- Catalytic SNAr Hydroxylation and Alkoxylation of Aryl Fluorides
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Nucleophilic aromatic substitution (SNAr) is a powerful strategy for incorporating a heteroatom into an aromatic ring by displacement of a leaving group with a nucleophile, but this method is limited to electron-deficient arenes. We have now established a reliable method for accessing phenols and phenyl alkyl ethers via catalytic SNAr reactions. The method is applicable to a broad array of electron-rich and neutral aryl fluorides, which are inert under classical SNAr conditions. Although the mechanism of SNAr reactions involving metal arene complexes is hypothesized to involve a stepwise pathway (addition followed by elimination), experimental data that support this hypothesis is still under exploration. Mechanistic studies and DFT calculations suggest either a stepwise or stepwise-like energy profile. Notably, we isolated a rhodium η5-cyclohexadienyl complex intermediate with an sp3-hybridized carbon bearing both a nucleophile and a leaving group.
- Kang, Qi-Kai,Li, Ke,Li, Yuntong,Lin, Yunzhi,Shi, Hang,Xu, Lun
-
supporting information
p. 20391 - 20399
(2021/08/13)
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- Bis-selenonium Cations as Bidentate Chalcogen Bond Donors in Catalysis
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Lewis acids are frequently employed in catalysis but they often suffer from high moisture sensitivity. In many reactions, catalysts are deactivated because of the problem that strong Lewis acids also bond to the products. In this research, hydrolytically stable bidentate Lewis acid catalysts derived from selenonium dicationic centers have been developed. The bis-selenonium catalysts are employed in the activation of imine and carbonyl groups in various transformations with good yields and selectivity. Lewis acidity of the bis-selenonium salts was found to be stronger than that of the monoselenonium systems, attributed to the synergistic effect of the two cationic selenonium centers. In addition, the bis-selenonium catalysts are not inhibited by strong bases or moisture.
- He, Xinxin,Wang, Xinyan,Tse, Ying-Lung Steve,Ke, Zhihai,Yeung, Ying-Yeung
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p. 12632 - 12642
(2021/10/21)
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- Linear Paired Electrolysis—Realising 200 % Current Efficiency for Stoichiometric Transformations—The Electrochemical Bromination of Alkenes
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The generation of bromine by oxidation of bromide anions at the anode and reduction of molecular oxygen at the cathode to hydrogen peroxide resulted in the overall formation of two molecules of Br2 (=four electron oxidation) by passing just two electrons through the solution. The bromine was used for the bromination of alkenes and thereby a linear paired electrolysis was attained which resulted in current efficencies of up to 200 %. Also, the diiodination of cyclohexene as well as the electrophilic aromatic bromination of an electron-rich arene were realised both in 168 % current efficiencies.
- Strehl, Julia,Abraham, Marvin L.,Hilt, Gerhard
-
supporting information
p. 9996 - 10000
(2021/03/31)
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- 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
-
supporting information
p. 5977 - 5980
(2021/06/18)
-
- 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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- Cooperativity within the catalyst: alkoxyamide as a catalyst for bromocyclization and bromination of (hetero)aromatics
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Alkoxyamide has been reported as a catalyst for the activation ofN-bromosuccinimide to perform bromocyclization and bromination of a wide range of substrates in a lipophilic solvent, where adequate suppression of the background reactions was observed. The key feature of the active site is the alkoxy group attached to the sulfonamide moiety, which facilitates the acceptance as well as the delivery of bromonium species from the bromine source to the substrates.
- Mondal, Haripriyo,Sk, Md Raja,Maji, Modhu Sudan
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supporting information
p. 11501 - 11504
(2020/10/12)
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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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- Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes
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Photoexcited electron-hole pairs on a semiconductor surface can engage in redox reactions with two different substrates. Similar to conventional electrosynthesis, the primary redox intermediates afford only separate oxidized and reduced products or, more rarely, combine to one addition product. Here, we report that a stable organic semiconductor material, mesoporous graphitic carbon nitride (mpg-CN), can act as a visible-light photoredox catalyst to orchestrate oxidative and reductive interfacial electron transfers to two different substrates in a two- or three-component system for direct twofold carbon–hydrogen functionalization of arenes and heteroarenes. The mpg-CN catalyst tolerates reactive radicals and strong nucleophiles, is straightforwardly recoverable by simple centrifugation of reaction mixtures, and is reusable for at least four catalytic transformations with conserved activity.
- Ghosh, Indrajit,Khamrai, Jagadish,Savateev, Aleksandr,Shlapakov, Nikita,Antonietti, Markus,K?nig, Burkhard
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p. 360 - 366
(2019/08/15)
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- Regioselective bromination of arenes mediated by triphosgene-oxidized bromide
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This article first time describes triphosgene (BTC) as an oxidant while the non-toxic and easy-to-handle potassium bromide (KBr) as the source of bromine to the bromination reaction of aromatic substrates. The novel brominating protocol gives excellent para-regioselectivity of the alkoxyl/hydroxyl arenes and high yield, offering good potential of commercial scale applications. The mechanism of “Triphosgene oxidize bromide” was proposed.
- Xu, Yingzhou,Hu, Dufen,Zheng, Hui,Mei, David,Gao, Zhaobo
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supporting information
(2019/08/30)
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- Copper(II) complexes of a heterotopic N-heterocyclic carbene ligand: Preparation and catalytic application
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Copper complexes containing a N-heterocylic carbene (NHC)/amidate/pyridine tridentate, 3-mesityl-1-(2-oxo-2-[{pyridin-2-ylmethyl}amino]ethyl)-imidazolin-2-ylidene (HL), were synthesized and characterized. By X-ray single crystal analysis, both Cu(L)(OAc) (3a) and Cu(L)Br (3b) show that the metal center is coordinated by a CNN-tridentate and a anionic donor in a slightly distorted square-planar geometry. These copper complexes are active as catalysts for oxidative bromination of dimethoxybenzene and styrene with the use of LiBr as the bromine source and oxygen as the terminal oxidant.
- Aaron Lin, Shih-Chieh,Liu, Yi-Hung,Peng, Shie-Ming,Liu, Shiuh-Tzung
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- Transition-metal-free decarboxylative bromination of aromatic carboxylic acids
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Methods for the conversion of aliphatic acids to alkyl halides have progressed significantly over the past century, however, the analogous decarboxylative bromination of aromatic acids has remained a longstanding challenge. The development of efficient methods for the synthesis of aryl bromides is of great importance as they are versatile reagents in synthesis and are present in many functional molecules. Herein we report a transition metal-free decarboxylative bromination of aromatic acids. The reaction is applicable to many electron-rich aromatic and heteroaromatic acids which have previously proved poor substrates for Hunsdiecker-type reactions. In addition, our preliminary mechanistic study suggests that radical intermediates are not involved in this reaction, which is in contrast to classical Hunsdiecker-type reactivity. Overall, the process demonstrates a useful method for producing valuable reagents from inexpensive and abundant starting materials.
- Quibell, Jacob M.,Perry, Gregory J. P.,Cannas, Diego M.,Larrosa, Igor
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p. 3860 - 3865
(2018/04/26)
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- Pd-Catalyzed Decarboxylative Sonogashira Reaction via Decarboxylative Bromination
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The decarboxylative alkynylation of (hetero)aryl carboxylic acids with terminal alkynes has been achieved by using a Pd(PPh3)4/PCy3 catalyst. This Pd-catalyzed method exhibits good functional group tolerance for both coupling partners and enables chemical modification of complex molecules. The establishment of this decarboxylative alkynylation reaction is attributed to the discovery of a highly selective decarboxylative bromination of (hetero)aryl carboxylic acids with NBS (N-bromosuccinimide).
- Jiang, Quandi,Li, Hongyi,Zhang, Xiaofeng,Xu, Biping,Su, Weiping
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supporting information
p. 2424 - 2427
(2018/04/27)
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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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- Regioselective Halogenation of Arenes and Heterocycles in Hexafluoroisopropanol
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Regioselective halogenation of arenes and heterocycles with N-halosuccinimides in fluorinated alcohols is disclosed. Under mild condition reactions, a wide diversity of halogenated arenes are obtained in good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of one-pot sequential halogenation and halogenation-Suzuki cross-coupling reactions.
- Tang, Ren-Jin,Milcent, Thierry,Crousse, Benoit
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p. 930 - 938
(2018/01/28)
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- Photocatalytic Oxidative Bromination of Electron-Rich Arenes and Heteroarenes by Anthraquinone
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The estimated excited oxidation potential of sodium anthraquinone-2-sulfonate (SAS) increases from 1.8 V to about 2.3 V vs SCE by protonation with Br?nsted acids. This increased photooxidation power of protonated anthraquinone was used for the regio-selective oxidative bromination of electron rich (hetero)arenes and drugs in good yield. The mild reaction conditions are compatible with many functional groups, such as double and triple bonds, ketones, amides and amines, hydroxyl groups, carboxylic acids and carbamates. Mechanistic investigations indicate the photooxidation of the arene followed by nucleophilic bromide addition as the likely pathway. (Figure presented.).
- Petzold, Daniel,K?nig, Burkhard
-
supporting information
p. 626 - 630
(2017/11/22)
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- Atom-Economic Electron Donors for Photobiocatalytic Halogenations
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In vitro cofactor supply and regeneration have been a major obstacle for biocatalytic processes, in particular on a large scale. Peroxidases often suffer from inactivation by their oxidative co-factor. Combining photocatalysis and biocatalysis offers an innovative solution to this problem, but lacks atom economy due to the sacrificial electron donors needed. Herein, we show that redox-active buffers or even water alone can serve as efficient, biocompatible electron sources, when combined with photocatalysis. Mechanistic investigations revealed first insights into the possibilities and limitations of this approach and allowed adjusting the reaction conditions to the specific needs of biocatalytic transformations. Proof-of-concept for the applicability of this photobiocatalytic reaction setup was given by enzymatic halogenations.
- Seel, Catharina Julia,Králík, Antonín,Hacker, Melanie,Frank, Annika,K?nig, Burkhard,Gulder, Tanja
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p. 3960 - 3963
(2018/09/25)
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- One-Pot, Metal-Free Conversion of Anilines to Aryl Bromides and Iodides
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A metal-free synthesis of aryl bromides and iodides from anilines via halogen abstraction from bromotrichloromethane and diiodomethane is described. This one-pot reaction affords aryl halides from the corresponding anilines in moderate to excellent yields without isolation of diazonium salts. The transformation has short reaction times, a simple workup, and insensitivity to moisture and air and avoids excess halogenation. DFT calculations support a SRN1 mechanism. This method represents a convenient alternative to the classic Sandmeyer reaction.
- Leas, Derek A.,Dong, Yuxiang,Vennerstrom, Jonathan L.,Stack, Douglas E.
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supporting information
p. 2518 - 2521
(2017/05/24)
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- Zwitterionic-Salt-Catalyzed Site-Selective Monobromination of Arenes
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A zwitterionic-salt-catalyzed electrophilic monobromination of arenes with high regioselectivity has been developed. Under mild reaction conditions, a wide range of monobrominated aromatic compounds can be obtained in excellent yields. The reaction can be operated using an extremely low catalyst loading (0.05 mol %) with the inexpensive brominating agent N-bromosuccinimide. The versatility of this catalytic protocol has been demonstrated by the scale-up reaction with a 0.01 mol % catalyst loading to provide the selectively halogenated compound in quantitative yield.
- Xiong, Xiaodong,Tan, Fei,Yeung, Ying-Yeung
-
supporting information
p. 4243 - 4246
(2017/08/23)
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- Acid-induced chemoselective arylthiolations of electron-rich arenes in ionic liquids from sodium arylsulfinates: The reducibility of halide anions in [Hmim]Br
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An acid-induced protocol for the chemoselective arylthiolations of electron-rich arenes in ionic liquids from sodium arylsulfinates is introduced. The chemistry, in which [Hmim]Br (heaxylmethylimidazolium bromide) is used as both a solvent and a reducer, provides several advantages including odorless and simple operation, inexpensive reagents, recyclable solvents and gram-scale synthesis.
- Xu, Zhu-Bing,Lu, Guo-Ping,Cai, Chun
-
supporting information
p. 2804 - 2808
(2017/04/04)
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- Decarboxylative Halogenation and Cyanation of Electron-Deficient Aryl Carboxylic Acids via Cu Mediator as Well as Electron-Rich Ones through Pd Catalyst under Aerobic Conditions
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Simple strategies for decarboxylative functionalizations of electron-deficient benzoic acids via using Cu(I) as promoter and electron-rich ones by employing Pd(II) as catalyst under aerobic conditions have been established, which lead to smooth synthesis of aryl halides (-I, Br, and Cl) through the decarboxylative functionalization of benzoic acids with readily available halogen sources CuX (X = I, Br, Cl), and easy preparation of benzonitriles from decarboxylative cyanation of aryl carboxylic acids with nontoxic and low-cost K4Fe(CN)6 under an oxygen atmosphere for the first time.
- Fu, Zhengjiang,Li, Zhaojie,Song, Yuanyuan,Yang, Ruchun,Liu, Yanzhu,Cai, Hu
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p. 2794 - 2803
(2016/04/26)
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- Photocatalytic Selective Bromination of Electron-Rich Aromatic Compounds Using Microporous Organic Polymers with Visible Light
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Pure organic, heterogeneous, metal-free, and visible light-active photocatalysts offer a more sustainable and environmentally friendly alternative to traditional metal-based catalysts. Here we report a series of microporous organic polymers containing photoactive conjugated organic semiconductor units as heterogeneous photocatalysts for a visible-light-promoted, highly selective bromination reaction of electron-rich aromatic compounds using HBr as a bromine source and molecular oxygen as a clean oxidant. Via a simple Friedel-Crafts alkylation reaction, the microporous organic polymers were obtained by cross-linking of organic semiconductor compounds with defined valence and conduction band positions. The utilization of the simply prepared porous polymer-based photocatalytic systems opens new opportunities toward a sustainable and efficient material design for catalysis.
- Li, Run,Wang, Zi Jun,Wang, Lei,Ma, Beatriz Chiyin,Ghasimi, Saman,Lu, Hao,Landfester, Katharina,Zhang, Kai. A. I.
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p. 1113 - 1121
(2016/02/18)
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- Characterization of a Cyanobacterial Haloperoxidase and Evaluation of its Biocatalytic Halogenation Potential
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Vanadium-dependent haloperoxidases (VHPOs) are a class of halogenating enzymes found in fungi, lichen, algae, and bacteria. We report the cloning, purification, and characterization of a functional VHPO from the cyanobacterium Acaryochloris marina (AmVHPO), including its structure determination by X-ray crystallography. Compared to other VHPOs, the AmVHPO features a unique set of disulfide bonds that stabilize the dodecameric assembly of the protein. Easy access by high-yield recombinant expression, as well as resistance towards organic solvents and temperature, together with a distinct halogenation reactivity, make this enzyme a promising starting point for the development of biocatalytic transformations.
- Frank, Annika,Seel, Catharina Julia,Groll, Michael,Gulder, Tanja
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p. 2028 - 2032
(2016/11/09)
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- Efficient and Practical Oxidative Bromination and Iodination of Arenes and Heteroarenes with DMSO and Hydrogen Halide: A Mild Protocol for Late-Stage Functionalization
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An efficient and practical system for inexpensive bromination and iodination of arenes as well as heteroarenes by using readily available dimethyl sulfoxide (DMSO) and HX (X = Br, I) reagents is reported. This mild oxidative system demonstrates a versatile protocol for the synthesis of aryl halides. HX (X = Br, I) are employed as halogenating reagents when combined with DMSO which participates in the present chemistry as a mild and inexpensive oxidant. This oxidative system is amenable to late-stage bromination of natural products. The kilogram-scale experiment (>95% yield) shows great potential for industrial application.
- Song, Song,Sun, Xiang,Li, Xinwei,Yuan, Yizhi,Jiao, Ning
-
supporting information
p. 2886 - 2889
(2015/06/30)
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- Selective Halogenation Using an Aniline Catalyst
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Electrophilic halogenation is used to produce a wide variety of halogenated compounds. Previously reported methods have been developed mainly using a reagent-based approach. Unfortunately, a suitable "catalytic" process for halogen transfer reactions has yet to be achieved. In this study, arylamines have been found to generate an N-halo arylamine intermediate, which acts as a highly reactive but selective catalytic electrophilic halogen source. A wide variety of heteroaromatic and aromatic compounds are halogenated using commercially available N-halosuccinimides, for example, NCS, NBS, and NIS, with good to excellent yields and with very high selectivity. In the case of unactivated double bonds, allylic chlorides are obtained under chlorination conditions, whereas bromocyclization occurs for polyolefin. The reactivity of the catalyst can be tuned by varying the electronic properties of the arene moiety of catalyst.
- Samanta, Ramesh C.,Yamamoto, Hisashi
-
supporting information
p. 11976 - 11979
(2015/08/18)
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- Aerobic photooxidative bromination of aromatic compounds using carbon tetrabromide mediated by anthraquinone-2-carboxylic acid
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We developed the aerobic photooxidative bromination of aromatic compounds using carbon tetrabromide in the presence of anthraquinone-2-carboxylic acid under visible light irradiation.
- Tanaka, Masanori,Kamito, Yuji,Lei, Cui,Tada, Norihiro,Itoh, Akichika
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p. 5886 - 5888
(2015/11/02)
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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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- Brominations with Pr4NBr9 as a solid reagent with high reactivity and selectivity
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Tetrapropylammonium nonabromide (Pr4NBr9) is introduced as a room-temperature solid reagent for rapid bromination reactions of various substrates. The reagent exhibits reactivity similar to that of elemental bromine, but shows higher selectivity and it is easier and safer to store and to handle. Georg Thieme Verlag Stuttgart · New York.
- Beck, Thorsten M.,Haller, Heike,Streuff, Jan,Riedel, Sebastian
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p. 740 - 747
(2014/04/03)
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- HETEROCYCLIC RESORCINOL DERIVATIVES, PREPARATION OF SAME AND COSMETIC USES THEREOF
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The invention relates to a compound of general formula (I) characterized in that: R1 is a C1-C4 alkyl group, andR2 is an optionally substituted nitrogen, sulfur or oxygen containing heteroaromatic ring.
- -
-
Paragraph 0036 - 0038
(2014/03/24)
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- Practical and metal-free electrophilic aromatic halogenation by interhalogen compounds generated in situ from N-halosuccinimide and catalytic TMSCL
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Halomonochloride compounds (ClCl, BrCl, ICl) generated in situ from N-halosuccinimide and catalytic chlorotrimethylsilane (TMSCl, 0.1 equiv) can efficiently halogenate aromatic compounds to give halogenated products in good to excellent yields and selectivities. The reaction can be carried out at room temperature or at lower temperatures, requires only one hour, is practical to apply to a wide range of substrates, and provides a simple access to a variety of haloarene compounds. Georg Thieme Verlag Stuttgart New York.
- Maibunkaew, Tapanee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Bunrit, Anon,Ruchirawat, Somsak
-
supporting information
p. 1769 - 1775
(2014/08/05)
-
- Metal and H2O2 free aerobic oxidative aromatic halogenation with [RNH3+] [NO3-]/HX and [BMIM(SO3H)][NO3)x(X)y] (X = Br, Cl) as multifunctional ionic liquids
-
Novel multifunctional ionic liquids (ILs) are generated by addition of HBr or HCl to alkylammonium nitrates ([RNH3+] [NO 3-]) and to 3-methyl-1-(butyl-4-sulfonyl)imidazolium nitrate ([BMIM(SO3H)][NO3]). The resulting [RNH 3+] [NO3-]/HX and mono (3-methyl-1-(butyl-4-sulfonyl)imidazolium) monohalogenide mononitrate ([BMIM(SO3H)][NO3)x(X)y] (X = Br, Cl)) systems act as solvent and promoter for aerobic oxidative halogenation of arenes under mild conditions in high yields that can be repeated over several cycles.
- Prebil, Rok,Laali, Kenneth K.,Stavber, Stojan
-
supporting information
p. 2108 - 2111
(2013/06/05)
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- Pd(II)-catalyzed bromo- and chlorodecarboxylation of electron-rich arenecarboxylic acids
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A bromo- and chlorodecarboxylation of various aromatic carboxylic acids catalyzed by Pd(II) has been developed in this work. A series of electron-rich arenecarboxylic acids gave the corresponding decarboxylative monohalogenation products under the typical reaction conditions.
- Peng, Xuefeng,Shao, Xiang-Feng,Liu, Zhong-Quan
-
supporting information
p. 3079 - 3081
(2013/07/11)
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- Dicarbaporphyrinoid systems. Synthesis of oxo-adj-dibenziphlorins
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A series of diformylbenzophenones were generated by sequentially reacting protected bromobenzaldehydes with n-butyllithium and ethyl N,N- dimethylcarbamate. The acetal protective groups were cleaved with refluxing formic acid. Vilsmeier-Haack formylation of 2,2′,4,4′- tetramethoxybenzophenone also afforded a related dialdehyde. MacDonald "2 + 2" condensation of three benzophenone dialdehydes with a dipyrrylmethane gave oxophlorin analogues constructed from two benzene and two pyrrole rings. The free base oxodibenziphlorins were rather unstable in solution, and in most cases these porphyrinoids were isolated as the corresponding trifluoroacetate salts. The spectroscopic properties of 6-oxo-adj-dibenziphlorins are consistent with a nonaromatic ring system. DFT calculations indicated that the macrocycles considerably diverge from planarity, particularly when methoxy substituents are present on the arene rings.
- Abusalim, Deyaa I.,Merfeld, Michelle L.,Lash, Timothy D.
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p. 10360 - 10368
(2013/11/06)
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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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- Dihaloiodates(I): Synthesis with hydrogen peroxide and their halogenating activity
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Tetraalkylammonium and pyridinium dichloro- and dibromoiodates(I) were efficiently prepared from iodine and tetralkylammonium chloride or pyridine by oxidation with hydrogen peroxide in the presence of an equimolar amount of a hydrogen halide. Their halogenating activity was tested on 1,3-dimethoxybenzene and styrene as model substrates. The results show that ICl2 - salts acted as iodinating reagents, while IBr2 - salts brominated both substrates. 2012 Elsevier Ltd. All rights reserved.
- Bedra?, Leon,Iskra, Jernej
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p. 5555 - 5558
(2012/11/13)
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- Practical synthesis of aromatic nitriles via gallium-catalysed electrophilic cyanation of aromatic C-H bonds
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A gallium-catalysed, direct cyanation reaction of aromatic and heteroaromatic C-H bonds with cyanogen bromide was developed as a practical synthetic method for the preparation of aromatic nitriles. The Royal Society of Chemistry 2012.
- Okamoto, Kazuhiro,Watanabe, Masahito,Murai, Masahito,Hatano, Ryo,Ohe, Kouichi
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supporting information; scheme or table
p. 3127 - 3129
(2012/04/23)
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- PROCESS FOR PRODUCTION OF OXIDATION REACTION PRODUCT OF AROMATIC COMPOUND
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The present invention provides a process for producing an oxidation reaction product of an aromatic compound, having excellent environmental load reduction performance, cost reduction performance, etc. Provided is a process for producing an oxidation reaction product of a raw material aromatic compound by reacting the raw material aromatic compound with an oxidizing agent. The process further uses an electron donor-acceptor linked molecule. The process includes the step of: reacting the electron donor-acceptor linked molecule in an electron-transfer state, the oxidizing agent, and the raw material aromatic compound, thereby generating an oxidation reaction product resulting from oxidation of the raw material aromatic compound.
- -
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Page/Page column 18
(2012/07/14)
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- A Green protocol for the bromination and iodination of the aromatic compounds using H5IO6/NaBr and H5IO 6/NaI in the water
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Bromination and iodination of the aromatic compounds have efficiently been carried out at room temperature and 70 °C, respectively, in short reaction times using orthoperiodic acid/sodium bromide (1:2) and orthoperiodic acid/sodium iodide (1:2) in water to prepare the corresponding halo compounds with excellent yields.
- Yousefi-Seyf, Jaber,Tajeian, Kazem,Kolvari, Eskandar,Koukabi, Nadiya,Khazaei, Ardeshir,Zolfigol, Mohammad Ali
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p. 2619 - 2622
(2012/10/29)
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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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- Simple and improved regioselective brominations of aromatic compounds using N-benzyl-N,N-dimethylanilinium peroxodisulfate in the presence of potassium bromide under mild reactions conditions
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A simple, efficient, and mild method for the selective bromination of some activated aromatic compounds using N-benzyl-N,N-dimethylanilinium peroxodisulfate in the presence of potassium bromide in non-aqueous solution is reported. The results obtained revealed good to excellent selectivity between the ortho and para positions of phenols and methoxyarenes.
- Ghasemnejad-Bosra, Hassan,Ramzanian-Lehmali, Farhad,Jafari, Somaye
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experimental part
p. 685 - 692
(2012/01/16)
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- Chemo-and regioselective bromination of aromatic compounds in the presence of γ-picolinium bromochromate (γ-PBC)/CH3CN
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Regioselective oxidative bromination of activated aromatic compounds has been studied using γ-Picolinium bromochromate in either CH3COOH or CH3CN is reported. The results obtained revealed excellent yields of monobromo compounds at para-position under thermal condition especially in methyl cyanide.
- Mahmoodi,Yazdanbakhsh,Hassanzadeh
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experimental part
p. 429 - 434
(2012/04/04)
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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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- Regioselective SNAr reactions of substituted difluorobenzene derivatives: practical synthesis of fluoroaryl ethers and substituted resorcinols
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In this Letter, we describe a practical and highly selective method for the preparation of fluoroaryl ethers and differentially substituted resorcinol derivatives. This synthetic strategy relies on a selective SNAr of substituted difluorobenzen
- Ouellet, Stéphane G.,Bernardi, Anna,Angelaud, Remy,O'Shea, Paul D.
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supporting information; experimental part
p. 3776 - 3779
(2009/10/11)
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- Total synthesis of psoralidin, an anticancer natural product
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A base-catalyzed condensation of phenyl acetate with acid chloride, followed by intramolecular cyclization and microwave-assisted cross-metathesis reaction, leads to the first total synthesis of psoralidin, a natural product with a broad range of biological activities, in a highly convergent and regioselective manner.
- Pahari, Pallab,Rohr, Juergen
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body text
p. 2750 - 2754
(2009/08/15)
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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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- Direct halogenation of organic compounds with halides using oxone in water - A green protocol
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Direct bromination and iodination of various aromatic compounds with NaBr and NaI using oxone (2KHSO5·KHSO4·K 2S04) in water was accomplished successfully in high-to-excellent yields. The main benefit of this protocol is the performance of the reactions in water in the presence of a harmless oxidant without the use of any organic cosolvents. Using NaBr and NaI as the safe sources of halogens is another advantage of the protocol. This method is easily applicable to the large-scale operations. We have also applied this method successfully for the iodocyclization of an unsaturated alcohol and an unsaturated carboxylic acid.
- Firouzabadi,Iranpoor,Kazemi
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experimental part
p. 1675 - 1681
(2010/01/29)
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- Highly efficient halogenation of organic compounds with halides catalyzed by cerium(III) chloride heptahydrate using hydrogen peroxide as the terminal oxidant in water
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In this article a new environmentally friendly catalytic method is described for the efficient monoiodination and bromination of arenes and also iodoetherification and iodolactonization of olefins using hydrogen peroxide as the terminal oxidant. The method is based on using sodium iodide or sodium bromide, hydrogen peroxide (35%) and cerium(III) chloride as an effective catalyst in water at room temperature or under reflux conditions. By this protocol, iodination of anilines proceeded with high regioselectivity at the para position with the formation of small amounts of the ortho isomers. However, bromination of anilines proceeded with absolute regioselectivity to give the para isomers as the sole products in high yields. Iodinations and bromi-nations of m-xylene, toluene, chloro- and bromobenzenes were proceeded with excellent regioselectivity to produce the para isomers as the sole products. Benzene was also halogenated by this catalytic system to give the monohalogenated benzene in good yields. Iodoetherification and iodolactonization of olefins also proceeded easily in high yields at room temperature. However, the bromination of olefins by this protocol failed and the starting materials were detected intact.
- Firouzabadi, Habib,Iranpoor, Nasser,Kazemi, Somayeh,Ghaderi, Arash,Garzan, Atefeh
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experimental part
p. 1925 - 1932
(2011/03/18)
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- Regioselective copper-catalyzed chlorination and bromination of arenes with O2 as the oxidant
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Electron-rich aromatic C-H bonds undergo regioselective chlorination and bromination in the presence of CuX2, LiX (X = Cl, Br) and molecular oxygen. Preliminary mechanistic insights suggest that the bromination and chlorination reactions proceed by different pathways.
- Yang, Lujuan,Lu, Zhan,Stahl, Shannon S.
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supporting information; experimental part
p. 6460 - 6462
(2010/03/04)
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- A new method for halogenation of aromatic compounds by using dimethyldioxirane and tetrabutylammonium halides
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In this presentation the novel regioselective halogenation of arenes or phenols with dimethyldioxirane and Bu4NX is described. The results showed that a new, versatile and mild method can be utilized for preparation of aryl halides starting with arenes or phenols. Finally, this aryl halide forming methodology is applicable to structurally more complex flavonoids.
- Lee, Yean-Jang,Wu, Huan-Ting,Lin, Chia-Ning
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experimental part
p. 585 - 587
(2010/04/23)
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- Double helix formation of oligoresorcinols in water: Thermodynamic and kinetic aspects
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We previously reported that the oligoresorcinols formed double-stranded helices in neutral water through interstrand aromatic interactions. In the present study, we synthesized a new series of oligomers from the 2merto the 15mer to explore the thermodynamics, kinetics, and mechanism of the double helix formation of the oligoresorcinols in water. The double helix formation was dependent on the chain length of the oligomers and s ignificantly affected by solvent, pH, salt, and temperature. The free energy change (-?G) for the double helix formation linearly increased withthe chain length from the 4mer to the 11mer (ΔΔG = -0.94 kc al mol-1 unit-1), whereas it did not change for the oligomers longer than the 11 mer. The van't Hoff analysis of the 9mer revealed that the double helix formation was an enthalpically driven process (ΔH = -27 ± 1.5 kcal mol-1 and ΔS = -70 ± 5 cal mol-1 K-1), which was consistentwith the upfield shifts in the 1H NMR spectra and the hypoch romicity of the absorption spectra as a result of the interstrand aromatic interactions in water. Furthermore, the kinetic analysis of the chainexchange reaction between the double helices of the optically active an d optically inactive 11mers revealed a small ΔS?, suggesting that the chain exchange proceeds not via the dissociation-association pathway, but via the direct exchange pathway.
- Goto, Hidetoshi,Furusho, Yoshio,Miwa, Kazuhiro,Yashima, Eiji
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scheme or table
p. 4710 - 4719
(2009/09/26)
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- Bromination of some aromatic compounds with potassium bromide in the presence of benzyltriphenylphosphonium peroxodisulfate
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A simple, efficient, and mild method for selective bromination of some activated aromatic compounds using potassium bromide in the presence of benzyltriphenylphosphonium peroxodisulfate in nonaqueous solution is reported. The results obtained revealed good to excellent selectivity between ortho and para positions of phenols and methoxyarenes. Copyright Taylor & Francis Group, LLC.
- Tajik, Hassan,Mohammadpoor-Baltork, Iraj,Albadi, Jalal
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p. 323 - 328
(2007/10/03)
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