- Dibrominated addition and substitution of alkenes catalyzed by Mn2(CO)10
-
A practical method for the dibromination of alkenes without using molecular bromine is consistently appealing in organic synthesis. Herein, we report Mn-catalyzed dibrominated addition and substitution of alkenes only with N-bromosuccinimide, producing a variety of synthetically valuable dibrominated compounds in moderate to high yields. This journal is
- Chan, Albert S. C.,Jiang, Yi,Meng, Shanshui,Song, Xianheng,Zhang, Hong,Zou, Yong
-
supporting information
p. 13385 - 13388
(2021/12/17)
-
- A General Method for the Dibromination of Vicinal sp3C-H Bonds Exploiting Weak Solvent-Substrate Noncovalent Interactions
-
A general procedure of 1,2-dibromination of vicinal sp3 C-H bonds of arylethanes using N-bromosuccinimide as the bromide reagent without an external initiator has been established. The modulation of the strength of the intermolecular noncovalent interactions between the solvent and arylethane ethanes, quantitatively evaluated via quantum chemical calculations, allows us to circumvent the fact that arylethane ethane cannot be dibrominated through traditional methods. The mechanism was explored by both experiments and quantum chemical calculations, revealing a radical chain with HAA process.
- Qi, Zaojuan,Li, Weihe,Niu, Yanning,Benassi, Enrico,Qian, Bo
-
supporting information
p. 2399 - 2404
(2021/03/03)
-
- Electrochemical Synthesis of O-Phthalimide Oximes from α-Azido Styrenes via Radical Sequence: Generation, Addition and Recombination of Imide-N-Oxyl and Iminyl Radicals with C?O/N?O Bonds Formation
-
Electrochemically induced radical-initiated reaction of vinyl azides with N-hydroxyphthalimide resulting O-phthalimide oximes with challenging for organic chemistry N?O-N fragment has been discovered. The developed approach introduces in synthesis electrochemically generated O-centered imide-N-oxyl radicals as the coupling components. Sequential formation of C?O and N?O bonds was achieved via generation and selective addition of imide-N-oxyl radicals, followed by recombination with iminyl radicals. A wide range of O-phthalimide oximes was obtained with the yields up to 84percent. (Figure presented.).
- Paveliev, Stanislav A.,Churakov, Artem I.,Alimkhanova, Liliya S.,Segida, Oleg O.,Nikishin, Gennady I.,Terent'ev, Alexander O.
-
supporting information
p. 3864 - 3871
(2020/07/30)
-
- Mild and Efficient Vicinal Dibromination of Olefins Mediated by Aqueous Ammonium Fluoride
-
A mild and efficient vicinal dibromination of olefins has been developed by using saturated aqueous ammonium fluoride solution as the promoter. Inexpensive and commercially available N -bromosuccinimide (NBS) was used as the brominating reagent. The corresponding vicinal dibromoalkanes could be obtained in good to excellent yields.
- Ng, Wing Hin,Shing, Tony K. M.,Yeung, Ying-Yeung
-
supporting information
p. 419 - 424
(2018/02/23)
-
- A Highly Efficient Method for the Bromination of Alkenes, Alkynes and Ketones Using Dimethyl Sulfoxide and Oxalyl Bromide
-
The pairing of DMSO and oxalyl bromide is reported as a highly efficient brominating reagent for various alkenes, alkynes and ketones. This bromination approach demonstrates remarkable advantages, such as mild conditions, low cost, short reaction times, provides excellent yields in most cases and represents a very attractive alternative for the preparation of dibromides and α-bromoketones.
- Ding, Rui,Li, Jiaqi,Jiao, Wenyi,Han, Mengru,Liu, Yongguo,Tian, Hongyu,Sun, Baoguo
-
p. 4325 - 4335
(2018/11/21)
-
- A bromo-capped diruthenium(i,i) N-heterocyclic carbene compound for in situ bromine generation with NBS: Catalytic olefin aziridination reactions
-
A bromo-capped metal-metal bonded diruthenium(i,i) complex Ru2(CO)4(PIN)2Br2 (1) (PIN = 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene) generates bromine with N-bromosuccinimide (NBS) at room temperature. Cycloalkene and stilbene are readily brominated by stoichiometric reactions with 1 and NBS. An analysis of the dibrominated products suggests the formation of cyclic bromonium intermediates indicating in situ Br2 generation. Complex 2, an iodide analogue of 1, is also synthesized. The reaction of 2 with N-iodosuccinimide releases I2, which is confirmed by the starch-iodine test. The catalytic utility of 1 is examined for the bromination of phenol. Catalyst 1, in combination with NBS and base, exhibits regioselectivity towards monobrominated products. Furthermore, efficient olefin aziridination is demonstrated utilizing catalyst 1 in the presence of NBS, K2CO3 and TsNH2.
- Sengupta, Gargi,Pandey, Pragati,De, Subhabrata,Ramapanicker, Ramesh,Bera, Jitendra K.
-
p. 11917 - 11924
(2018/09/10)
-
- Electrochemical bromination of cyclic and acyclic enes using biphasic electrolysis
-
A simple method of electrochemical bromination of a series of cyclic and acyclic enes (styrene and substituted styrenes, stilbene, indene, and cyclooctene) in a biphasic water-chloroform mixture mediated by bromide/bromine redox system is reported. Aqueous 25% NaBr/H2SO4 is used as the electrolyte. Regio- and stereoselective dibromination of enes is achieved. Moderate to excellent yields of the product (83-98%) is obtained depending on the substrate. Electrolyte reuse has also been demonstrated successfully using HBr in the dibromination of styrene.
- Kulangiappar,Ramaprakash,Vasudevan,Raju
-
supporting information
p. 145 - 153
(2016/02/23)
-
- Bromination of olefins with HBr and DMSO
-
A simple and inexpensive methodology is reported for the conversion of alkenes to 1,2-dibromo alkanes via oxidative bromination using HBr paired with dimethyl sulfoxide, which serves as the oxidant as well as cosolvent. The substrate scope includes 21 olefins brominated in good to excellent yields. Three of six styrene derivatives yielded bromohydrins under the reaction conditions.
- Karki, Megha,Magolan, Jakob
-
p. 3701 - 3707
(2015/04/22)
-
- An optimised procedure for PTFE phase vanishing reactions: An improved reaction design and the use of reagents adsorbed on silica
-
While the phase-vanishing (PV)-PTFE reaction design works well with a broad range of substrates and reaction conditions, there are occasional problems. A description of the problems and their importance, including their effects on the reaction outcome and ways to address them, are discussed. Details of an improved design, a hybrid of previously reported PV-PTFE and solvent-free PV-PTFE designs, is presented, as well as the use of silica-supported reagents.
- Parsons, Brendon A.,Smith, Olivia Lin,Dragojlovic, Veljko
-
p. 574 - 581
(2015/11/27)
-
- Visible-light photoredox catalysis enabled bromination of phenols and alkenes
-
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
-
p. 622 - 627
(2014/04/17)
-
- Polystyrene bound dioxidovanadium(V) complexes of 2-acetylpyridine derived ligands for catalytic oxidations
-
Three neat complexes [VVO2(acpy-bhz)] (1) [V VO2(acpy-inh)] (2) and [VVO2(acpy- nah] (3) and the corresponding polymer-supported (PS) dioxidovanadium(V) complexes having monobasic tridentat
- Maurya, Mannar R.,Chaudhary, Nikita,Kumar, Amit,Avecilla, Fernando,Costa Pessoa, Jo?o
-
-
- Polymer and non-polymer-grafted dioxidomolybdenum(VI) complexes having ONO donor ligand and their catalytic activities for the oxidative bromination of organic substrates
-
The ligand H2sal-iah (I), derived from salicylaldehyde and indole-3-acetic hydrazide, reacts with [MoVIO2(acac) 2] in methanol to give dioxidomolybdenum(VI) complex [Mo VIO2(sal-iah)(MeOH)]
- Maurya, Mannar R.,Kumar, Naveen,Avecilla, Fernando
-
-
- Polymer-grafted and neat vanadium(V) complexes as functional mimics of haloperoxidases
-
The monobasic tridentate ONN donor ligand 1-(2-pyridylazo)-2-naphthol [Hpan (I)] reacts with [VIVO(acac)2] in dry methanol to yield the oxidovanadium(IV) complex [VIVO(acac)(pan)] (1). The dioxidovanadium(V) complex [{VVO(pan)}2(μ-O) 2] (2) is obtained by aerial oxidation of 1 in methanol. Complex 2 can also be prepared directly by reacting [VIVO(acac)2] with I followed by aerial oxidation in methanol. Treatment of 1 or 2 in methanol with H2O2 yields the oxidomonoperoxidovanadium(V) complex [VVO(O2)(pan)(MeOH)] (3). Reaction of imidazolomethylpolystyrene cross-linked with 5% divinylbenzene (PS-im) with 2 in DMF resulted in the formation of the polymer-grafted dioxidovanadium(V) complex PS-im[VVO2(pan)] (4). All these complexes are characterized by various spectroscopic techniques (IR, electronic, NMR ( 1H and 51V) and electron paramagnetic resonance (EPR)), thermal, field-emission scanning electron micrographs (FE-SEM) as well as energy dispersive X-ray (EDX) studies. The crystal and molecular structure of 3 has been determined, confirming the ONN binding mode of I. The polymer-grafted complex 4 has been used for the oxidative bromination of styrene, salicylaldehyde and trans-stilbene. Various parameters, such as amounts of catalyst, oxidant (aqueous 30% H2O2), KBr and aqueous 70% HClO4 have been optimized to obtain the maximum oxidative bromination of the substrates. Under the optimized reaction conditions, styrene gave a maximum of 99% conversion after 2 h of reaction, with the main products having a selectivity order of: 1-phenylethane-1,2-diol (75%) > 2-bromo-1- phenylethane-1-ol (20%) > 1,2-dibromo-1-phenylethane (1.2%). With nearly same conversion in same time, the oxidative bromination of salicylaldehyde gave three products with the selectivity order: 5-bromosalicylaldehyde > 2,4,6-tribromophenol > 3,5-dibromosalicylaldehyde. A maximum of 91% conversion of trans-stilbene has been obtained in 2 h of reaction time, where selectivity of the obtained reaction products varied in the order: 2,3-diphenyloxirane (trans-stilbene oxide) > 1,2-dibromo-1,2-diphenylethane > 2-bromo-1,2-diphenylethanol. The catalytic activity of the non-polymer grafted complex 2 is lower than that of the polymer-grafted one. In addition, the recycling ability of the grafted complex makes it better over the neat complex.
- Maurya, Mannar R.,Chaudhary, Nikita,Avecilla, Fernando
-
p. 436 - 448
(2013/11/19)
-
- Direct sustainable bromination of alkenes in aqueous media and basic ionic liquids
-
Electron-rich and electron-poor alkenes have been dibrominated using a rapid and sustainable procedure. The reactions were conducted in aqueous medium and basic ionic liquids which catalyzed the direct addition of bromine. The protocol leads to remarkable results, high yields under mild conditions, complete chemo- and stereo-selectivity and allows the recycling of ionic liquids, reducing costs, and environmental impact.
- Primerano, Patrizia,Cordaro, Massimiliano,Scala, Angela
-
p. 4061 - 4063
(2013/07/25)
-
- Magnetic-nanoparticle-supported 2,2′-bis[3-(triethoxysilyl)propyl] imidazolium-substituted diethyl ether bis(tribromide): A convenient recyclable reagent for bromination
-
A new magnetic-nanoparticle-supported bromination reagent was synthesized by anchoring a 2,2′-bis[3-(triethoxysilyl)propyl]imidazolium-substituted diethyl ether bis(tribromide) onto the surface of γ-Fe2O 3 nanoparticles and subsequently treating this new ionic liquid with bromine. The nanoparticle reagent was obtained with good loading levels and has been successfully used for the efficient bromination of a wide range of alkenes, alkynes, ketones, and aromatic substrates. More importantly, the reagent could be easily recovered by an external magnet and reused six times without significant loss of activity. A new maghemite nanoparticle bromination reagent has been prepared. The nanoparticle reagent was obtained with good loading levels and has been successfully used for the efficient bromination of a wide range of alkenes, alkynes, ketones, and aromatic substrates. Copyright
- Wu, Liqiang,Yin, Zhikui
-
p. 6156 - 6163
(2014/01/06)
-
- Alkoxybromination of olefins using ammonium bromide and oxone
-
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
-
supporting information
p. 3121 - 3129
(2014/01/06)
-
- Synthesis of acetylenes via dehydrobromination using solid anhydrous potassium phosphate as the base under phase-transfer conditions
-
Phase-transfer catalyzed preparation of acetylenes from the corresponding vicinal dibromo compounds via double dehydrobromination using the mild solid base, anhydrous potassium phosphate, under very mild conditions is reported.
- Shenawi-Khalil, Sanaa,Sonavane, Sachin U.,Sasson, Yoel
-
experimental part
p. 2295 - 2297
(2012/07/27)
-
- Brominated methanes as photoresponsive molecular storage of elemental Br2
-
The photochemical generation of elemental Br2 from brominated methanes is reported. Br2 was generated by the vaporization of carbon oxides and HBr through oxidative photodecomposition of brominated methanes under a 20 W low-pressure mercury lamp, wherein the amount and situations of Br2 generation were photochemically controllable. Liquid CH 2Br2 can be used not only as an organic solvent but also for the photoresponsive molecular storage of Br2, which is of great technical benefit in a variety of organic syntheses and in materials science. By taking advantage of the in situ generation of Br2 from the organic solvent itself, many organobromine compounds were synthesized in high practical yields with or without the addition of a catalyst. Herein, Br2 that was generated by the photodecomposition of CH2Br2 retained its reactivity in solution to undergo essentially the same reactions as those that were carried out with solutions of Br2 dissolved in CH 2Br2 that were prepared without photoirradiation. Furthermore, HBr, which was generated during the course of the photodecomposition of CH2Br2, was also available for the substitution of the OH group for the Br group and for the preparation of the HBr salts of amines. Furthermore, the photochemical generation of Br2 from CH2Br2 was available for the area-selective photochemical bleaching of natural colored plants, such as red rose petals, wherein Br2 that was generated photochemically from CH 2Br2 was painted onto the petal to cause radical oxidations of the chromophoric anthocyanin molecules. The generation of Br 2 from brominated methanes occurred upon photoirradiation under O2. The solutions that contained elemental Br2 were useful for the synthesis of organobromine compounds and the macroscopic photochemical bleaching of colored plants. Copyright
- Kawakami, Kazumitsu,Tsuda, Akihiko
-
p. 2240 - 2252
(2012/11/06)
-
- Verification of stereospecific dyotropic racemisation of enantiopure d and l-1,2-dibromo-1,2-diphenylethane in non-polar media
-
The first example of a dyotropic rearrangement of an enantiomerically pure, conformationally unconstrained, vicinal dibromide confirms theoretical predictions: d and l-1,2-dibromo-1,2-diphenylethane racemise stereospecifically in refluxing benzene without crossover to the meso-isomer. An orbital analysis of this six-electron pericyclic process is presented.
- Christopher Braddock,Roy, Debjani,Lenoir, Dieter,Moore, Edward,Rzepa, Henry S.,Wu, Judy I-Chia,Von Rague Schleyer, Paul
-
supporting information
p. 8943 - 8945
(2012/11/13)
-
- Regio-and stereoselective hydroxybromination and dibromination of olefins using ammonium bromide and oxone
-
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
-
supporting information; experimental part
p. 1401 - 1405
(2012/04/04)
-
- Visible-light photoredox catalysis: Dehalogenation of vicinal dibromo-, α-halo-, and α,α-dibromocarbonyl compounds
-
vic-Dibromo-, α-halo-, or α,α-dibromocarbonyl compounds can be efficiently dehalogenated using catalytic tris(2,2′-bipyridyl) ruthenium dichloride (Ru(bpy)3Cl2) in combination with 1,5-dimethoxynaphthalene (DMN) and ascorbate as sacrificial electron donor. For this process, a visible light promoted photocatalytic cycle is proposed that involves the reduction of carbon halogen bonds via free radical intermediates.
- Maji, Tapan,Karmakar, Ananta,Reiser, Oliver
-
supporting information; experimental part
p. 736 - 739
(2011/03/20)
-
- Efficient one-pot synthesis of 2-arylbenzo[b]furans from 2-styrylphenols using CuBr2
-
A new route to the synthesis of 2-arylbenzo[b]furans has been developed. It involves homo/cross-McMurry coupling of salicylaldehyde/substituted salicylaldehydes/aromatic aldehydes to 2-styrylphenols, which undergo intramolecular cyclization with CuBr
- Bhatt, Suchitra,Roy, Kshama,Nayak, Sandip K.
-
body text
p. 2736 - 2746
(2010/10/21)
-
- Organocatalytic diastereoselective dibromination of alkenes
-
A highly diastereoselective pyrrolidine-promoted dibromination of alkenes by combination of NBS and succinimide is presented. The pyrrolidine-mediated dibromination of alkenes is higly anti-selective and gives the corresponding products in moderate to high yields and up to >25:1 dr.
- Zhu, Mingzhao,Lin, Shuangzheng,Zhao, Gui-Ling,Sun, Junliang,Córdova, Armando
-
experimental part
p. 2708 - 2712
(2010/07/04)
-
- Sequential bromination reactions from beads with methyltriphenylphosphonium tribromide groups
-
A reusable bromination reagent based on polystyrene beads with covalently appended methyltriphenylphosphonium tribromide groups has been developed. The results from bromination reactions of several structurally diverse unsaturated substrates with the beads and with solutions of a non-polymeric model brominating reagent, methyltriphenylphosphonium tribromide, are described. It is shown that the reactions are highly regio- and stereo-selective and can be conducted easily. Copyright
- Cristiano, Rodrigo,Walls, Andrew D.,Weiss, Richard G.
-
supporting information; experimental part
p. 904 - 909
(2011/09/14)
-
- Efficient bromination of alkenes and alkynes using potassium bromide and diacetoxy iodobenzene
-
Bromination of alkenes and alkynes has efficiently been carried out at room temperature in short reaction times using KBr and diacetoxy iodobenzene in CH2Cl2-H2O (1:1) to prepare the corresponding trans-dibromo compounds in excellent yields. Copyright Taylor & Francis Group, LLC.
- Das, Biswanath,Srinivas, Yallamalla,Sudhakar, Chittaluri,Damodar, Kongara,Narender, Ravirala
-
experimental part
p. 220 - 227
(2009/04/07)
-
- Selective aerobic oxidative dibromination of alkenes with aqueous HBr and sodium nitrite as a catalyst
-
Various alkenes (internal, terminal, aryl and alkyl substituted) and 1,2-diphenylethyne were efficiently and selectively dibrominated using 2 equivalents of 48% aqueous hydrobromic acid, with air as an oxidant and sodium nitrite as a catalyst. Despite the presence of water, only trans dibromination occurred producing anti-1,2-dibromoalkanes and (E)-1,2-dibromo-1,2- diphenylethene. A comparison of resource demand, waste production and environmental, health and safety issues of the NaNO2 catalyzed aerobic bromination with molecular bromine and other oxidative bromination methods revealed that the proposed method is not only selective and effective but has a better environmental profile.
- Podgorsek, Ajda,Eissen, Marco,Fleckenstein, Jens,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
-
experimental part
p. 120 - 126
(2010/04/22)
-
- Solvent-free phase-vanishing reactions with PTFE (Teflon) as a phase screen
-
In a solvent-free phase-vanishing reaction with PTFE (polytetrafluoroethylene, Teflon) tape as the phase screen, a thermometer adapter is utilized to insert a PTFE-sealed tube into the vapor phase above the substrate. Besides avoiding use of solvents, the experimental design is not dependent upon the densities of the reactants and the procedure generates little or no waste while providing the reaction products in high yield and in high purity.
- Pels, Kevin,Dragojlovic, Veljko
-
scheme or table
(2010/04/22)
-
- Trans-stilbene as a starting material for the synthesis of tamoxifen based on palladium-catalyzed cross-coupling reactions
-
(Z)-Tamoxifen was synthesized from a simple olefin (trans-stilbene) in 5 steps and 40% overall yield (Z/E = 74:26). The phenyl substituted group (4-Me2NCH2CH2OC6H4) was attached by a bromination-dehydrobromination-Suzuki reaction sequence. Subsequently, the ethyl group was attached to the triarylated olefin by a bromination-Negishi reaction sequence. Both the Suzuki and Negishi cross-coupling processes are stereospecific, and the stereo-selectivity depends only on the bromination-dehydrobromination reactions. (Z)-Tamoxifen was also obtained from trans-stilbene in only 3 steps by using Heck reaction-bromination- Negishi reaction sequence in 57% overall yield (Z/E = 65:35). Georg Thieme Verlag Stuttgart.
- Nunes, Carolina M.,Limberger, Jones,Poersch, Silvia,Seferin, Marcus,Monteiro, Adriano L.
-
scheme or table
p. 2761 - 2765
(2010/01/21)
-
- Tetraalkylphosphonium trihalides. Room temperature ionic liquids as halogenation reagents
-
(Chemical Equation Presented) Six room temperature ionic liquids (RTILs) comprised of a tetraalkylphosphonium cation (tridecylmethyphosphonium or trihexyltetradecylphosphonium) and a trihalide anion (Br3 -, BrCl2-, or ClBr2-) have been prepared and characterized. Their ability to effect halogenation reactions with a variety of substrates has been explored. In general, halogenation reactions of alkenes proceed with high yields and stereo- and regioselectivities, whether performed in the absence or presence of a solvent (chloroform). Reactions of an alkyne and electrophilic substitution on an aromatic ring have been investigated as well. The facile preparation of the salts, their ease of handling, and the simplicity of product isolation should make these RTILs useful additions to the repertoire of halogenation reagents and the reagents of choice for specific transformations.
- Cristiano, Rodrigo,Ma, Kefeng,Pottanat, George,Weiss, Richard G.
-
supporting information; experimental part
p. 9027 - 9033
(2010/03/30)
-
- Facile one-pot synthesis of α-bromoketones from olefins using bromide/bromate couple as a nonhazardous brominating agent
-
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.
-
experimental part
p. 2529 - 2532
(2009/09/06)
-
- Comparative study of the vicinal functionalization of olefins with 2:1 bromide/bromate and iodide/iodate reagents
-
A comparative evaluation was made on the syntheses of vicinal halohydrins, halo methyl ethers, and halo acetates from olefins using 2:1 Br-/BrO3- and I-/IO3- reagents. In many cases both reagents afforded products selectively in high yields. The highest halogen atom efficiencies attained were 97% and 93% for Br-/BrO3- and I-/IO3-, respectively. Of the two reagents, I-/IO3- was established to be the preferred reagent for vicinal functionalization of linear alkenes and also for halo acetate preparation. However, only Br-/BrO3- was effective for vicinal functionalization of trans-stilbene and chalcones.
- Agrawal, Manoj K.,Adimurthy, Subbarayappa,Ganguly, Bishwajit,Ghosh, Pushpito K.
-
experimental part
p. 2791 - 2797
(2009/08/08)
-
- Bromination of alkenes and alkynes with (bromodimethyl)sulfonium bromide
-
Alkenes and alkynes were brominated efficiently in high yields with (bromodimethyl)sulfonium bromide in acetonitrile at room temperature. Alkenes produced the corresponding trans-dibromo compounds while alkynes (except phenylacetylene) afforded both the trans-dibromo products (major) and the tetrabromo derivatives (minor). However, phenylacetylene furnished solely the tetrabromo compound.
- Das, Biswanath,Srinivas, Yallamalla,Sudhakar, Chittaluri,Ravikanth, Bommena
-
experimental part
p. 188 - 190
(2009/07/18)
-
- Stereoselective bromination reactions using tridecylmethylphosphonium tribromide in a "stacked" reactor
-
(Chemical Equation Presented) A new reagent, tridecylmethylphosphonium tribromide, and new procedures for bromination reactions of unsaturated substrates (including one that allows several substrates to be reacted in sequence) are described. The procedures exploit the diffusion of components and the densities and immiscibilities of layers, including a fluorous "spacer" layer, within a reaction vessel. The stereoselectivities achieved in the reactions are superior in some cases to those found with other brominating reagents.
- Ma, Kefeng,Li, Shaw,Weiss, Richard G.
-
supporting information; experimental part
p. 4155 - 4158
(2009/06/06)
-
- The role of neat substrates in phase-vanishing and tandem phase-vanishing reactions
-
Phase-vanishing reactions are triphasic reactions, which involve a reagent, a liquid perfluoroalkane as a phase screen and a substrate. Aromatization, isomerization and halogenation of neat substrates under phase-vanishing conditions gave the expected products in good to excellent yields. In tandem single-phase-phase-vanishing reaction, two reactants, placed in the top phase, afforded the intermediate, which in a subsequent phase-vanishing reaction reacted with the reagent from the bottom phase to give the final product. The reaction worked well under solvent-free conditions on liquid substrates and intermediates. With solids, results were better if an additional solvent was employed.
- Windmon, Nicole,Dragojlovic, Veljko
-
scheme or table
p. 6543 - 6546
(2009/04/06)
-
- An efficient vanadium-catalyzed bromination reaction
-
An efficient catalytic oxidative bromination of arenes, alkenes, and alkynes in aqueous media was achieved under relatively mild conditions by using NH4VO3 catalyst combined with H2O2, HBr, and KBr. Dodecyltrimethylammonium bromide was found to serve as an efficient surfactant to facilitate the NH4VO3-catalyzed bromination in aqueous media.
- Moriuchi, Toshiyuki,Yamaguchi, Mitsuaki,Kikushima, Kotaro,Hirao, Toshikazu
-
p. 2667 - 2670
(2008/02/03)
-
- One-pot combination of the Wittig olefination with oxidation, hydrogenation, bromination, and photocyclization reactions
-
Co-polycondensation of tetramethoxysilane, 2-diphenyl(phosphino)ethyltri(ethoxy)silane, and N-2-(aminoethyl)-3-aminopropyltri(methoxy)silane forms a heterogenized tertiary phosphine reagent (HPR) that reacts with benzyl chlorides and aldehydes to give alkenes. This Wittig condensation can be coupled, as a one-pot process, with hydrogenation, oxidation, bromination or photocyclization.
- Hamza, Khalil,Blum, Jochanan
-
p. 293 - 295
(2007/10/03)
-
- Metal triflate catalyzed highly regio- and stereoselective 1,2-bromoazidation of alkenes using NBS and TMSN3 as the bromine and azide sources
-
Metal triflate catalyzed 1,2-bromoazidation of alkenes was performed using N-bromosuccinimide (NBS) and trimethylsilyl azide (TMSN3) as the bromine and azide sources, respectively. Among the metal triflates, Zn(OTf)2 was found to be the best catalyst. This catalytic process represents a highly regioselective, stereoselective and high yielding method for the synthesis of anti-1,2-bromoazides from a variety of alkenes including α,β-unsaturated carbonyl compounds.
- Hajra, Saumen,Sinha, Debarshi,Bhowmick, Manishabrata
-
p. 7017 - 7019
(2007/10/03)
-
- The important role of solvent vapor in an organic solid state reaction
-
Some organic reactions in the solid state proceeded very efficiently and selectively in the presence of a small amount of solvent vapor. The Royal Society of Chemistry 2005.
- Nakamatsu, Seiken,Toyota, Shinji,Jones, William,Toda, Fumio
-
p. 3808 - 3810
(2007/10/03)
-
- Rapid debromination of vic-dibromoalkanes with zinc powder in acetic acid under microwave irradiation
-
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
-
p. 282 - 284
(2007/10/03)
-
- Mild oxidative bromination of alkenes and alkynes with zinc bromide and lead tetraacetate
-
Zinc bromide and lead tetraacetate is a practical and safe source of bromine. The combined reagents are used to brominate a variety of alkenes to vicinal dibromoalkanes. Similarly, alkynes can be converted into dibromoalkenes in high yields. The reagents are also capable of tetrabromination of alkynes.
- Muathen, Hussni A.
-
p. 3545 - 3552
(2007/10/03)
-
- Selective conversion of epoxides to vic-halo alcohols and symmetrical or unsymmetrical dihalides by triphenylphosphine/2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ) in the presence of quaternary ammonium halides
-
A new method is described for the efficient and selective conversion of epoxides to vic-halo alcohols or symmetrical and unsymmetrical dihalides using PPh3/DDQ/R4NX (X = Cl, Br, I) as a mixed-reagent system.
- Iranpoor, Nasser,Firouzabadi, Habib,Aghapour, Ghasem,Nahid, Azarmidokht
-
p. 1885 - 1891
(2007/10/03)
-
- Structure-dependent oxidative bromination of unsaturated C-C bonds mediated by selectfluor
-
A number of olefins were subjected to oxidative bromination using Selectfluor/KBr. For different types of substrates, addition, monobromine-substituted, or Hunsdiecker-Borodin reaction products can be readily afforded.
- Ye, Chengfeng,Shreeve, Jean'Ne M.
-
p. 8561 - 8563
(2007/10/03)
-
- Solvolytic stereoselective debromination of vic-dibromides with HMPA
-
A simple and efficient procedure for the debromination of vic-dibromides has been reported with hexamethylphosphoric triamide at 155-160°C under a nitrogen atmosphere without the aid of any reagent.
- Khurana,Bansal,Chauhan
-
p. 1089 - 1091
(2007/10/03)
-
- Stereoselective halogenations of alkenes and alkynes in ionic liquids
-
(matrix presented) Room-temperature ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium chloride, are used as "green" recyclabl
- Chiappe, Cinzia,Capraro, Dario,Conte, Valeria,Pieraccini, Daniela
-
p. 1061 - 1063
(2007/10/03)
-
- A new method for stereoselective bromination of stilbene and chalcone in a water suspension medium
-
Bromination reactions of (E)-stilbene and (E)-chalcone in a water suspension medium proceeded efficiently and stereoselectively, and the reaction products were collected easily by filtration. The Royal Society of Chemistry 1999.
- Tanaka, Koichi,Shiraishi, Ryusukc,Toda, Fumio
-
p. 3069 - 3070
(2007/10/03)
-
- Carbon-halogen bond activation by Nickel catalyst: Synthesis of alkenes, from 1,2-dihalides
-
Unsaturated hydrocarbons can easily be prepared in a few seconds starting from 1,2 dibromides in the presence of a catalytic amount of Nickel diphenylphosphinoethane dichloride (NidppeCl2) and tri.n.butyl tin hydride, (TBTH) at room temperature. The dependencie of the nature of starting dihalides is investigated.
- Malanga, Corrado,Mannucci, Serena,Lardicci, Luciano
-
p. 1021 - 1028
(2007/10/03)
-
- Debrominations of vic-Dibromides with Diorganotellurides. 1. Stereoselectivity, Relative Rates, and Mechanistic Implications
-
Debrominations of vic-dibromides with diaryl tellurides 1-4 and di-n-hexyl telluride (9) are described. A mechanistic explanation of the debromination is offered which accounts for several key experimental observations: (1) the reaction is highly stereoselective with erythro-dibromides giving trans-olefins and threo-dibromides giving cis-olefins, (2) the reaction is accelerated by more electron-rich diorganotellurides, (3) the reaction is accelerated in a more polar solvent, (4) the reaction is accelerated by the addition of carbocation-stabilizing substituents to the carbons bearing the bromo substituents, and (5) erythro-dibromides are much more reactive than threo-dibromides. It is proposed that bromonium ion formation from the vic-dibromide is slow and rate-determining. Bromonium ion formation is followed by rapid scavenging of "Br-" by the diorganotelluride. The bromonium ion formation provides stereoselectivity and eclipsing interactions lower the reactivity of threo-dibromides. No intermediate species were observed by 1H NMR.
- Butcher, Timothy S.,Zhou, Feng,Detty, Michael R.
-
p. 169 - 176
(2007/10/03)
-
- Radical bromination of 1,1- and 1,2-diphenylethylenes in 1,2-dichloroethane
-
The radical bromination of 1,1- and 1,2-diphenylethylenes in 1,2-dichloroethane was investigated on the basis of kinetic and product distribution data. Whereas the ionic process followed a third-order rate law (second order in Br2), the radical
- Bellucci, Giuseppe,Chiappe, Cinzia
-
p. 685 - 692
(2007/10/03)
-
- Characterization of polycyclic aromatic hydrocarbon particulate and gaseous emissions from polystyrene combustion
-
The partitioning of polycyclic aromatic hydrocarbons (PAHs) between the particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres (100-300 μm) at different combustion temperatures (800- 1200 °C) to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments (differential mobility particle sizer and/or optical particle counter) to determine the particle size distribution. For chemical composition analyses, the particles were either collected on Teflon filters or split into eight size fractions using a cascade impactor with filter media substrates, while the gaseous products were collected on XAD-2 adsorbent. Gas chromatography/mass spectroscopy (GC/MS) was used to identify and quantify the specific PAH species, their partitioning between the gas and particulate phases, and their distribution as a function of emission particle size. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes. The experimental results have been analyzed to elucidate the formation mechanisms of PAHs and particles during polystyrene combustion. The implications of these results are also discussed with respect to the control of PAH emissions from municipal waste-to-energy incineration systems. The partitioning of polycyclic aromatic hydrocarbons (PAHs) between particulate and gaseous phases resulting from the combustion of polystyrene was studied. A vertical tubular flow furnace was used to incinerate polystyrene spheres to determine the effect of temperature and polystyrene feed size on the particulate and gaseous emissions and their chemical composition. The furnace reactor exhaust was sampled using real-time instruments to determine the particle size distribution. The total mass and number of PAH species in both the particulate and gas phases were found to decrease with increasing incineration temperature and decreasing polystyrene feed size, while the mean diameter of the particles increases with increasing incineration temperature and decreasing feed size. In addition, the PAH species in the particulate phase were found to be concentrated in the smaller aerosol sizes.
- Durlak, Susan K.,Biswas, Pratim,Shi, Jichun,Bernhard, Mary Jo
-
p. 2301 - 2307
(2007/10/03)
-
- Solid-state organic reactions proceeding by pulverization: Oxidation and halogenation with iodosobenzene and inorganic solid-supports
-
Pulverization-activation method was employed to accelerate solid-state organic reactions. Crushing and grinding of solid mixtures of hydrogen halide-treated silica gels, iodosobenzene and organic substrates in the absence of a solvent brought about smooth and rapid reactions to give halogenated and/or oxidized products in good yields. Various sulfides were smoothly converted to sulfonyl chlorides in one step in excellent yields. The surface of silica gel activated by pulverization serves as a reaction field on which reagent molecules can effectively encounter with each other.
- Sohmiya, Hajime,Kimura, Takahide,Fujita, Mitsue,Ando, Takashi
-
p. 13737 - 13750
(2007/10/03)
-