- Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
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Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
- Kumaki, Wataru,Kinoshita, Hidenori,Miura, Katsukiyo
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supporting information
(2022/03/07)
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- Merging shuttle reactions and paired electrolysis for reversible vicinal dihalogenations
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Vicinal dibromides and dichlorides are important commodity chemicals and indispensable synthetic intermediates in modern chemistry that are traditionally synthesized using hazardous elemental chlorine and bromine. Meanwhile, the environmental persistence of halogenated pollutants necessitates improved approaches to accelerate their remediation. Here, we introduce an electrochemically assisted shuttle (e-shuttle) paradigm for the facile and scalable interconversion of alkenes and vicinal dihalides, a class of reactions that can be used both to synthesize useful dihalogenated molecules from simple alkenes and to recycle waste material through retro-dihalogenation. The reaction is demonstrated using 1,2-dibromoethane, as well as 1,1,1,2-tetrachloroethane or 1,2-dichloroethane, to dibrominate or dichlorinate, respectively, a wide range of alkenes in a simple setup with inexpensive graphite electrodes. Conversely, the hexachlorinated persistent pollutant lindane could be fully dechlorinated to benzene in soil samples using simple alkene acceptors.
- Dong, Xichang,Roeckl, Johannes L.,Waldvogel, Siegfried R.,Morandi, Bill
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- Atom-economical brominations with tribromide complexes in the presence of oxidants
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Bromination is an important transformation in organic synthesis, and novel efficient bromination techniques are still required. Herein, we demonstrate atom-economical brominations using (DMI)2HBr3, a novel tribromide complex, with oxidants such as DMSO and Oxone. Using this system, olefinic and aromatic brominations, as well as selective α-monobrominations of ketones proceeded well to afford the desired bromides in good yields. Importantly, in these reactions all of the bromine atoms in this complex are used to brominate.
- Yubata, Kotaro,Matsubara, Hiroshi
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supporting information
p. 1001 - 1004
(2019/03/13)
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- Ph 3 P/I - -Promoted Dichlorination or Dibromination of Epoxides with XCH 2 CH 2 X (X = Cl or Br)
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Ph 3 P/I - -promoted dichlorination and dibromination of epoxides by using XCH 2 CH 2 X (X = Cl or Br) as the halogen source and reaction solvent is described. All reagents are widely available and easy to handle, and mild conditions and operational simplicity make this protocol attractive.
- Long, Jin,Chen, Jia,Li, Rong,Liu, Zhuo,Xiao, Xuan,Lin, Jin-Hong,Zheng, Xing,Xiao, Ji-Chang
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supporting information
p. 181 - 184
(2019/01/14)
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- Alkoxybromination of olefins using ammonium bromide and oxone
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A mild, efficient, and highly regio- and stereoselective method for the methoxy and ethoxy bromination of olefins has been developed using NH 4Br as a bromine source and Oxone as an oxidant. Various kinds of olefins (aromatic, linear, and cyclic olefins) afforded the corresponding alkoxy brominated products in moderate to excellent yields. Taylor & Francis Group, LLC.
- Kumar, Macharla Arun,Naresh, Mameda,Rohitha, Chozhiyath Nappunni,Narender, Nama
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supporting information
p. 3121 - 3129
(2014/01/06)
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- Regio-and stereoselective hydroxybromination and dibromination of olefins using ammonium bromide and oxone
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An efficient protocol for the synthesis of vicinal bromohydrins and dibromides from olefins is presented. Various olefins are regio-and stereoselectively hydroxybrominated and dibrominated with anti fashion, following Markonikov's rule, using eco-friendly, non-toxic, and stable reagents such as NH4Br and oxone in CH3CN/H2O (1:1) and CH3CN without employing catalyst in moderate to excellent yields. Bromohydrins are formed instantaneously.
- MacHarla, Arun Kumar,Chozhiyath Nappunni, Rohitha,Nama, Narender
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supporting information; experimental part
p. 1401 - 1405
(2012/04/04)
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- Facile one-pot synthesis of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent
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A new method for the preparation of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent has been developed. Several α-bromoketones were successfully prepared from a variety of olefins by this method. This procedure is an alternative to conventional molecular bromine.
- Patil, Rajendra D.,Joshi, Girdhar,Adimurthy, Subbarayappa,Ranu, Brindaban C.
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experimental part
p. 2529 - 2532
(2009/09/06)
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- Tetrameric DABCO-bromine: An efficient and versatile reagent for bromination of various organic compounds
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Tetrameric DABCO-bromine is a powerful brominating agent but shows reasonable selectivity with certain substrates. The selective bromination for activated aromatic compounds and alkenes is reported. Synthesis of α-bromo ketones and nitriles has also been achieved by using this reagent and the results are also reported. All products reported were obtained in good to excellent yields.
- Heravi, Majid M.,Derikvand, Fatemeh,Ghassemzadeh, Mitra
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p. 125 - 128
(2007/10/03)
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- Rapid debromination of vic-dibromoalkanes with zinc powder in acetic acid under microwave irradiation
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Microwave irradiation of vic-dibromoalkanes in acetic acid containing zinc powder for 1-2 min gave the corresponding alkenes in high yields.
- Kuang, Chunxiang,Yang, Qing,Senboku, Hisanori,Tokuda, Masao
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p. 282 - 284
(2007/10/03)
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- Micellar Effects upon Alkene Bromination. 2. The Role of Alkene Hydrophobicity
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Surface polarity of cettyltrimethylammonium bromide (CTAB) aqueous micelles was checked by use of as a probe the bromination reaction of a series of 1-alkenes and a water-soluble alkene, cis-4-cyclohexene-1,2-dicarboxylic acid dimethyl ester (I).There was
- Cerichelli, Giorgio,Grande, Celeste,Luchetti, Luciana,Mancini, Giovanna
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p. 3025 - 3030
(2007/10/02)
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- REACTION OF t-BUTYL BROMIDE-DIMETHYL SULPHOXIDE: HALOGENATION AND MIXED HALOGENATION OF MULTIPLE BONDS
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The "t-butyl bromide-Me2SO" reagent brominates alkenes versus alkynes efficiently and selectively.By adding calcium chloride or potassium iodide to the system it is possible to obtain the corresponding dichloro or diiodo derivatives.By adding benzyltriethylammonium chloride to the system, bromochloro derivatives are obtained in good yields.The mechanism of the reactions is discussed.
- Dossena, Arnaldo,Marchelli, Rosangela,Casnati, Giuseppe
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- Polyfunctionalized N-Tensides. VII. Substitution and Elimination in the Reaction of 1,2-Dihalogenoalkanes with Amines
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1,2-Dichloroalkanes, 1,2-Dibromoalkanes and mixtures of 1-bromo-2-chloroalkanes and 1-chloro-2-bromoalkanes react with primary or secondary amines and give both elimination and substitution products, often in a nearly 1:1 proportion.The elimination products are the cis and trans-1-halo-1-alkenes, the 2-halo-1-alkenes, the 1,3- and 2,4-dienes and the 1-alkenes.The main substitution products are the 1,2-bis-aminoalkanes.Physical dates, 1H-n.m.r.-spectra,surface tension values and CMC-dates are given.
- Beger, J.,Meerbote, E.
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