- A Practical Procedure for Regioselective Bromination of Anilines
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A highly practical procedure for the preparation of bromoanilines by using copper-catalyzed oxidative bromination has been developed. Treatment of free anilines with readily available NaBr and Na 2S 2O 8in the presence of a catalytic amount of CuSO 4·5H 2O enabled regioselective bromination.
- Takahashi, Yusuke,Seki, Masahiko
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p. 1828 - 1832
(2021/04/15)
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- Method of catalytically synthesizing polybromo-aniline in water phase
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The invention discloses a method of catalytically synthesizing polybromo-aniline in a water phase. The method comprises following steps: adding a catalytic amount of a free radical initiator, aniline derivatives, cheap and low-toxic bromine salts, and water into a reactor; carrying out reactions in a photocatalytic reaction instrument under power of 5W at a room temperature; after a while, extracting the reaction product by ethyl acetate, and carrying out recrystallization to obtain polybromo-aniline; wherein the free radical initiator is eosin, sodium persulfate, or potassium persulfate. The power of the incandescent lamp of the photocatalytic reaction instrument is 5W. The free radical initiator and bromine salts are cheap and easily available. The method is an ideal synthesis method of polybromo-aniline. Cheap and low-toxic bromine salts are used to replace liquid bromine. The cheap and easily available free radical initiator is used to replace unstable and explosive hydrogen peroxide. After 4 to 10 hours of reactions under the power of 5W, polybromo-aniline can be synthesized, the yield and the reaction selectivity are high, the byproducts are few, and the post treatment is simple.
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Paragraph 0012; 0022
(2019/10/04)
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- Making endo-cyclizations favorable again: A conceptually new synthetic approach to benzotriazoles via azide group directed lithiation/cyclization of 2-azidoaryl bromides
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Although benzotriazoles are important and ubiquitous, currently there is only one conceptual approach to their synthesis: bridging the two ortho-amino groups with an electrophilic nitrogen atom. Herein, we disclose a new practical alternative-the endo-cyclization of 2-azidoaryl lithiums obtained in situ from 2-azido-aryl bromides. The scope of the reaction is illustrated using twenty-four examples with a variety of alkyl, alkoxy, perfluoroalkyl, and halogen substituents. We found that the directing effect of the azide group allows selective metal-halogen exchange in aryl azides containing several bromine atoms. Furthermore, (2-bromophenyl)diazomethane undergoes similar cyclization to give an indazole. Thus, cyclizations of aryl lithiums containing an ortho-X = Y = Z group emerge as a new general approach for the synthesis of aromatic heterocycles. DFT computations suggested that the observed endo-selectivity applies to the anionic cyclizations of other functionalities that undergo "1,1-additions" (i.e., azides, diazo compounds, and isonitriles). In contrast, cyclizations with the heteroatomic functionalities that follow the "1,2-addition" pattern (cyanates, thiocyanates, isocyanates, isothiocyanates, and nitriles) prefer the exo-cyclization path. Hence, such reactions expand the current understanding of stereoelectronic factors in anionic cyclizations.
- Ageshina, Alexandra A.,Chesnokov, Gleb A.,Topchiy, Maxim A.,Alabugin, Igor V.,Nechaev, Mikhail S.,Asachenko, Andrey F.
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supporting information
p. 4523 - 4534
(2019/05/17)
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- Graphene Oxide Promoted Oxidative Bromination of Anilines and Phenols in Water
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The mildly acidic and oxidative nature of graphene oxide, with its large surface area available for catalytic activity, has been explored in aromatic nuclear bromination chemistry for the first time. The versatile catalytic activity of graphene oxide (GO) has been used to selectively and rapidly brominate anilines and phenols in water. The best results were obtained at ambient temperatures using molecular bromine in a protocol promoted by oxidative bromination catalyzed by GO; these transformations proceeded with 100% atom economy with respect to bromine and high selectivities for the tribromoanilines and -phenols. Reduced graphene oxide (r-GO) was observed to form after the second recycle (third use) of GO. This technique is also effective with N-bromosuccinimide (NBS) as the brominating reagent. In the case of NBS, reactions were instantaneous and the GO displayed excellent recyclability without any loss of activity over several cycles.
- Ghorpade, Prashant Vasantrao,Pethsangave, Dattatray Appasha,Some, Surajit,Shankarling, Ganapati Subray
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p. 7388 - 7397
(2018/07/29)
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- 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane: An efficient and high oxygen content oxidant in various oxidative reactions
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Several oxidative approaches namely thiocyanation of aromatic compounds, epoxidation of alkenes, amidation of aromatic aldehydes, epoxidation of α β-unsaturated ketones, oxidation of sulfides to sulfoxides and sulfones, bayer-villeger reaction, bromination and iodation of aniline and phenol derivatives oxidative esterification, oxidation of pyridines and oxidation of secondary, allylic and benzyllic alcohols were carried out using 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as the potential solid oxidant which can be stored for several months without any loss in its activity. All of the procedures were accomplished via mild reaction conditions and the products were afforded in high yields and short reaction times.
- Khosravi, Kaveh,Naserifar, Shirin
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supporting information
p. 6584 - 6592
(2018/10/05)
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- Identification of bromination products of chloro-substituted anilines in aqueous environment by gas chromatography
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To reduce the detection limits of aniline and its various chloroderivatives (all isomers of mono- and dichloroanilines, 2,4,5 -, 2,4,6-, and 3,4,5-trichloroanilines, pentachloroaniline) in aqueous media we suggested bromination reaction, followed by gas chromatographic definition bromo derivatives of chloroanilines on a selective electron capture detector. To identify the products of bromination of chloroaniline in combination with mass-spectrometric data we used chromatographic retention indices on standard nonpolar polydimethylsiloxane stationary phase that was determined for 50 compounds in this class. The technique of identifying bromoderivatives of chloroaniline in water was developed at the gas-chromatographic analysis in the selective electron capture detector. To improve the reliability of the identification of additional bromoderivatives of chloroanilines we obtained their trifluoroacetyl derivatives.
- Gruzdev,Filippova,Zenkevich,Kondratenok
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experimental part
p. 1748 - 1759
(2012/02/15)
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- Effect of structural factors and solvent nature in bromination of anilines
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Reaction of electrophilic bromination of aniline containing various ortho, meta, and para substituents in the aromatic ring was studied. The optimal conditions for synthesis of mono-, di-, tri-, and tetrabromo derivatives of aniline and brominated analog of Aniline Black were found.
- Bagmanov
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experimental part
p. 1570 - 1576
(2011/06/20)
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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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- 2,4,6-Halogeno-aniline derivatives
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The title compounds, 2,4-dibromo-6-chloroaniline, C6H4-Br2ClN, (1), N-acetyl-4-bromo-2,6-dichloroaniline (alternative name: 4′-bromo-2′,6′-dichloroacetanilide), C8H6-BrCl2NO, (2), and N-formyl-4-bromo-2,6-difluoroaniline [alternative name: N-(4-bromo-2,6-difluorophenyl)formamide], C7H4BrF2NO, (3), all have at least one short cell axis (in the range 4.2-4.7 A) and contain molecules which are linked to form infinite chains along the short-axis directions via N-H...N or N-H...O hydrogen bonds. Compound (1) has halogen disorder at the 2 and 6 positions.
- Ferguson, George,Low, John N.,Penner, Glenn H.,Wardell, James L.
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p. 1974 - 1977
(2007/10/03)
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- Synthesis of 2,6-disubstituted and 2,3,6-trisubstituted anilines
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A number of 2,6-disubstituted and 2,3,6-trisubstituted anilines have been prepared via the selective para dehalogenation of the corresponding anilines. Modification of the substituents on the amino nitrogen demonstrates that the selectivity is derived from steric rather than electronic effects. The effects of the choice of formate hydrogen donor, Pd catalyst, solvent, and temperature upon the efficiency and selectivity of the dehalogenation are discussed.
- Pews,Hunter,Wehrmeyer
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p. 4809 - 4820
(2007/10/02)
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