- MECHANISM OF ISOMERISATION OF ortho OR para BROMO PHENOLS IN SUPERACIDS
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In superacids ortho or para bromo phenols are isomerised into the meta bromo isomers.In SbF5-HF, the process is intramolecular and proceeds by a 1,2-Br shift.In CF3SO3H, the mechanism involves loss of bromine, followed by meta bromination.
- Jacquesy, Jean-Claude,Jouannetaud,Marie-Paule
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Read Online
- 1,5-diketones from 3,4-dihydropyranones: An application in the synthesis of (±)-α-herbertenol
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An approach to 1,5-diketones involving the addition of organolithium reagents to 3,4-dihydropyranones is described. Good yields are obtained when reactions are quenched with trimethylsilyl chloride prior to hydrolytic work up and the organolithium reagent contains a Lewis basic group adjacent to the carbon to lithium bond. The method has been applied in a short synthesis of the fungicidal sesquiterpene (±)-α-herbertenol.
- Harrowven, David C.,Hannam, Joanne C.
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Read Online
- Visible light-induced mono-bromination of arenes with BrCCl3
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A highly efficient and regioselective bromination of electron-rich arenes and heteroarenes using commercially available BrCCl3as a “Br” source has been developed. The reaction was performed in air under mild conditions with photocatalyst Ru(bpy)3Cl2·6H2O, avoiding the usage of strong acids and strong oxidants. Mono-brominated products were obtained with medium to excellent yields (up to 94%). This strategy has shown good compatibility and highpara-selectivity, which will facilitate the complicated synthesis.
- Fan, Jiali,Wei, Qiancheng,Zhu, Ershu,Gao, Jing,Cheng, Xiamin,Lu, Yongna,Loh, Teck-Peng
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supporting information
p. 5977 - 5980
(2021/06/18)
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- Eco-Friendly Methodology for the Formation of Aromatic Carbon–Heteroatom Bonds by Using Green Ionic Liquids
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A new sustainable method is reported for the formation of aromatic carbon–heteroatom bonds under solvent-free and mild conditions (no co-oxidant, no strong acid and no toxic reagents) by using a new type of green ionic liquid. The bromination of methoxy arenes was chosen as a model reaction. The reaction methodology is based on only using natural sodium bromine, which is transformed into an electrophilic brominating reagent within an ionic liquid, easily prepared from the melted salt FeCl3 hexahydrate. Bromination reactions with this in-situ-generated reagent gave good yields and excellent regioselectivity under simple and environmentally friendly conditions. To understand the unusual bromine polarity reversal of sodium bromine without any strong oxidant, the molecular structure of the reaction medium was characterised by Raman and direct infusion electrospray ionisation mass spectroscopy (ESI-MS). An extensive computational investigation using density functional theory methods was performed to describe a mechanism that suggests indirect oxidation of Br? through new iron adducts. The versatility of the methodology was successively applied to nitration and thiocyanation of methoxy arenes using KNO3 and KSCN in melted hexahydrated FeCl3.
- Richards, Kenza,Petit, Eddy,Legrand, Yves-Marie,Grison, Claude
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supporting information
p. 809 - 814
(2020/11/30)
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- Bridged nitrogen-containing heterocyclic metallocene compound as well as preparation method and application thereof
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The invention provides a bridged nitrogen-containing heterocyclic metallocene compound, which has the structure shown in the formula (I). In-flight R1 A substituted or unsubstituted C1 - C30 alkyl group, a substituted or unsubstituted C3 - C30 cycloalkyl group, a substituted or unsubstituted C6 - C30 aromatic group, a substituted or unsubstituted C6 - C30 aromatic heterocyclic group. R2 AND R3 A C1 - C10 alkyl group or a phenyl group is each independently selected. R4 A substituted or unsubstituted C1 - C10 alkyl, substituted or unsubstituted C6 - C20 aromatic group. X Is a halogen, a substituted or unsubstituted alkyl group. M Is 4th-valent transition metal titanium. Zircon or hafnium. Compared with the prior art, the metallocene compound provided by the invention is convenient to modify, high in catalytic activity and good in temperature resistance, can maintain high catalytic activity under high-temperature conditions, can catalyze copolymerization of ethylene and α - olefin, and can obtain a polymer product with high molecular weight and high comonomer insertion rate.
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Paragraph 0100; 0121
(2021/10/16)
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- New procedure for the highly regioselective aerobic bromination of aromatic compounds using copper-based nanocatalyst
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A new procedure for the highly regioselective aerobic bromination of aromatic compounds in the presence of copper-based nanoparticles (CuO/ZnO nanocatalyst) under reflux condition is described. Mechanistic parameters are discussed and the plausible mechanism is proposed. Recyclability of the CuO/ZnO nanocatalyst has also been explored upon aerobic bromination of aromatic compounds.
- Albadi, Jalal,Jalali, Mehdi
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p. 234 - 239
(2020/02/29)
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- Atom-economical brominations with tribromide complexes in the presence of oxidants
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Bromination is an important transformation in organic synthesis, and novel efficient bromination techniques are still required. Herein, we demonstrate atom-economical brominations using (DMI)2HBr3, a novel tribromide complex, with oxidants such as DMSO and Oxone. Using this system, olefinic and aromatic brominations, as well as selective α-monobrominations of ketones proceeded well to afford the desired bromides in good yields. Importantly, in these reactions all of the bromine atoms in this complex are used to brominate.
- Yubata, Kotaro,Matsubara, Hiroshi
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supporting information
p. 1001 - 1004
(2019/03/13)
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- Environmentally benign indole-catalyzed position-selective halogenation of thioarenes and other aromatics
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Halogenated aromatic compounds are the cores of many pharmaceutical, agricultural and chemical products but they are commonly prepared using electrophilic halogenation reactions in non-green chlorinated solvents under harsh conditions. A separate problem happens in the aromatic halogenation of thioarenes because they readily undergo oxidative side-reactions. Herein we report an environmentally benign electrophilic bromination of aromatics using an indole-catalytic protocol, which is suitable for a wide range of substrates including thioarenes.
- Shi, Yao,Ke, Zhihai,Yeung, Ying-Yeung
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supporting information
p. 4448 - 4452
(2018/10/17)
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- Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
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The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C?H functionalization and arene sp2 C?H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 C?Br and sp2 C?Br functionality. (Figure presented.).
- Ni, Shengjun,El Remaily, Mahmoud Abd El Aleem Ali Ali,Franzén, Johan
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supporting information
p. 4197 - 4204
(2018/09/25)
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- Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
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Benzylic sp 3 C-H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO 2 Et, CO 2 H, CN or NO 2, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.
- Zhao, Mengdi,Li, Meiqi,Lu, Wenjun
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supporting information
p. 4933 - 4939
(2018/12/14)
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- Ormetoprim synthesis method
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The invention provides an ormetoprim synthesis method. The method includes steps: subjecting p-cresol and dimethyl carbonate to phenolic hydroxymethylation to obtain a compound I; subjecting the compound I and potassium bromide to bromination reaction under an acetic anhydride-nitric acid system to obtain a compound II; taking cuprous chloride as a catalyst, and subjecting the compound II and sodium methylate methanol solution to methoxylation reaction to obtain a compound III; subjecting the compound III and a VHA reagent to formylation reaction to obtain a compound IV; subjecting the compound IV to reaction with sodium methylate and acrylonitrile methanol solution to obtain a compound V; after the compound V is subjected to alkali isomerization to obtain a vinyl ether structure, subjecting to addition reaction with methyl alcohol and direct condensation and cyclization with guanidine to finally obtain a compound VI which is a final product namely ormetoprim. Defects in the prior art are overcome, and the provided ormetoprim synthesis method has advantages of technical simplicity, easiness in acquisition of starting materials, high yield and low production cost.
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Paragraph 0033; 0034; 0046; 0047
(2017/11/16)
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- Bromination of Anisoles Using N-Bromophthalimide: A Synthetic and Kinetic Approach
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N-Bromophthalimide (NBP)-triggered bromination of aromatic compounds has been studied in the presence of aqueous acetic acid. Reaction Kinetics indicated first order in [NBP] and zero order in [Anisole]. The reactions afforded very good yields of corresponding bromo derivatives under kinetic conditions. The mechanism of the reaction is explained through the formation of acetyl hypobromite due to the interaction of NBP and acetic acid, which in turn reacts with anisole to afford a bromo derivative of anisole.
- Anjaiah,Kumar, M. Satish,Srinivas,Rajanna
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- A Metal-Free and Ionic Liquid-Catalyzed Aerobic Oxidative Bromination in Water
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A metal-free aerobic oxidative bromination of aromatic compounds in water has been developed. Hydrobromic acid is used as a bromine source and 2-methylpyridinium nitrate ionic liquid is used as a recyclable catalyst. Water is used as the reaction mediate. This is the first report of aerobic oxidative bromination using only catalytic amount of metal-free catalyst. This system shows not only high bromine atom economy, but also high bromination selectivity. The possible mechanism and the role of the catalyst in this system have also been discussed.
- Wang, Jian,Chen, Shu-Bin,Wang, Shu-Guang,Li, Jing-Hua
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p. 513 - 517
(2015/03/30)
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- Aerobic oxidative bromination of arenes using an ionic liquid as both the catalyst and the solvent
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A method for the bromination of alkoxy-substituted benzenes and naphthalenes was developed by using the residual oxygen in the reaction tube as the oxidant, and [Bmim]NO3 (1-butyl-3-methylimidazolium nitrate) ionic liquid as both the catalyst and the solvent. No other reagent apart from the ionic liquid and molecular bromine was used in the reactions, and basically all the bromine atoms in the bromine source were transferred to the bromination products, showing that the presented protocol is highly atom economic and practical.
- Ren, Yun-Lai,Wang, Binyu,Tian, Xin-Zhe,Zhao, Shuang,Wang, Jianji
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supporting information
p. 6452 - 6455
(2015/11/16)
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- Selective oxidation of alcohols with alkali metal bromides as bromide catalysts: Experimental study of the reaction mechanism
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A bromide-catalyzed oxidation of alcohols was developed which proceeded in the presence of an alkali metal bromide and an oxidant under mild conditions. The reaction involved an organic-molecule-free oxidation using KBr and Oxone and a Br?nsted acid assisted oxidation using KBr and aqueous H 2O2 solution to provide a broad range of carbonyl compounds in high yields. Moreover, the bromide-catalyzed oxidation of primary alcohols enabled the divergent synthesis of carboxylic acids and aldehydes under both reaction conditions in the presence of TEMPO. A possible catalytic mechanism was suggested on the basis of various mechanistic studies.
- Moriyama, Katsuhiko,Takemura, Misato,Togo, Hideo
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p. 6094 - 6104
(2014/07/21)
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- Nuclear versus side-chain bromination of 4-methoxy toluene by an electrochemical method
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GRAPHICAL ABSTRACT The electrochemical bromination of 4-methoxy toluene by two-phase electrolysis yields 3-bromo 4-methoxy toluene at first, which subsequently undergoes side-chain bromination to give 3-bromo 4-methoxy benzyl bromide as a final product in 86% yield. The two-phase electrolysis consists of 25-50% NaBr as aqueous electrolyte and CHCl3 containing aromatic compound as organic phase. The reaction temperature is maintained at 10-25 °C. The probable orientation of bromine atom in an alkyl aromatic compound (nuclear versus side chain) is explained from the experimental result.
- Kulangiappar,Anbukulandainathan,Raju
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p. 2494 - 2502
(2014/08/05)
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- The oxidative halogenations of arenes in water using hydrogen peroxide and halide salts over an ionic catalyst containing sulfo group and hexafluorotitanate
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An ionic compound, bis[1-methyl-3-(3′-sulfopropyl)imidazolium] hexafluorotitanate (1), was proved to be the efficient and recyclable catalyst for the oxidative halogenations of arenes in water using H2O 2 as the oxidant and halide salts as the halogenation sources. The mono-halogenated products were obtained selectively by this method. The synergetic catalytic effect coming from the two incorporated functionalities of SO3H and [TiF6]2- was manifested in 1. The halogenation rate catalyzed by 1 was in the ranking of NaBr NaCl > KI. The UV-vis and FT-IR analyses indicated that the successful formation and regeneration of the active peroxo-Ti species (1A) with the aid of proton acid guaranteed the recycling uses of 1.
- Wang, Ling,Wang, Sa-Sa,Vo-Thanh, Giang,Liu, Ye
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- Poly(4-vinylpyridinium bromochromate): An efficient reagent for bromination of aromatic compounds
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A simple and efficient method for the bromination of various aromatic compounds by using poly(4-vinylpyridinium bromochromate) is reported. This method has several advantages such as good selectivity between ortho and para positions of aromatic compounds, simple workup, short reaction times, and high yields of the products.
- Albadi, Jalal,Tajik, Hassan,Keshavarz, Mosadegh,Abedini, Masoumeh
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p. 179 - 181
(2013/07/27)
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- Polymer-anchored Cu(II) complex as an efficient catalyst for selective and mild oxidation of sulfides and oxidative bromination reaction
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A new polymer-anchored Cu(II) complex has been tested for the oxidation of sulfides and in oxidative bromination reaction with hydrogen peroxide as oxidant. Sulfides have been selectively oxidized to corresponding sulfoxides in excellent yields and in presence of KBr as bromine source, organic substrates have been selectively converted to mono bromo substituted compounds. The polymer-anchored Cu(II) catalyst could be easily recovered by simple filtration and reused more than six times without appreciable loss of its initial activity. Graphical Abstract: [Figure not available: see fulltext.]
- Islam, Sk. M.,Roy, Anupam Singha,Mondal, Paramita,Salam, Noor,Paul, Sumantra
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p. 225 - 233
(2013/03/13)
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- Selective oxidation of sulfides and oxidative bromination of organic substrates catalyzed by polymer anchored Cu(II) complex
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A new polymer-anchored Cu(II) complex has been synthesized and characterized. The catalytic performance of the complex has been tested for the oxidation of sulfides and in oxidative bromination reaction with hydrogen peroxide as the oxidant. Sulfides have been selectively oxidized to the corresponding sulfoxides in excellent yields and in the presence of KBr as the bromine source, organic substrates have been selectively converted to mono bromo substituted compounds using polymer-anchored Cu(II) catalyst. This catalyst showed excellent catalytic activity, high selectivity, and recyclability. The polymer-anchored Cu(II) catalyst could be easily recovered by filtration and reused more than five times without appreciable loss of its initial activity.
- Islam,Roy, Anupam Singha,Mondal, Paramita,Tuhina, Kazi,Mobarak, Manir,Mondal, John
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supporting information; experimental part
p. 127 - 131
(2012/01/17)
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- Catalyst and solvent-free bromination of toluene derivatives by HBr-H 2O2 with visible-light photocatalysis using a continuous-flow micro reactor
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The efficiency of the bromination of toluene derivatives has been improved significantly by utilising a combination of hydrogen peroxide (30%) and hydrogen bromide (40%) in a continuous-flow micro reactor. This catalyst and solvent-free reaction takes place by visible-light photocatalysis.
- Yu, Wu-Bin,Yu, Dong-Ping,Zheng, Ming-Ming,Shan, Shu-Ting,Li, Yu-Jin,Gao, Jian-Rong
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experimental part
p. 258 - 260
(2012/09/22)
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- In situ acidic carbon dioxide/water system for selective oxybromination of electron-rich aromatics catalyzed by copper bromide
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Carbon dioxide, being one of the major greenhouse gases responsible for global warming, its atmospheric level grows ever faster since the beginning of industrial era. Great efforts have been devoted to developing versatile technologies/processes to adjust and manipulate the rapid growth of CO 2 emission. Besides CO2 capture and storage/sequestration (CCS) to control its emission, chemical utilization of the captured CO 2 (CCU) emerges to be a rational technique for economical benefits as well as environmental concerns. As for the aim of CO2 utilization, an environmentally benign CO2/water reversible acidic system was developed for the copper (II)-catalyzed selective oxybromination of electron-rich aromatics without the need of any conventional acid additive and organic solvent. Notably, up to 95% yields of the bromination products were attained with good regio-selectivity when cupric bromide was used as the catalyst and lithium bromide as a cheap and easy handling bromine source under supercritical CO2. The catalytic system worked well for electron-rich aromatics including ethers, sulfides and mesitylene. Carbonic acid in situ formed from CO2 and water is supposed to act as the proton donator in the Bronsted acid-promoted reaction. Notably, CO2 in this study serves as a reaction medium and a promoter in conjunction with water and also provides safe environment for aerobic reactions. Given with excellent reaction efficiency as well as no need of neutralization disposal, this process thus represents an environmentally friendly approach for aerobic bromination of aromatics with essential reduction of CO2 emission as well as an economically beneficial way for application of captured CO2.
- Liu, An-Hua,Ma, Ran,Zhang, Meng,He, Liang-Nian
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- PHOSPHORESCENT MATERIAL, THEIR PREPARATIONS AND APPLICATIONS
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The subject invention is directed to tetradentate bis-(NHC carbenes) alkylene ligand Pt(II) complexes, tetradentate bis-(NHC carbenes) alkylene ligands, and its ligand precursors, for preparation of the Pt(II) complexes. The Pt(II) complexes show a deep blue emission with an improved quantum efficiency and can be used for fabrication of OLEDs with an electroluminescence layer that comprise the bis-(NHC carbenes) alkylene ligand Pt(II) complexes.
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Page/Page column 3
(2012/12/14)
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- An efficient and regioselective monobromination of electron-rich aromatic compounds using catalytic hypervalent iodine(III) reagent
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An efficient and regioselective monobromination of electron-rich aromatic compounds is reported in which iodobenzene is used as the recyclable catalyst in combination with m-chloroperbenzoic acid as the terminal oxidant. The bromination of electron-rich aromatic compounds with lithium bromide was fast in tetrahydrofuran at room temperature, providing regioselective monobrominated products in good yields.
- Zhou, Zhongshi,He, Xuehan
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experimental part
p. 207 - 209
(2011/03/18)
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- In situ acidic carbon dioxide/ethanol system for selective oxybromination of aromatic ethers catalyzed by copper chloride
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An environmentally benign carbon dioxide/ethanol reversible acidic system was developed for the copper(II)-catalyzed regioselective oxybromination of aromatic ethers without the need of any conventional acid additive and organic solvent. Good to excellent yields together with very good regioselectivity were achieved when easily available cupric chloride dihydrate was used as catalyst and lithium bromide as the cheap and easy-to-handle bromine source under supercritical carbon dioxide conditions. Notably, the catalytic system worked well for a wide range of aromatic ethers including sulfides, resulting in the formation of the mono-brominated products in high yields and exclusive regioselectivity. The alkylcarbonic acid in situ formed from ethanol and carbon dioxide is assumed to play the crucial role in the Braonsted acid-promoted reaction, which could probably act as the proton donator, and was studied employing in situ FT-IR technique under carbon dioxide pressure by monitoring the vibration shift of the hydroxy group of ethanol. Given with excellent bromine atom efficiency as well as no need of neutralization in waste disposal, this approach thus represents a greener pathway for the aerobic bromination of aromatic ethers. A possible catalytic cycle for the in situ alkylcarbonic acid-assisted oxybomination and the effect of supercritical carbon dioxide, i.e., activation of alcohol and enhancement of mass transfer are also discussed. Copyright
- Liu, An-Hua,He, Liang-Nian,Hua, Fang,Yang, Zhen-Zhen,Huang, Cheng-Bin,Yu, Bing,Li, Bin
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experimental part
p. 3187 - 3195
(2012/01/06)
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- Merging organocatalysis with an indium(III)-mediated process: A stereoselective α-alkylation of aldehydes with allylic alcohols
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Curiosity killed the CAT..ions! The use of stabilized cationic intermediates can be considered as a new frontier in the development of stereoselective reactions. An organocatalytic procedure mediated by the MacMillan imidazolidinone catalyst was coupled with an InBr3-mediated process for the development of a novel stereoselective allylation reaction of aldehydes. Up to 98 % ee and up to 5:1 d.r. were obtained in the process.
- Capdevila, Montse Guiteras,Benfatti, Fides,Zoli, Luca,Stenta, Marco,Cozzi, Pier Giorgio
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supporting information; experimental part
p. 11237 - 11241
(2010/11/04)
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- Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
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A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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experimental part
p. 4429 - 4439
(2009/10/09)
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- Synthesis of arylbromides from arenes and Nbromosuccinimide bromosuccinimide (NBS) in acetonitrile - A convenient method for aromatic bromination
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Regioselective and chemoselective electrophilic bromination of a wide series of activated arenes using N-bromosuccinimide (NBS) in acetonitrile occurs readily. Environmentally friendly conditions, large substrate scope, and ease of synthesis enhance the utility of this method over other electrophilic bromination conditions.
- Zysman-Colman, Eli,Arias, Karla,Siegel, Jay S.
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experimental part
p. 440 - 447
(2009/12/01)
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- A novel simple and efficient bromination protocol for activated arenes
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An efficient, high yielding, and environmentally benign bromination using an alkali metal bromide as the bromine source is disclosed. Investigation of the protocol revealed that the method operates for activated arenes producing the corresponding monobrominated products in good to excellent yields.
- Tsoukala, Anna,Liguori, Lucia,Occhipinti, Giovanni,Bj?rsvik, Hans-Rene?
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supporting information; experimental part
p. 831 - 833
(2009/05/07)
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- Association of fluorous "phase-vanishing" method with visible-light activation in benzylic bromination by bromine
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In this study the "phase-vanishing" method for diffusion-controlled addition of a reagent (Br2) to a reaction phase via a fluorous membrane (C8F18) is combined with an additional mode of activation (visible-light) to achieve the benzyl bromination of various alkyl-substituted aromatic compounds in a concentrated solution. Benzyl bromination of p-tert-butyl-toluene proceeded in various solvents including hexane and methanol, while the reaction of the neat substrate showed a similar selectivity as in carbon tetrachloride. The effect of the substituent on the para position of toluene on the course of bromination revealed three processes: benzyl bromination with H, Me, tBu and CO2Et substituents, aromatic bromination with OMe and NHAc substituents and the reaction of the 4-acetyl derivative at the substituent to form an α-bromo ketone. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Podgorsek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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p. 483 - 488
(2007/10/03)
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- Visible light induced 'on water' benzylic bromination with N-bromosuccinimide
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Benzylic bromination of various 4-substituted toluenes (Me, tert-Bu, COOEt and COMe) was effectively conducted with NBS in pure water and with a 40 W incandescent light-bulb as an initiator of the radical chain process, while electron donating groups (OMe and NHAc) directed the reaction to electrophilic aromatic substitution.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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p. 1097 - 1099
(2007/10/03)
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- A simple and regioselective α-bromination of alkyl aromatic compounds by two-phase electrolysis
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Electrochemical bromination of toluene and substituted toluenes by two-phase electrolysis yields the corresponding α-brominated products. The reaction has been carried out in a single compartment cell with platinum electrodes at 0°C in chloroform using an aqueous sodium bromide solution (60%) containing a catalytic amount of HBr. Two-phase electrolysis results in high yields (60-95%) of monobromo compounds with very high regioselectivity (>95%).
- Raju,Kulangiappar,Anbu Kulandainathan,Muthukumaran
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p. 7047 - 7050
(2007/10/03)
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- OOxidative bromination of activated aromatic compounds using aqueous nitric acid as an oxidant
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Oxidative bromination of activated aromatic compounds using alkali metal bromide salts and aqueous nitric acid to the corresponding bromo-derivatives is achieved in a liquid-liquid, two-phase system under ambient conditions. Nitric acid offers a dual function of an oxidant as well as a proton donor, which is essential for oxidative bromination using metal bromide salts. Bromination as well as chlorination could be accomplished with this simple system.
- Joshi, Ashutosh V.,Baidossi, Mubeen,Mukhopadhyay, Sudip,Sasson, Yoel
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p. 568 - 570
(2013/09/02)
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- Novel bromination method for anilines and anisoles using NH 4Br/H2O2 in CH3COOH
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A simple, efficient, regioselective, environmentally safe, and economical method for the oxybromination of anilines and anisoles without catalyst is reported. The electrophilic substitution of bromine generated in situ from ammonium bromide as a bromine source and hydrogen peroxide as an oxidant for the first time.
- Krishna Mohan,Narender,Srinivasu,Kulkarni,Raghavan
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p. 2143 - 2152
(2007/10/03)
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- Mild and regioselective oxidative bromination of aromatic compounds using ammonium bromide and oxone
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The selective mono-bromination of various activated aromatic compounds is reported using in situ generated bromine from NH4Br as a bromine source and oxone as an oxidant for the first time.
- Narender,Mohan, K.V.V. Krishna,Kulkarni,Raghavan
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p. 597 - 598
(2007/10/03)
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- Halogenation of Aromatic Compounds by N-chloro-, N-bromo-, and N-iodosuccinimide
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An efficient and mild method for the halogenation of aromatic compounds using N-chloro-, N-bromo-, and N-iodosuccinimide in the presence of NH 4NO3 or FeCl3 in acetonitrile was developed.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
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p. 932 - 933
(2007/10/03)
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- Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds using iodine and bromine
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Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds with iodine and bromine or their sodium salts proceed well in the presence of Fe(NO3) 3·1.5N2O4/charcoal in CH 2Cl2 at room temperature.
- Firouzabadi,Iranpoor,Shiri
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p. 8781 - 8785
(2007/10/03)
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- Environmentally-friendly Wohl-Ziegler bromination: Ionic-liquid reaction and solvent-free reaction
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Environmentally-friendly Wohl-Ziegler bromination of benzylic methyl groups was successfully camed out in ionic-liquid and solvent-free systems, to produce the corresponding benzylic bromides in good to moderate yields.
- Togo, Hideo,Hirai, Takeshi
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p. 702 - 704
(2007/10/03)
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- An anion-induced regio- and chemoselective acylation and its application to the synthesis of an anticancer agent
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Figure presented An efficient Grignard- and organolithium-induced regio- and chemoselective anionic acylation is reported. A number of tricyclic ketones are prepared in good to excellent yields via this method. This method is complementary to the Frieldel-Crafts acylation for electron-deficient substrates. A novel anisole-based Grignard reagent was developed to effect the cyclization of sterically hindered substrates. This novel reagent has been successfully applied to the synthesis of Sch 66336, a candidate for oncologic treatment.
- Poirier, Marc,Chen, Frank,Bernard, Charles,Wong, Yee-Shing,Wu, George G.
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p. 3795 - 3798
(2007/10/03)
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- A simple and practical halogenation of activated arenes using potassium halide and oxone in water-acetonitrile medium
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A simple and practical halogenation of activated arenes using a reagent combination of potassium halide and oxone in water-acetonitrile medium is presented. The halogenated products were obtained with good yields and in high purity.
- Tamhankar,Desai,Mane,Wadgaonkar,Bedekar
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p. 2021 - 2027
(2007/10/03)
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- Hydrochloric acid catalysis of N-bromosuccinimide (NBS) mediated nuclear aromatic brominations in acetone
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Nuclear bromination of activated aromatic substrates can be achieved quickly and in high yields using N-bromosuccinimide (NBS) in acetone with 1 M HCl catalysis.
- Andersh, Brad,Murphy, Drew L.,Olson, Ryan J.
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p. 2091 - 2098
(2007/10/03)
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- Environment friendly regiospecific bromination of aromatic ethers by N- bromosuccinimide in presence of montmorillonite
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Reaction of methoxybenzenes and naphthalenes with N-bromosuccinimide in presence of montmorillonite clay (K10) affords excellent yields of regiospecifically brominated products under mild conditions in the absence of solvent.
- Perumal,Vijayabaskar,Gomathi,Selvaraj
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p. 603 - 604
(2007/10/03)
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- Simple and practical halogenation of arenes, alkenes and alkynes with hydrohalic acid/H2O2 or TBHP)
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A simple protocol for the halogenation of arenes utilizing a combination of aqueous hydrogen peroxide (34 %) or tert-butylhydroperoxide (70 %) and hydrohalic acid is presented. A similar procure of oxyhalogenation involving the in situ generation of positive halogen reagents is applied for the preparation of vicinal trans-dibromoalkanes and dichloroalkanes from alkenes. The reaction of alkenes with a combination of hydrochloric acid and hydrobromic acid with hydrogen peroxide gave a mixture of 1-bromo 2-chloro alkanes and 1,2-dibromoalkanes: Oxidative bromination of alkynes is also reported under similar conditions.
- Barhate, Nivrutti B.,Gajare, Anil S.,Wakharkar, Radhika D.,Bedekar, Ashutosh V.
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p. 11127 - 11142
(2007/10/03)
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- Enantioselective synthesis of dityrosine and isodityrosine via asymmetric phase-transfer catalysis
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Application of N-anthracenylmethyl cinchonidinium chloride quaternary ammonium phase-transfer catalysts to the enantio- and diastereoselective synthesis of dityrosine and isodityrosine is reported. Under liquid-liquid phase-transfer conditions the key α-amino acid substituents are introduced with high enantioselectivity (≥95%e.e.).
- Lygo
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p. 1389 - 1392
(2007/10/03)
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- Electrophilic Aromatic Bromination Using Bromodimethylsulfoniuin Bromide Generated in Situ
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It has been shown that bromodimethylsulfonium bromide, generated in situ by treating dimethyl sulfoxide with aqueous hydrobromic acid, is a milder and more selective reagent for electrophilic aromatic bromination than elemental bromine.
- Majetich, George,Hicks, Rodgers,Reister, Steven
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p. 4321 - 4326
(2007/10/03)
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- A new mild and selective reagent for nuclear bromination
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Hexamethylene tetramine tribromide HMTAHBr3 - a new, mild and regioselective brominant is reported for bromination of aromatic hydrocarbons, substituted ethers, phenols and anilides in high yields.
- Bisarya,Rao
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p. 779 - 788
(2007/10/02)
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- Syntheses of Antibacterial 2,4-Diamino-5-benzylpyrimidines. Ormetoprim and Trimethoprim
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A general and mild method for the synthesis of 2,4-diamino-5-benzylpyrimidines was achieved by the Friedel-Crafts reaction between 2-(methoxymethylene)-3-methoxypropanenitrile (10) and an activated aromatic substrate followed by treatment with guanidine.The method is illustrated by a synthesis of ormetoprim (2) in 75percent overall yield from 3,4-dimethoxytoluene (12).Efficient syntheses of trimethoprim (1) and 2 were also accomplished via prior base-catalyzed 1,3-prototropic isomerization of cinnamonitriles 19 and 20, respectively, followed by condensation with guanidine. 12 was prepared from 3-bromo-4-methoxytoluene by a Cu(I)-catalyzed displacement of bromine by methoxide and 4,5-dimethoxy-2-methylbenzaldehyde was obtained from 12 in 87percent yield by a pyridine-catalyzed Vilsmeier reaction using DMF-POCl3.
- Manchand, Percy S.,Rosen, Perry,Belica, Peter S.,Oliva, Gloria V.,Perrotta, Agostino V.,Wong, Harry S.
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p. 3531 - 3535
(2007/10/02)
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