- Examination of subsequent reaction products enhanced through parahydrogen-induced nuclear polarization (PHIP)
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Homogeneous hydrogenation with parahydrogen yields strong nuclear spin polarization in the 1H NMR spectra of the reaction products. This polarization can be transferred to subsequent reaction products and detected by in situ 1H NMR s
- Koch, Andreas,Bargon, Joachim
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Read Online
- Green bromination method
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The invention discloses a green bromination method, and belongs to the field of green organic chemistry. Under the conditions of room temperature, opening and neutrality, reaction raw materials are aromatic hydrocarbon, olefin, alkyne, tryptamine, tryptophane and derivatives thereof with different functional groups, a bromine source is MBrx (M is Fe , Fe , Ce and the like, and x is 2-3), and the unique oxidant is H2O2. Brominated alkanes, alkenes, aromatic hydrocarbons, pyrrolo-indolines and furo-indolines and derivatives thereof can be produced. The bromination reaction is carried out by using easily available and cheap reagents (such as FeBr2, CeB3 and H2O2) in the market and the solvent, and the method has the characteristics of mild reaction conditions, wide substrate application range, simple steps, easiness in operation and no need of separation, is a green, environment-friendly and safe bromination reaction method, and has a good application prospect.
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Paragraph 0065-0067
(2021/06/13)
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- A General Method for the Dibromination of Vicinal sp3C-H Bonds Exploiting Weak Solvent-Substrate Noncovalent Interactions
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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
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supporting information
p. 2399 - 2404
(2021/03/03)
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- A Cascade Suzuki-Miyaura/Diels-Alder Protocol: Exploring the Bifunctional Utility of Vinyl Bpin
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Cascade reactions are an important strategy in reaction design, allowing streamlining of chemical synthesis. Here we report a cascade Suzuki-Miyaura/Diels-Alder reaction, employing vinyl Bpin as a bifunctional reagent in two distinct roles: as an organoboron nucleo phile for cross-coupling and as a Diels-Alder dienophile. Merging these two reactions enables a rapid and operationally simple synthesis of functionalized carbocycles in good yield. The effect of the organoboron subtype on Diels-Alder regioselectivity was investigated and postsynthetic modifications were carried out on a model substrate. The potential for a complementary Heck/Diels-Alder process was also assessed.
- Cain, David L.,McLaughlin, Calum,Molloy, John J.,Carpenter-Warren, Cameron,Anderson, Niall A.,Watson, Allan J. B.
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supporting information
p. 787 - 791
(2019/04/25)
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- Mild and Efficient Vicinal Dibromination of Olefins Mediated by Aqueous Ammonium Fluoride
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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
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supporting information
p. 419 - 424
(2018/02/23)
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- Photocatalytic Transfer Hydrogenolysis of Allylic Alcohols on Pd/TiO2: A Shortcut to (S)-(+)-Lavandulol
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We report herein a regio- and stereoselective photocatalytic hydrogenolysis of allylic alcohols to form unsaturated hydrocarbons employing a palladium(II)-loaded titanium oxide; the reaction proceeds at room temperature under light irradiation without stoichiometric generation of salt wastes. Olefin and saturated alcohol moieties tolerated the reaction conditions. Hydrogen atoms were selectively incorporated into less sterically congested carbons of the allylic functionalities. This protocol allowed a short-step synthesis of (S)-(+)-lavandulol from (R)-(?)-carvone by avoiding otherwise necessary protection/deprotection steps.
- Takada, Yuki,Caner, Joaquim,Kaliyamoorthy, Selvam,Naka, Hiroshi,Saito, Susumu
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supporting information
p. 18025 - 18032
(2017/12/08)
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- Electrochemical bromination of cyclic and acyclic enes using biphasic electrolysis
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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
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supporting information
p. 145 - 153
(2016/02/23)
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- On the bromination of aromatics, alkenes and alkynes using alkylammonium bromide: Towards the mimic of bromoperoxidases reactivity
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This article describes an efficient method of bromination of organic substrates including aromatics, alkenes and alkynes with NH4VO3as a catalyst and H2O2as an oxidant agent using a non-toxic and easy-to-handle source of bromine, tetrabutylammonium bromide. The process was developed under mild reaction conditions and is an innovation from reported methods in aspects such as: i) short reaction times, ii) the ability to work at room temperature, iii) regioselectivity and good yields.
- Mendoza, Fabian,Ruíz-Guerrero, Rosario,Hernández-Fuentes, Carlos,Molina, Paulina,Norzagaray-Campos, Mariano,Reguera, Edilso
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supporting information
p. 5644 - 5648
(2016/11/28)
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- Efficient bromination of olefins, alkynes, and ketones with dimethyl sulfoxide and hydrobromic acid
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The oxidative bromination of olefins, alkynes, and ketones has been developed with HBr as the brominating reagent and DMSO as the mild oxidant. The simple conditions, high bromide-atom-economy, as well as easy accessibility and low cost of DMSO and HBr make the present strategy prospective for the synthesis of dibrominated alkanes, dibrominated alkenes and α-bromoketones.
- Song, Song,Li, Xinwei,Sun, Xiang,Yuan, Yizhi,Jiao, Ning
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supporting information
p. 3285 - 3289
(2015/06/25)
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- Organocatalytic diastereoselective dibromination of alkenes
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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
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experimental part
p. 2708 - 2712
(2010/07/04)
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- The α-halogenation of α,β-unsaturated carbonyls and dihalogenation of alkenes using bisacetoxyiodobenzene/pyridine hydrohalides
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A procedure for the α-chlorination or bromination of a number of α,β-unsaturated carbonyls, and the dichlorination or bromination of alkenes, is developed using bisacetoxyiodobenzene (BAIB) and the HCl or HBr salt of pyridine. The reaction proceeds in an
- Ngatimin, Marsewi,Gartshore, Christopher J.,Kindler, Jeremy P.,Naidu, Sudha,Lupton, David W.
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scheme or table
p. 6008 - 6011
(2010/03/03)
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- An efficient vanadium-catalyzed bromination reaction
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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
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p. 2667 - 2670
(2008/02/03)
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- Substrate activation: Indirect β-bromination of alcohols
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The reversible oxidation of an alcohol into a ketone provides access to enol/enolate chemistry. Preliminary results have applied this principle to the β-bromination of alcohols.
- Cami-Kobeci, Gerta,Williams, Jonathan M.J.
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p. 124 - 126
(2007/10/03)
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- A Simple and Convenient Method for Epoxidation of Olefins without Metal Catalysts
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An easy method for epoxidation of olefins using bleach (sodium hypochlorite) and either a stoichiometric or catalytic amount of bromide ion has been developed. Without any transition metal catalyst a variety of non-activated olefins give epoxides in high yields and good selectivity at ambient conditions.
- Klawonn, Markus,Bhor, Santosh,Mehltretter, Gerald,Doebler, Christian,Fischer, Christine,Beller, Matthias
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p. 389 - 392
(2007/10/03)
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- An efficient bromination of alkenes using cerium(IV) ammonium nitrate (CAN) and potassium bromide
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Bromination of alkenes using a combination of potassium bromide and cerium(iv) ammonium nitrate (CAN) in a two phase system consisting of water and dichloromethane affords the corresponding dibromides in excellent yield. The reaction most likely involves the addition of the bromine radical generated from bromide ion by CAN and subsequent formation of the dibromide.
- Nair, Vijay,Panicker, Sreeletha B,Augustine, Anu,George, Tesmol G,Thomas, Siji,Vairamani
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p. 7417 - 7422
(2007/10/03)
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- Debrominations of vic-Dibromides with Diorganotellurides. 1. Stereoselectivity, Relative Rates, and Mechanistic Implications
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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.
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p. 169 - 176
(2007/10/03)
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- Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCI (HBr) Acetonitrile Reagent
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Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25-60 °C) with excellent to moderate yields.
- Liu, Lilian Kao,Lin, Ching-Shan
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- Synthesis of brominated compounds. A convenient molybdenum-catalyzed procedure inspired by the mode of action of haloperoxidases
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A two-phase (CHCl3/H2O) procedure for the synthesis of halogenated compounds has recently been developed. Such procedure mimics the mode of action of the enzymes haloperoxidases which contain vanadium in their active center. We have investigated the possibility to substitute vanadium with molybdenum. The molybdenum-based reactions show some advantages over the vanadium-based ones. In fact reaction times are shorter and overall yields are larger, under similar experimental conditions, both in the reaction with double bonds as well as with aromatic rings. Moreover, with double bonds, the molybdenum catalyzed process preferentially yields bromohydrins which are valuable synthetic intermediates. On the other hand, the molybdenum-catalyzed reactions show peculiar mechanistic features which deserve further investigation.
- Conte, Valeria,Di Furia, Fulvio,Moro, Stefano
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p. 8609 - 8612
(2007/10/03)
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- Vanadium Bromoperoxidases Mimicking Systems: Bromohydrins Formation as Evidence of the Occurance of a Hypobromite-Like Vanadium Complex.
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In the aqueous phase of a two-phase (H2O-CH2Cl2) system mimicking the hydrophilic and the hydrophobic portions of vanadium dependent bromoperoxidases, (V-BrPO), a mono peroxovanadium complex, formed in situ by addition of H2O2 to NH4VO3, oxidizes Br(-) to a species whose nature is still largely unknown.Such species displays a bromine-like reactivity toward organic substrates dissolved in CH2Cl2.The observation that styrene, 1-methyl- and 2-methyl styrenes afford, together with dibromo-compounds, appreciable amounts of bromohydrins, suggests that a hypobromite-like species also formed.Evidence is presented that such a species is a vanadium complex.
- Andersson, Malin,Conte, Valeria,Furia, Fulvio Di,Moro, Stefano
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p. 2675 - 2678
(2007/10/02)
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- The effect of polymer-supported reagent structure on bromination of organic molecules
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Crosslinked poly(styrene-co-4-vinylpyridine) reacted with hydrogen bromide or various alkyl bromides to pyridinium salts, which were further converted with chlorine to polymer supported reagents (1) containing up to 34% of chlorine, while substantial loss
- Zajc, Barbara,Zupan, Marko
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p. 6161 - 6166
(2007/10/02)
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- Selectivity Relationships and Substituent-Substituent Interactions in Carbocation-Forming Bromination. The Transition-State Contribution to the ρ Variation
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For arylolefin bromination through benzylic carbocations, X-C6H4-C+(R)-CHBr-R', there are 18 reaction constants, ρR, describing ring-substituent effect X, which vary from -1.6 to -5.9 depending on R and R' (H, Me, OMe, or Ar').This r
- Ruasse, Marie-Francoise,Argile, Alain,Dubois, Jacques-Emile
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p. 4846 - 4849
(2007/10/02)
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- A CONVENIENT SYNTHESIS OF α-BROMOKETONES FROM OLEFINS
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α-Bromoketones are prepared in good yields by the reaction of olefins with sodium bromite in aqueous acetic acid at room temperature.
- Kageyama, Toshifumi,Tobito, Yoshimichi,Katoh, Atsushi,Ueno, Yoshio,Okawara, Makoto
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p. 1481 - 1482
(2007/10/02)
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