- Stepwise mechanism for the bromination of arenes by a hypervalent iodine reagent
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A mild, metal-free bromination method of arenes has been developed using the combination of bis(trifluoroacetoxy)iodobencene and trimethylsilyl bromide. In situ-formed dibromo(phenyl)-λ3-iodane (PhIBr2) is proposed as the reactive intermediate. This methodology using PIFA/TMSBr has been applied with success to a great number of substrates (25 examples). The treatment of mono-substituted activated arenes led to para-brominated products (2u-z) in excellent 83-96% yields. Density functional theory calculations indicate a stepwise mechanism involving a double bromine addition followed by a type II dyotropic reaction with concomitant re-aromatization of the six-membered ring.
- Arrieta, Ana,Cossío, Fernando P.,Granados, Albert,Shafir, Alexandr,Vallribera, Adelina
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p. 2142 - 2150
(2020/03/11)
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- Catalyst and Additive-Free Direct Amidation/Halogenation of Tertiary Arylamines with N-haloimide/amides
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An approach has been developed for the amidation (halogenation) of tertiary arylamines by electrophilic activation using N-haloimide/amides. Several control experiments have been performed, and the coupling reaction outcomes indicated that the N-haloimide/amide brings three major functions, including electrophilic activation, aromatic halogenation and nucleophilic nitrogen sources. This cascade reaction features simple manipulation, requires no additional catalyst, oxidant or additives, and is performed under mild conditions. (Figure presented.).
- Xu, Xiu-Juan,Amuti, Adila,Wusiman, Abudureheman
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supporting information
p. 5002 - 5008
(2020/10/06)
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- Method for preparing bromo reagent by oxidative bromination reaction and method for further preparing bromine-containing compound
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The invention relates to a method, and for preparing a bromine-containing compound through a reaction, of a :electron-substituted furan compound.rich electron-substituted furan compound, rich in an electron-rich substituted thiophene compound: The substituent of,rich electron-substituted furan compound containing, of an electron-rich substituted furan compound . The method for preparing the bromine-containing compound by the reaction of the present invention comprises the following steps. preparing an electron-rich substituted furan), compound (by). reacting with a bromine, containing substituted phenyl group, (.rich, electron-substituted furan compound and an aromatic or unsaturated bond-containing compound with an electron-rich substituted furan compound containing an electron-rich substituted furan compound.
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Paragraph 0032-0033
(2020/03/17)
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- Electrochemical Regioselective Bromination of Electron-Rich Aromatic Rings Using n Bu 4 NBr
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Electrochemical regioselective bromination of electron-rich aromatic rings using stoichiometric tetrabutylammonium bromide (n Bu 4 NBr) has been accomplished under mild conditions. This protocol provides an environmentally friendly and simple way for the construction of C-Br bond in moderate to high yields with wide functional group tolerance.
- Bai, Ya,Che, Xin,Liu, Nian,Ning, Shulin,Shi, Lingling,Wang, Shutao,Wang, Siyu,Xiang, Jinbao,Xie, Wenxia
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supporting information
p. 1313 - 1316
(2019/06/20)
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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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p. 1001 - 1004
(2019/03/13)
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- Synthesis of Halogenated Anilines by Treatment of N, N-Dialkylaniline N-Oxides with Thionyl Halides
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The special reactivity of N,N-dialkylaniline N-oxides allows practical and convenient access to electron-rich aryl halides. A complementary pair of reaction protocols allow for the selective para-bromination or ortho-chlorination of N,N-dialkylanilines in up to 69% isolated yield. The generation of a diverse array of halogenated anilines is made possible by a temporary oxidation level increase of N,N-dialkylanilines to the corresponding N,N-dialkylaniline N-oxides and the excision of the resultant weak N-O bond via treatment with thionyl bromide or thionyl chloride at low temperature.
- Reed, Hayley,Paul, Tyler R.,Chain, William J.
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p. 11359 - 11368
(2018/08/06)
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- A quick, mild and efficient bromination using a CFBSA/KBr system
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Bromination is a fundamental transformation in organic chemistry and brominated compounds as building blocks are of paramount importance in organic synthesis. In our study, we have developed an efficient method of bromination by using a CFBSA/KBr system at room temperature in a short reaction time. Notably, this approach has been proven to be applicable to a range of substrates including 1,3-diketones and β-keto esters, phenols, aromatic amines and heteroarenes with good to excellent yields.
- Jiang, Pan-Pan,Yang, Xian-Jin
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p. 90031 - 90034
(2016/10/09)
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- Regioselective bromination of organic substrates by LDH-CO3 2--Br- promoted by V2O5-H 2O2
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An efficient, fast, simple, mild, and selective monobromination of aromatic compounds, with high para-selectivity, is reported. The catalytic system is readily prepared from a Mg-Al-layered double hydroxide-CO3 2--Br- (LDH-CO32--Br-) as the source of bromide, V2O5 as a promoter and hydrogen peroxide as the oxidant. The use of hydrogen peroxide as a synthetically useful oxidizing agent is reported for generating electrophilic bromine in situ from easily available KBr as a bromine source, to brominate electron rich aromatic compounds, employing LDH-CO32--Br3- as the phase-transfer catalyst. The phase-transfer catalyst leads to nearly complete bromination in 3 h at room temperature with high selectivity. The reaction rate of p-bromoanisole and p-bromotoluene formation by LDH-CO 32--Br3- in a triphasic system was studied. The heterogeneity of the reaction system facilitates the recovery and recycling of the catalyst, and the reagent components are environmentally acceptable. The catalyst, LDH-CO32--Br3 -, and its precursors, LDH-CO32--Br- and LDH-CO32-, were characterized by powder XRD, FT-IR and UV-vis spectroscopy.
- Ghiaci,Sedaghat,Ranjbari,Gil
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experimental part
p. 18 - 26
(2011/01/05)
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- A novel tunable aromatic bromination method using alkyl bromides and sodium hydride in DMSO
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Aromatic bromination on various aromatic systems with different substitutions was performed in the presence of alkyl bromide and sodium hydride in DMSO. Mono-bromination on a wide range of substrates was achieved by selecting proper alkyl bromides and controlling its amount. Further bromination could happen with more active alkyl bromides and additional amount of bromides and sodium hydride. The yields ranged from moderate to excellent. In addition, reaction mechanism was postulated to explain our observations.
- Guo, MaoJun,Varady, Laszlo,Fokas, Demosthenes,Baldino, Carmen,Yu, Libing
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p. 3889 - 3892
(2007/10/03)
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- 1-Benzyl-4-aza-1-azoniabicyclo[2.2.2] octane tribromide as a highly reactive brominating agent for aniline derivatives
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Reaction of anilines with 1-benzyl-4-aza-1-azoniabicyclo[2.2.2]octane tribromide (3) in the presence of CaCO3 in small amounts of methanol gave brominated aromatic amines in good yields at room temperature. The isolation of products is straightforward.
- Hajipour,Imanieh,Pourmousavi
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p. 4597 - 4604
(2007/10/03)
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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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- (Diacetoxyiodo)benzene-Lithium Bromide as a Convenient Electrophilic Br+ Source
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A mild and versatile procedure for the bromination of olefins and activated arenes by in situ generation of 'Br+' using (diacetoxyiodo)benzene and lithium bromide is presented. The reactions were carried out in open vessels at room temperature and were typically complete in 30 minutes. The brominated products were isolated by column chromatography, which also allowed for the isolation of the iodobenzene by-product for recycle.
- Braddock, D. Christopher,Cansell, Gemma,Hermitage, Stephen A.
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p. 461 - 464
(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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- AROMATIC TERTIARY AMINES AND n-BUTYL NITRITE
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The reaction between alkyl nitrites, particularly n-butyl nitrite, and tertiary aromatic amines under a variety of experimental conditions promptly yielded products of N-dealkylation-N-nitrosation, ring nitration, ipso-substitution and, occasionally, combinations of these processes.Aminoethers were detected as final products and intermediates on the way to N-nitrosations.Reaction pathways are suggested for some of the observed behaviours on the basis of experimental evidences whereas other alternatives are discarded.
- Varardo, Giancarlo,Giumanini, Angelo G.,Strazzolini, Paolo
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p. 4303 - 4332
(2007/10/02)
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- Aminobenzenes, XVII. Addition Products of N,N-Dialkylanilines and Bromine - Synthesis and Reactions
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4-Bromo-N,N-dialkylanilines 1 react with bromine in inert solvents to give the 1:1 addition compounds 2 or 3.IR and UV investigations established the structure of the isolated products to be CT complexes (? complexes) for 2 and N-bromoanilinium bromides for 3.The adducts 2 react to yield substitution products 6 and dealkylation products 7 in polar solvents (dimethylformamide, acetic acid, methanol), whereas the main product from 2a by reaction in acetone is N,N,N',N'-tetramethylbenzidine (9).Radical cations 10 are postulated to be the determining intermediates for these reactions.The tendency of the alkyl groups to be cleaved off decreases in the order isopropyl > ethyl > methyl.Under analogous conditions the N-bromo compounds 3 give predominantly the anilines 1 and only small amounts of substitution products 6, dealkylation and reaction to benzidines were not observed.
- Effenberger, Franz,Steinbach, Adalbert,Epple, Gerhard,Hanauer, Johann
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p. 3539 - 3551
(2007/10/02)
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- Alkyl Nitrite-Metal Halide Deamination Reactions. 7. Synthetic Coupling of Electrophilic Bromination with Substitutive Deamination for Selective Synthesis of Multiply Brominated Aromatic Compounds from Arylamines
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Aromatic amines undergo substitution with copper(II)bromide that is in competition with substitutive deamination when these reactions are performed with tert-butyl nitrite.Except for the exceptionally reactive 4-substituted 1-aminonaphthalenes,which undergo selective bromine substitution at the 1- and 2-positions in relatively high isolated yields,rates for oxidative bromination and substitutive deamination are not sufficiently different that selective multiple bromination can be achieved.Oxidative bromination of N,N-dimethylaniline by copper(II)bromide occurs with partial dealkylation,and nitration products are observed from reactions performed with copper(II)bromide and tert-butyl nitrite.Implications of these results for the successful utilization of copper(II)bromide/tert-butyl nitrite combinations in substitutive deamination reactions of aromatic amines are discussed.Multiply brominated aromatic compounds are produced from aromatic amines in high yield through treatment of the aromatic amine with the combination of molecular bromine and catalytic quantities of copper(II)bromide and,following a normally brief time delay,with tert-butyl nitrite.All unsubstituted aromatic ring positions ortho and para to the amino group,as well as the position of the amino group,are substituted by bromine.The only observed byproducts from use of this procedure (usually 2percent yield) are the partially brominated benzene derivatives.
- Doyle, Michael P.,Lente, Michael A. van,Mowat, Rex,Fobare, William F.
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p. 2570 - 2575
(2007/10/02)
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