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p. 4449 - 4453
(2007/10/02)
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- Novel Catalytic System consisting of a 3,3'-Tetramethylene-bridged 4-Methylthiazolium Salt Leading to the Partial Reduction of Nitrobenzene with Benzaldehyde to a Nitrone
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A 3,3'-tetramethylene-bridged 4-methylthiazolium salt catalyses the reduction of nitrobenzene with benzaldehyde and triethylamine in methanol-water to give a nitrone.
- Inoue, Hiroo,Tamura, Shigeo
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p. 141 - 142
(2007/10/02)
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- C-SUBSTITUTION REACTIONS OF C,N-DIARYL NITRONES.
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C,N-Diaryl nitrones react rapidly with N-bromosuccinimide in an aprotic solvent to yield among other products, the E and Z isomers of the C-succinimidyl substituted nitrones and a small amount of the corresponding hydroxamic acid.The sterochemistry of the C-succinimidyl niyrones was confirmed by an X-ray structure determination of the C,N-(dimethoxyphenyl) derivative 8e.In the presence of the base DABCO the formation of hydroxamic acids is suppressed and the Z C-succinimidyl nitrone forms more rapidly than the more stable E isomer.Several mechanistic rationalisations of this observed stereochemistry are discussed.
- Lobo, Ana M.,Prabhakar, Sundaresan,Rzepa, Henry S.,Skapski, Andrzej C.,Tavares, M. Regina,Widdowson, David A.
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p. 3833 - 3842
(2007/10/02)
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- Novel Reactions: Part I - Facile Synthesis of Substituted ortho-Chloranilines from Nitrobenzene Derivatives
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N-Substituted benzo and acetohydroxamic acids (5), prepared from N-arylhydroxylamines and benzoyl or acetyl chloride, react readily with thionyl chloride at low temperature to give ortho-chloroanilide derivatives (6) in good yield.The latter (6) on hydrolysis give ortho-chloroanilines (10).Since the N-arylhydroxylamines are obtained from nitroarenes by partial reduction, the overall reaction amounts to the preparation of 10 from nitroarenes.
- Ayyangar, N. R.,Kalkote, U. R.,Nikrad, P. V.
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p. 872 - 877
(2007/10/02)
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- Meldrum's Acid in Organic Synthesis. VI. Synthesis of 2-Substituted Indoles from Acyl Meldrum's Acids and Phenylhydroxylamine via Sigmatropic Rearrangement
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Phenylhydroxylamine (13) oxalate was quite easily acylacetylated by heating with an equimolar amount of acyl Meldrum's acid (4) in acetonitrile to give an N-acylacetylphenylhydroxylamine (14) in high yield.When 14 was treated with another equimolar amount of the same 4 in refluxing toluene, a series of reactions, O-acylacetylation, 1-aza-1'-oxasigmatropic rearrangement, decarboxylation, dehydrative cyclization, and deacylation, occured consecutively to give a 2-substituted indole (16) in fair yield, though sometimes accompanied by the formation of a 5-substituted 4-isoxazolin-3-one (17).N-Benzoyl, N-acetyl, and N-benzyloxycarbonyl derivatives of phenylhydroxylamine (18) were treated with phenylacetyl Meldrum's acid (4i) in refluxing benzene containing copper powder to give readily rearranged ortho alkylation products (19), which were converted to the corresponding N-acyl-2-benzylindoles (20) by treatment with hydrochloric acid in boiling ethanol or with anhydrous p-toluenesulfonic acid in benzene at room temperature.Keywords - acyl Meldrum's acid; phenylhydroxylamine; N-acylacetylphenylhydroxylamine; 2-substituted indole; 1-aza-1'-oxasigmatropic rearrangement; acid-catalyzed cyclization
- Mohri, Kunihiko,Oikawa, Yuji,Hirao, Ken-ichi,Yonemitsu, Osamu
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p. 3097 - 3105
(2007/10/02)
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- Electron-transfer Reductions by Active Aldehydes catalysed by Thiazolium Salt in the Presence of Triethylamine
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3-Benzylthiazolium salts, in methanol containing triethylamine, catalyse the redox reaction in which aldehydes are oxidized to methyl esters concurrently with the reduction of several organic compounds.
- Inoue, Hiroo,Higashiura, Kunihiko
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p. 549 - 550
(2007/10/02)
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