- Halogenated method of aromatic compound
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The invention belongs to the field of organic synthesis, and particularly relates to synthesis of aromatic halogens, in particular to arylamine. The invention discloses a synthesis method of a corresponding ortho-halogenated product from aromatic compounds such as carbazole and phenol. The method comprises the following steps: adding a metal sulfonate salt catalyst, aromatic amine, carbazole, phenol and other hydrogen - heteroatom-containing aromatic compound reaction substrates, a halogenation reagent and a reaction solvent at a specific reaction temperature. After the drying agent is dried, the yield of the reaction product and the nuclear magnetic characterization determining structure are determined by column chromatography. The reaction product yield is determined by gas chromatography. By adopting the method, under the cheap metal salt catalyst, a plurality of ortho-substituted brominated and chloro products can be obtained with moderate to excellent yield.
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Paragraph 0211-0213
(2021/11/10)
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- Directed regioselectiveortho,ortho′-magnesiations of aromatics and heterocycles usingsBu2Mg in toluene
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Aryl azoles are ubiquitous as bioactive compounds and their regioselective functionalization is of utmost synthetic importance. Here, we report the development of a toluene-soluble dialkylmagnesium basesBu2Mg. This new reagent allows mild and regioselectiveortho-magnesiations of variousN-arylated pyrazoles and 1,2,3-triazoles as well as arenes bearing oxazoline, phosphorodiamidate or amide directing groups. The resulting diarylmagnesium reagents were further functionalized either by Pd-catalyzed arylation or by trapping reactions with a broad range of electrophiles (aldehydes, ketones, allylic halides, acyl chlorides, Weinreb amides, aryl halides, hydroxylamine benzoates, terminal alkynes). Furthermore, several doubleortho,ortho′-magnesiations were realized in the case of aryl oxazolines,N-aryl pyrazoles as well as 2-aryl-2H-1,2,3-triazoles by simply repeating the magnesiation/electrophile trapping sequence allowing the preparation of valuable 1,2,3-functionalized arenes.
- Doerrich, Sabrina B.,Hess, Andreas,Karaghiosoff, Konstantin,Knochel, Paul,Lemaire, Sébastien,Lutter, Ferdinand H.,Prohaska, Jan P.,Trauner, Florian,Wagschal, Simon
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p. 8424 - 8429
(2021/07/02)
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- A convenient and efficient H2SO4-promoted regioselective monobromination of phenol derivatives using N-bromosuccinimide
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A convenient, rapid H2SO4-promoted regioselective monobromination reaction with N-bromosuccinimide was developed. The desired para-monobrominated or ortho-monobrominated products of phenol derivatives were obtained in good to excellent yields with high selectivity. Regioselective chlorination and iodination were also achieved in the presence of H2SO4 using N-chlorosuccinimide and N-iodosuccinimide, respectively.
- Wu, Yong-Qi,Lu, Hai-Jia,Zhao, Wen-Ting,Zhao, Hong-Yi,Lin, Zi-Yun,Zhang, Dong-Feng,Huang, Hai-Hong
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supporting information
p. 813 - 822
(2020/02/15)
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- Catalyst-Controlled Regioselective Chlorination of Phenols and Anilines through a Lewis Basic Selenoether Catalyst
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We report a highly efficient ortho-selective electrophilic chlorination of phenols utilizing a Lewis basic selenoether catalyst. The selenoether catalyst resulted in comparable selectivities to our previously reported bis-thiourea ortho-selective catalyst, with a catalyst loading as low as 1%. The new catalytic system also allowed us to extend this chemistry to obtain excellent ortho-selectivities for unprotected anilines. The selectivities of this reaction are up to >20:1 ortho/para, while the innate selectivities for phenols and anilines are approximately 1:4 ortho/para. A series of preliminary studies revealed that the substrates require a hydrogen-bonding moiety for selectivity.
- Dinh, Andrew N.,Maddox, Sean M.,Vaidya, Sagar D.,Saputra, Mirza A.,Nalbandian, Christopher J.,Gustafson, Jeffrey L.
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p. 13895 - 13905
(2020/11/03)
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- Bioinspired catalysis and bromoperoxidase like activity of a multistimuli-responsive supramolecular metallogel: Supramolecular assembly triggered by pi-pi stacking and hydrogen bonding interactions
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We report the synthesis and characterization of a new self-assembled VO2-L metallogel. Gel formation was investigated by dissolving VO2-L in various solvents and it was found that water/methanol (1?:?9 (v/v) ratio) induces gel formation. The single crystal X-ray structure of the VO2-L metallogel exhibits C-H?O and N-H?O hydrogen bonding interactions and pi-pi stacking. The VO2-L xerogel obtained after removing the solvents was found to exhibit outstanding performance in catalysis. Bromoperoxidase-like activity of the VO2-L metallogel was also reported. The present catalytic studies are simple and proceed under mild conditions.
- Kurbah, Sunshine Dominic,Lal, Ram A.
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p. 5410 - 5418
(2020/04/17)
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- Regioselective monobromination of phenols with KBr and ZnAl–BrO3?–layered double hydroxides
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The regioselective mono-bromination of phenols has been successfully developed with KBr and ZnAl–BrO3?–layered double hydroxides (abbreviated as ZnAl–BrO3?–LDHs) as brominating reagents. The para site is much favorable and the ortho site takes the priority if para site is occupied. This reaction featured with excellent regioselectivity, cheap brominating reagents, mild reaction condition, high atom economy, broad substrate scope, and provided an efficient method to synthesize bromophenols.
- Wang, Ligeng,Feng, Chun,Zhang, Yan,Hu, Jun
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supporting information
(2020/02/22)
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- Practical, mild and efficient electrophilic bromination of phenols by a new I(iii)-based reagent: The PIDA-AlBr3 system
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A practical electrophilic bromination procedure for phenols and phenol-ethers was developed under efficient and very mild reaction conditions. A broad scope of arenes was investigated, including the benzimidazole and carbazole core as well as analgesics such as naproxen and paracetamol. The new I(iii)-based brominating reagent PhIOAcBr is operationally easy to prepare by mixing PIDA and AlBr3. Our DFT calculations suggest that this is likely the brominating active species, which is prepared in situ or isolated after centrifugation. Its stability at 4 °C after preparation was confirmed over a period of one month and no significant loss of its reactivity was observed. Additionally, the gram-scale bromination of 2-naphthol proceeds with excellent yields. Even for sterically hindered substrates, a moderately good reactivity is observed.
- Satkar, Yuvraj,Ramadoss, Velayudham,Nahide, Pradip D.,García-Medina, Ernesto,Juárez-Ornelas, Kevin A.,Alonso-Castro, Angel J.,Chávez-Rivera, Ruben,Jiménez-Halla, J. Oscar C.,Solorio-Alvarado, César R.
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p. 17806 - 17812
(2018/05/28)
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- o-xylylene bis(triethyl ammonium tribromide) as a mild and recyclable reagent for rapid and regioselective bromination of anilines and phenols
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Background: o-Xylylene bis(triethyl ammonium tribromide) (OXBTEATB) as a recyclable and high bromine containing di-(tribromide) reagent has been employed for the bromination of various organic substrates such as phenol and aniline or its derivatives. This catalyst can be recovered and reused several times. Methods: Aryl bromides shown in Table 1, were easily produced from bromination of aromatic compounds by OXBTEATB. This high-yield process lets the reagents to be recycled and reused. Results: As shown in Table 1, substituted anilines, phenols and β-naphthol were found to be the most reactive and immediately converted to the corresponding mono-brominated products by OXBTEATB. Conclusion: OXBTEATB can be considered a solidified bromine. This novel reagent has variable solubility in different polar protic and aprotic solvents but insoluble in non-polar aprotic solvent. Subsequently, OXBTEATB can be recognized as a more useful brominating and regioselective catalyst than the liquid bromine.
- Hemati, Roya,Shahvelayati, Ashraf S.,Yadollahzadeh, Khadijeh
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p. 682 - 687
(2018/07/14)
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- Synthesis, kinetics, and mechanism of bromophenols by N-bromophthalimide in aqueous acetic acid
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The kinetics and mechanism of bromination of phenol and its substituents, viz. 4-chlorophenol, 4-bromophenol, 4-methylphenol, and 4-methoxyphenol by N-bromophthalimide (NBP) in the presence of mercuric acetate in the temperature range of 303–318?K in aqueous acetic acid medium have been investigated. The reaction follows first-order dependence on [NBP] and fractional order dependence of rate on [Phenol]. The activation parameters have been evaluated, and based on the observed kinetic results the probable mechanism has been proposed. Observed kinetic features and Hammett's reaction constant (ρ) suggests that bromination occurs through electrophilic substitution of bromonium ion (Br+) into the aromatic ring in the transition state. Large negative entropy of activation values probably suggests the rigid nature of transition state.
- Anjaiah, Birla,Prameela, Kethavath,Srinivas, Pabba,Rajanna, Kamatala Chinna
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p. 804 - 812
(2018/09/11)
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- Expedient Access to 2-Benzazepines by Palladium-Catalyzed C?H Activation: Identification of a Unique Hsp90 Inhibitor Scaffold
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Bioactive 2-benzazepines were accessed in an atom- and step-economical manner through a versatile palladium-catalyzed C?H activation strategy. The C?H arylation required low catalyst loading and a mild base, which was reflected by a broad scope and high functional-group tolerance. The benzotriazolodiazepinones were identified as new heat shock protein 90 (Hsp90) inhibiting lead compounds, with considerable potential for anti-cancer applications.
- Virelli, Matteo,Moroni, Elisabetta,Colombo, Giorgio,Fiengo, Lorenzo,Porta, Alessio,Ackermann, Lutz,Zanoni, Giuseppe
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supporting information
p. 16516 - 16520
(2018/10/25)
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- Isoquinolinium Dichromate and Chlorochromate as Efficient Catalysts for Oxidative Halogenation of Aromatic Compounds under Acid-Free Conditions
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Isoquinolinium dichromate and isoquinolinium chlorochromate were found as efficient catalysts to trigger oxidative bromination and iodination of aromatic hydrocarbons with KBr/KI and KHSO4 under acid-free conditions. Reaction times reduced highly significantly under sonication, followed by corresponding mono bromo derivatives in very good yield with high regioselectivity.
- Rao, A. Sambashiva,Rajanna,Reddy, K. Rajendar,Kulkarni, Subhash
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p. 832 - 837
(2016/02/12)
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- An efficient and chemoselective deprotection of aryl tert-butyldimethylsilyl (TBDMS) ethers by NaCN
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Phenolic tert-butyldimethylsilyl (TBDMS) ethers can be deprotected to yield phenols in excellent yield using sodium cyanide (NaCN) as catalyst in ethanol. The deprotectation of various phenolic TBDMS ethers were found to be very convenient, fast, high yielding and chemoselective.
- Qiao, Xue-Jun,Hou, Xiao,Fang, Wu-Hong,Bao, Xue-Fei,Chen, Guo-Liang
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p. 899 - 904
(2016/05/19)
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- Ligand-free, palladium-catalyzed dihydrogen generation from TMDS: Dehalogenation of aryl halides on water
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A mild and environmentally attractive dehalogenation of functionalized aryl halides has been developed using nanoparticles formed from PdCl2 in the presence of tetramethyldisiloxane (TMDS) on water. The active catalyst and reaction medium can be recycled. This method can also be applied to cascade reactions in a one-pot sequence.
- Bhattacharjya, Anish,Klumphu, Piyatida,Lipshutz, Bruce H.
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supporting information
p. 1122 - 1125
(2015/03/14)
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- Visible-light photoredox catalysis enabled bromination of phenols and alkenes
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A mild and efficient methodology for the bromination of phenols and alkenes has been developed utilizing visible light-induced photoredox catalysis. The bromine was generated in situ from the oxidation of Br- by Ru(bpy)33+, both of which resulted from the oxidative quenching process.
- Zhao, Yating,Li, Zhe,Yang, Chao,Lin, Run,Xia, Wujiong
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p. 622 - 627
(2014/04/17)
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- Green, mild and efficient bromination of aromatic compounds by HBr promoted by trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane in water as a solvent
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A combination of HBr and trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxolane as a new and powerful oxidant was found effective for facile bromination of different aromatic compounds at room temperature in water as a green solvent. Mild reaction conditions, high selectivity and yield, high reaction rate and non-toxicity are some of the major advantages of this synthetic protocol.
- Khosravi, Kaveh,Kazemi, Samira
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experimental part
p. 387 - 390
(2012/05/20)
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- MCM-41-supported oxo-vanadium(IV) complex: A highly selective heterogeneous catalyst for the bromination of hydroxy aromatic compounds in water
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An ecofriendly solid catalyst has been synthesized by anchoring vanadium(IV) into organically modified MCM-41. First, the surface of Si-MCM-41 was modified with 3-aminopropyl-triethoxysilane (3-APTES), the amine group of which upon condensation with ortho-hydroxy-acetophenone affords a N 2O2-type Schiff base moiety in the mesoporous matrix. The Schiff base moieties were used to anchor oxo-vanadium(IV) ions. The prepared catalyst has been characterized by UV-vis, IR spectroscopy, small-angle X-ray diffraction (SAX), nitrogen sorption, and transmission electron microscopy (TEM) studies. It is observed that the mesostructure has not been destroyed in the multistep synthesis procedure, as evidenced by SAX and TEM measurements. The catalyst has shown unprecedented high conversion as well as para selectivity toward the bromination of hydroxy aromatic compounds using aqueous 30% H 2O2/KBr in water. The reaction proceeds according to the stoichiometric ratio, and the monobrominated product was obtained as the major product using a stoichiometric amount of the bromine source. The immobilized complex does not leach or decompose during the catalytic reactions, showing practical advantages over the free metal complex.
- Bhunia, Susmita,Saha, Debraj,Koner, Subratanath
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experimental part
p. 15322 - 15329
(2012/04/11)
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- Facile p-toluenesulfonic acid-promoted para-selective monobromination and chlorination of phenol and analogues
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para-Regioselective bromination of phenol and analogues, promoted by p-toluenesulfonic acid, is achieved in high to excellent yields at room temperature with N-bromosuccinimide. Chlorination with N-chlorosuccinimide and catalysed by p-toluenesulfonic acid also gives para-chlorinated phenol analogues in good yields at room temperature. para-Bromination of phenol, promoted by p-toluenesulfonic acid, is achieved in excellent yields at room temperature with N-bromosuccinimide. p-Toluenesulfonic acid is also effective as a promoter of para-chlorination with N-chlorosuccinimide.
- Bovonsombat, Pakorn,Ali, Rameez,Khan, Chiraphorn,Leykajarakul, Juthamard,Pla-On, Kawin,Aphimanchindakul, Suraj,Pungcharoenpong, Natchapon,Timsuea, Nisit,Arunrat, Anchalee,Punpongjareorn, Napat
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experimental part
p. 6928 - 6935
(2010/10/01)
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- Vanadium-catalyzed oxidative bromination promoted by Br?nsted acid or Lewis acid
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The oxidative bromination of arenes was induced by a vanadium catalyst in the presence of a bromide salt and a Br?nsted acid or a Lewis acid under molecular oxygen, which provides an eco-friendly bromination method as compared with a conventional bromination one with bromine. This catalytic reaction could be applied to the bromination of alkenes and alkynes to give the corresponding vic-bromides. Use of aluminum halide as a Lewis acid in place of a Br?nsted acid was demonstrated to provide a more practical protocol for the oxidative bromination. From ketones, α-bromination products were obtained. AlBr3 was found to serve as both a bromide source and a Lewis acid to induce the bromination smoothly. 51V NMR experiment showed that this catalytic bromination is likely to depend on the redox cycle of a vanadium catalyst under molecular oxygen.
- Kikushima, Kotaro,Moriuchi, Toshiyuki,Hirao, Toshikazu
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experimental part
p. 6906 - 6911
(2010/09/18)
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- An efficient copper-catalysed aerobic oxybromination of arenes in water
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An aerobic oxybromination of arenes catalysed by Cu(NO3) 2 was achieved using HBr as a bromine source, molecular oxygen as the oxidant and water as solvent with high selectivity. The catalyst shows not only high chemoselectivity for monobromination, but also a remarkable regioselectivity for para-isomers.
- Wang, Jian,Wang, Wei,Li, Jing-Hua
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supporting information; experimental part
p. 2124 - 2126
(2011/02/24)
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- Regioselective bromination of aromatic amines and phenols using N-benzyl-DABCO tribromide
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N-Benzyl-DABCO tribromide, a stable, solid organic ammonium tribromide, has been used as a bromine source for the regioselective and high-yielding bromination of aromatic amines and phenols. Mono-bromination proceeds well in the presence of a stoichiometric amount of bromine source at room temperature.
- Moghaddam, Firouz Matloubi,Zargarani, Dordaneh
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experimental part
p. 4212 - 4220
(2010/01/08)
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- Vilsmeier-haack bromination of aromatic compounds with KBr and N-bromosuccinimide under solvent-free conditions
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Bromination of aromatic hydrocarbons is triggered by Vilsmeier-Haack reagent [N,N-dimethyl formamide (DMF-POCl3 system)] in the presence of KBr or N-bromosuccinimide (NBS) under solvent-free conditions by grinding the reactants in a mortar with a pestle. The reactions afforded corresponding bromo derivatives in very good yield with high regioselectivity. The results are comparable with those obtained under reflux conditions. Copyright Taylor & Francis Group, LLC.
- Chakradhar,Roopa,Rajanna,Saiprakash
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experimental part
p. 1817 - 1824
(2009/10/02)
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- Regioselective, photochemical bromination of aromatic compounds using N-bromosuccinimide
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Regioselective nuclear bromination of aromatic compounds is investigated with N-bromosuccinimide as the brominating agent under UV irradiation to afford the corresponding brominated compounds. The reaction proceeds at ambient temperature (30 ± 2 °C) without any catalyst. In most of the reactions, regioselectively mono-brominated products are obtained in good to high yields. The conversion and selectivity for bromination depend on the nature of the substituent on the aromatic ring.
- Chhattise, Prakash K.,Ramaswamy,Waghmode, Suresh B.
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p. 189 - 194
(2008/03/30)
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- Regioselective monobromination of substituted phenols in the presence of β-cyclodextrin
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Cyclodextrin acts as a restricting nanovessel to enhance regioselectivity in bromination of substituted phenols such as 3-nitrophenol, 2-chlorophenol, 3-chlorophenol, and 4-chlorophenol. In contrast to solution bromination, cyclodextrin facilitates regioselective monobromination and formation of polybrominated products are substantially reduced. Selectivities in brominations are also observed in water and in the solid state. The observed results are rationalized on the basis of specific modes of inclusion of substituted phenols inside the cyclodextrin cavity and find strong support from energy minimization studies and 1H-1H NOESY.
- Suresh, Palaniswamy,Annalakshmi, Subramanian,Pitchumani, Kasi
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p. 4959 - 4967
(2008/02/02)
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- A convenient and regioselective oxidative bromination of electron-rich aromatic rings using potassium bromide and benzyltriphenylphosphonium peroxymonosulfate under nearly neutral reaction conditions
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Regioselective oxidative bromination of electron-rich aromatic rings has been studied using potassium bromide as a bromine source in the presence of benzyltriphenylphosphonium peroxymonosulfate as oxidant under nearly neutral reaction conditions. In most cases we obtained monobrominated derivatives regioselectively and in good to high yields without the aid of strong acids.
- Adibi, Hadi,Hajipour, Abdol R.,Hashemi, Majid
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p. 1255 - 1259
(2007/10/03)
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- {[K.18-Crown-6]Br3}n: a unique tribromide-type and columnar nanotube-like structure for the oxidative coupling of thiols and bromination of some aromatic compounds
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Reaction of 18-crown-6 with KBr and then with bromine (Br2) afforded a unique tribromide salt with a nanotube-like structure ({[K.18-crown-6]Br3}n). Oxidative coupling of thiols and bromination of some aromatic compounds is the first report on the chemistry of this reagent.
- Zolfigol, Mohammad Ali,Chehardoli, Gholamabbas,Salehzadeh, Sadegh,Adams, Harry,Ward, Michael D.
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p. 7969 - 7973
(2008/03/14)
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- Kinetics and mechanism of bromination of phenols by sodium bromate-sodium bisulphite reagent in water-acetonitrile mixture
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Kinetics of bromination of phenols with HOBr produced in situ from sodium bromate-sodium bisulphite reagent has been studied in water-acetonitrile mixture iodometrically. The order of the reaction is found to be unity in [HOBr] and fractional in [phenol]. HOBr has been established as the effective brominating species. A mechanism involving a six-membered cyclic adduct between phenol and HOBr, which decomposes in a slow step has been proposed. Thermodynamic parameters for the formation of adduct and the activation parameters for the first order decomposition of the adduct have been evaluated and discussed. The influence of the substituents on the first order decomposition rate constant (k/s-1) of the adduct has been discussed. The sole reaction product has been identified as the corresponding o-bromophenol.
- Viroopakshappa,Jagannadham
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p. 532 - 534
(2007/10/03)
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- The Synthesis of 5-Substituted 2,3-Dihydrobenzofurans
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The preparation of 2,3-dihydrobenzofurans 6 from 2-(2-bromophenoxy)ethyl chlorides 3 by reaction with magnesium in a development of the Parham cyclialkylation reaction is described.A high yielding procedure using phase-transfer catalysis has also been developed for the preparation of the intermediate chloroethyl ethers 3 from bromophenols 2.The 5-hydroxy derivative 15 may be obtained from 2,3-dihydrobenzofuran (6a) by reaction with electrophilic reagents followed by oxidation.
- Alabaster, Ramon J.,Cottrell, Ian F.,Marley, Hugh,Wright, Stanley H. B.
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p. 950 - 952
(2007/10/02)
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- Kinetics and Mechanism of Bromination of Phenols by N-Bromoacetamide: Effect of Substituents on Decomposition of Intermediate Adduct
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Rates of reactions of phenol and substituted phenols with HOBr, produced in situ by the hydrolysis of N-bromoacetamide (NBA) are measured in aqueous methanol iodometrically in the presence of excess acetamide (AA).A mechanism involving an intermediate six-membered cyclic transition state between phenol and HOBr (formation constant K) which decomposes in a slow step with a rate constant (k) has been proposed.Activation/thermodynamic parameters for all the steps, i.e. k, K and Kh (Kh is the hydrolysis constant of NBA) have been evaluated in the temperature range 303 to 323 K and discussed.The sole reaction product has been identified as the corresponding o-bromophenol.
- Venkateshwarlu, S.,Jagannadham, V.
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p. 314 - 317
(2007/10/02)
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