- Synthesis of Benzoisoselenazolone Derivatives by Nickel-Catalyzed Dehydrogenative Direct Selenation of C(sp2)-H Bonds with Elemental Selenium in Air
-
Nickel-catalyzed direct selenation of benzamides bearing an 8-quinolyl auxiliary with elemental selenium provides benzoisoselenazolones in good yield via carbon-selenium and nitrogen-selenium bond formation under aerobic conditions. In addition to aryl C-
- Iwasaki, Masayuki,Miki, Natsumi,Tsuchiya, Yuta,Nakajima, Kiyohiko,Nishihara, Yasushi
-
-
Read Online
- Bromolactonization of alkenoic acids mediated by V2O5via bromide to bromenium in situ oxidation
-
An efficient protocol for the bromolactonization of alkenoic acids is presented that obviates the use of molecular bromine or exogenous bromenium sources. Vanadium (V) oxide catalyzes the in situ oxidation of bromide salts to bromenium (Br+) in
- Campbell, McKenzie L.,Rackley, Samuel A.,Giambalvo, Lauren N.,Whitehead, Daniel C.
-
-
Read Online
- Bromoiodinanes with an I(III)-Br bond: Preparation, X-ray crystallography and reactivity as electrophilic brominating agents
-
Bromoiodinanes - conveniently and directly prepared from iodobenzenecarbinols and N-bromosuccinimide, and characterised for the first time crystallographically - act as electrophilic bromine donors. The Royal Society of Chemistry 2006.
- Braddock, D. Christopher,Cansell, Gemma,Hermitage, Stephen A.,White, Andrew J. P.
-
-
Read Online
- H2O2 Production at Low Overpotentials for Electroenzymatic Halogenation Reactions
-
Various enzymes utilize hydrogen peroxide as an oxidant. Such “peroxizymes” are potentially very attractive catalysts for a broad range of oxidation reactions. Most peroxizymes, however, are inactivated by an excess of H2O2. The electrochemical reduction of oxygen can be used as an in situ generation method for hydrogen peroxide to drive the peroxizymes at high operational stabilities. Using conventional electrode materials, however, also necessitates significant overpotentials, thereby reducing the energy efficiency of these systems. This study concerns a method to coat a gas-diffusion electrode with oxidized carbon nanotubes (oCNTs), thereby greatly reducing the overpotential needed to perform an electroenzymatic halogenation reaction. In comparison to the unmodified electrode, with the oCNTs-modified electrode the overpotential can be reduced by approximately 100 mV at comparable product formation rates.
- Bormann, Sebastian,van Schie, Morten M. C. H.,De Almeida, Tiago Pedroso,Zhang, Wuyuan,St?ckl, Markus,Ulber, Roland,Hollmann, Frank,Holtmann, Dirk
-
-
Read Online
- Amidines as potent nucleophilic organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes
-
(±)-iso-Amarine is a potent organocatalyst at 1 mol % loading for both the bromoacetoxylation of alkenes with added acetic acid and bromolactonisation of unsaturated carboxylic acids with stoichiometric NBS as the electrophilic bromine source. A simple br
- Ahmad, Simon M.,Braddock, D. Christopher,Cansell, Gemma,Hermitage, Stephen A.,Redmond, Joanna M.,White, Andrew J.P.
-
-
Read Online
- Oxidative oxygen-nucleophilic bromo-cyclization of alkenyl carbonyl compounds without organic wastes using alkali metal reagents in green solvent
-
A bromo-lactonization of alkenyl carboxylic acids and a bromo-cyclization of N-allyl amides as oxygen-nucleophilic bromo-cyclization reactions were developed via the oxidative umpolung of bromide using alkali metal bromide and inorganic oxidant to provide
- Moriyama, Katsuhiko,Nishinohara, Chihiro,Sugiue, Toru,Togo, Hideo
-
-
Read Online
- Fenton chemistry for Achmatowicz rearrangement
-
Achmatowicz rearrangement (AchR) is a very important transformation for the synthesis of various heterocyclic building blocks and natural products. Here, the discovery of Fenton chemistry for AchR using a bifunctional catalyst (FeBr2 or CeBrsu
- Zhao, Guodong,Liang, Lixin,Wang, Eryu,Tong, Rongbiao
-
-
Read Online
- Chalcogen-Bonding Catalysis with Telluronium Cations
-
Chalcogen bonding results from non-covalent interactions occurring between electrodeficient chalcogen atoms and Lewis bases. Among the chalcogens, tellurium is the strongest Lewis acid, but Te-based compounds are scarcely used as organocatalysts. For the first time, telluronium cations demonstrated impressive catalytic properties at low loadings in three benchmark reactions: the Friedel–Crafts bromination of anisole, the bromolactonization of ω-unsaturated carboxylic acids and the aza-Diels–Alder between Danishefsky's diene and imines. The ability of telluronium cations to interact with a Lewis base through chalcogen bonding was demonstrated on the basis of multi-nuclear (17O, 31P, and 125Te) NMR analysis and DFT calculations.
- Aubert, Emmanuel,Mamane, Victor,Pale, Patrick,Weiss, Robin
-
supporting information
p. 19281 - 19286
(2021/07/25)
-
- Electrochemical bromofunctionalization of alkenes in a flow reactor
-
The bromination of organic molecules has been extensively studied to date, yet there is still a demand for safe and sustainable methodologies. Hazardous reagents, selectivity, low atom economy and waste production are the most persisting problems of brominating reagents. The electrochemical oxidation of bromide to bromine is a viable strategy to reduce waste by avoiding chemical oxidants. Furthermore, thein situgeneration of reactive intermediates minimizes the risk of hazardous reagents. In this work, we investigate the electrochemical generation of bromine from hydrobromic acid in a flow electrochemical reactor. Various alkenes could be converted to their corresponding dibromides, bromohydrines, bromohydrin ethers and cyclized products in good to excellent yields.
- Seitz, Jakob,Wirth, Thomas
-
supporting information
p. 6892 - 6896
(2021/08/20)
-
- Cooperativity within the catalyst: alkoxyamide as a catalyst for bromocyclization and bromination of (hetero)aromatics
-
Alkoxyamide has been reported as a catalyst for the activation ofN-bromosuccinimide to perform bromocyclization and bromination of a wide range of substrates in a lipophilic solvent, where adequate suppression of the background reactions was observed. The key feature of the active site is the alkoxy group attached to the sulfonamide moiety, which facilitates the acceptance as well as the delivery of bromonium species from the bromine source to the substrates.
- Mondal, Haripriyo,Sk, Md Raja,Maji, Modhu Sudan
-
supporting information
p. 11501 - 11504
(2020/10/12)
-
- New syntheses of haloketo acid methyl esters and their transformation to halolactones by reductive cyclization
-
A new method for haloketo acid methyl ester synthesis on the basis of the ring-opening of cyclic α,β-unsaturated ketones followed by halogenation under mild conditions is reported. Di- and tri-haloketo acid methyl esters are conveniently synthesized via the hydrolytic ring-opening reaction through this method. Halolactones were readily obtained from these haloketo acid methyl esters by reductive cyclization employing NaBH4 and trifluoroacetic acid. Derivatizations of the obtained halolactone utilizing the exo-halomethylene moiety were also demonstrated.
- China, H.,Dohi, T.,Fujitake, M.,Kageyama, N.,Kikushima, K.,Yatabe, H.
-
p. 1804 - 1810
(2020/10/16)
-
- Chemoenzymatic Halocyclization of γ,δ-Unsaturated Carboxylic Acids and Alcohols
-
A chemoenzymatic method for the halocyclization of unsaturated alcohols and acids by using the robust V-dependent chloroperoxidase from Curvularia inaequalis (CiVCPO) as catalyst has been developed for the in situ generation of hypohalites. A broad range of halolactones and cyclic haloethers are formed with excellent performance of the biocatalyst.
- Younes, Sabry H. H.,Tieves, Florian,Lan, Dongming,Wang, Yonghua,Süss, Philipp,Brundiek, Henrike,Wever, Ron,Hollmann, Frank
-
-
- Formate Oxidase (FOx) from Aspergillus oryzae: One Catalyst Enables Diverse H2O2-Dependent Biocatalytic Oxidation Reactions
-
An increasing number of biocatalytic oxidation reactions rely on H2O2 as a clean oxidant. The poor robustness of most enzymes towards H2O2, however, necessitates more efficient systems for in situ H2O2 generation. In analogy to the well-known formate dehydrogenase to promote NADH-dependent reactions, we here propose employing formate oxidase (FOx) to promote H2O2-dependent enzymatic oxidation reactions. Even under non-optimised conditions, high turnover numbers for coupled FOx/peroxygenase catalysis were achieved.
- Tieves, Florian,Willot, Sébastien Jean-Paul,van Schie, Morten Martinus Cornelis Harald,Rauch, Marine Charlène Renée,Younes, Sabry Hamdy Hamed,Zhang, Wuyuan,Dong, JiaJia,Gomez de Santos, Patricia,Robbins, John Mick,Bommarius, Bettina,Alcalde, Miguel,Bommarius, Andreas Sebastian,Hollmann, Frank
-
supporting information
p. 7873 - 7877
(2019/05/10)
-
- Applications of Selenonium Cations as Lewis Acids in Organocatalytic Reactions
-
The use of trisubstituted selenonium salts as organic Lewis acids in electrophilic halogenation and aldol-type reactions has been developed. The substrate scope is broad. The reaction conditions are mild and compatible with various functionalities. This study opens a new avenue for the development of nonmetallic Lewis acid catalysis.
- He, Xinxin,Wang, Xinyan,Tse, Ying-Lung (Steve),Ke, Zhihai,Yeung, Ying-Yeung
-
supporting information
p. 12869 - 12873
(2018/09/14)
-
- (HMe 2 SiCH 2) 2: A Useful Reagent for B(C 6 F 5) 3 -Catalyzed Reduction-Lactonization of Keto Acids: Concise Syntheses of (-)- cis -Whisky and (-)- cis -Cognac Lactones
-
(HMe 2 SiCH 2) 2 has been utilized as a useful reagent for B(C 6 F 5) 3 -catalyzed reduction-lactonization of keto acids to synthesize γ- and δ-lactones. The process led concisely to (-)- cis -whisky and (-)- cis -cognac lactones in respective overall yields of 32% and 36%.
- Xie, Hengmu,Lu, Ji,Gui, Yingying,Gao, Lu,Song, Zhenlei
-
supporting information
p. 2453 - 2459
(2017/10/06)
-
- Organoselenium and DMAP co-catalysis: Regioselective synthesis of medium-sized halolactones and bromooxepanes from unactivated alkenes
-
A catalytic system consisting of bis(4-methoxyphenyl)selenide and 4-(dimethylamino)pyridine (DMAP) has been developed for the regioselective synthesis of medium-sized bromo/iodo lactones and bromooxepanes possessing high transannular strain. 77Se NMR, mass spectrometry and theoretical studies reveal that the reaction proceeds via a quaternary selenium intermediate.
- Verma, Ajay,Jana, Sadhan,Prasad, Ch. Durga,Yadav, Abhimanyu,Kumar, Sangit
-
supporting information
p. 4179 - 4182
(2016/03/19)
-
- Indole-Catalyzed Bromolactonization in Lipophilic Solvent: A Solid-Liquid Phase Transfer Approach
-
We have developed a novel indole-catalyzed bromolactonization of olefinic acids. The reaction could be conducted in lipophilic solvent through a solid-liquid phase transfer mechanism. This catalytic protocol has been applied to the synthesis of base-sensitive bromolactones. (Chemical Equation Presented).
- Chen, Tao,Foo, Thomas Jian Yao,Yeung, Ying-Yeung
-
p. 4751 - 4755
(2015/08/18)
-
- Vanadium (V) oxide mediated bromolactonization of alkenoic acids
-
A full account of our recently communicated method for the V2O5 mediated bromolactonization of alkenoic acids is presented. Here we describe the extensive evaluation of the metal oxide catalyst, terminal oxidant, halide source, solvent system, and reaction temperature that resulted in optimal conditions employing 0.05 equiv V2O5, 3 equiv urea-hydrogen peroxide complex (UHP), and 3 equiv of NH4Br in an acetone:H2O (6:1) solvent system at room temperature. Additionally, we have expanded the substrate scope of the reaction with the aim of evaluating the functional group tolerance of the transformation. Further, we present preliminary data of a related halogenation of β-diketones with our optimal conditions. Finally, we probed the role of urea in the transformation.
- Campbell, McKenzie L.,Rackley, Samuel A.,Giambalvo, Lauren N.,Whitehead, Daniel C.
-
p. 3895 - 3902
(2015/06/02)
-
- Xerogel-sequestered silanated organochalcogenide catalysts for bromination with hydrogen peroxide and sodium bromide
-
While H2O22 is a powerful oxidant, decomposing into environmentally benign H2O and O2, a catalyst is often required for reactions with H2O2 to proceed at synthetically useful rates. Organotellurium and organoselenium compounds catalyze the oxidation of ha
- Gatley, Caitlyn M.,Muller, Lisa M.,Lang, Meredith A.,Alberto, Eduardo E.,Detty, Michael R.
-
p. 9616 - 9639
(2015/08/06)
-
- Sulfoxide-mediated Umpolung of alkali halide salts
-
A new protocol for the direct two-electron oxidative Umpolung of alkali halide salts is reported. This procedure, relying on the use of a commercially available sulfoxide as the oxidant, allows the electrophilic halogenation of carbonyl compounds as well as halolactonisation reactions to proceed from the corresponding sodium salts, at room temperature and under mild conditions.
- Klimczyk, Sebastian,Huang, Xueliang,Fares, Christophe,Maulide, Nuno
-
supporting information; experimental part
p. 4327 - 4329
(2012/06/29)
-
- Isoselenazolones as catalysts for the activation of bromine: Bromolactonization of alkenoic acids and oxidation of alcohols
-
Isoselenazolones were synthesized by a copper-catalyzed Se-N bond forming reaction between 2-halobenzamides and selenium powder. The catalytic activity of the various isoselenazolones was studied in the bromolactonization of pent-4-enoic acid. Isoselenazolone 9 was studied as a catalyst in several reactions: the bromolactonization of a series of alkenoic acids with bromine or N-bromosuccinimide (NBS) in the presence of potassium carbonate as base, the bromoesterification of a series of alkenes using NBS and a variety of carboxylic acids, and the oxidation of secondary alcohols to ketones using bromine as an oxidizing reagent. Mechanistic details of the isoselenazolone-catalyzed bromination reaction were revealed by 77Se NMR spectroscopic and ES-MS studies. The oxidative addition of bromine to the isoselenazolone gives the isoselenazolone(IV) dibromide, which could be responsible for the activation of bromine under the reaction conditions. Steric effects from an N-phenylethyl group on the amide of the isoselenazolone and electron-withdrawing fluoro substituents on the benzo fused-ring of the isoselenazolone appear to enhance the stability of the isoselenazolone as a catalyst for the bromination reaction.
- Balkrishna, Shah Jaimin,Prasad, Ch Durga,Panini, Piyush,Chopra, Deepak,Kumar, Sangit,Detty, Michael R.
-
p. 9541 - 9552,12
(2012/12/12)
-
- Efficient medium ring size bromolactonization using a sulfur-based zwitterionic organocatalyst
-
Catalytic bromolactonization of long-chain olefinic acids resulting in the efficient synthesis of medium-sized lactones is reported using a zwitterionic catalyst and stoichiometric N-bromosuccinimide halogen source. The reaction was found to be more efficient at 0 °C than at room temperature, which could be attributed to the temperature dependence of the zwitterionic catalyst.
- Cheng, Yi An,Chen, Tao,Tan, Chong Kiat,Heng, Jun Jie,Yeung, Ying-Yeung
-
supporting information
p. 16492 - 16495,4
(2020/09/15)
-
- Imidazolium-containing diselenides for catalytic oxidations with hydrogen peroxide and sodium bromide in aqueous solutions
-
The design and synthesis of imidazolium-containing diselenides 4a-c is described. The introduction of the N-methylimidazolium group gives freely soluble compounds in water, unlike the majority of common organic diselenides. Catalytic amounts of 4a-c effectively promote bromination of organic substrates using a safe and inexpensive NaBr/H2O2 system in water. Kinetics experiments revealed that the bromination of 4-pentenoic acid has a first-order dependence with respect to both NaBr and H2O2 concentrations The rate of reaction was also sensitive to the pH of the solution. Preparative reactions showed that, compared to 4a, diphenyl diselenide 5 was a poor catalyst and the ionic liquid 1-benzyl-3-methylimidazolium bromide 6 showed no catalytic activity with H2O2 indicating synergy from the combined functionality.
- Alberto, Eduardo E.,Detty, Michael R.,Braga, Antonio L.
-
p. 10476 - 10481,6
(2012/12/12)
-
- Novel catalytic bromolactonization of alkenoic acids using iodobenzene and Oxone
-
The novel catalytic reaction for bromolactonization of alkenoic acids is reported. When iodobenzene is used as recyclable catalyst in combination with Oxone as terminal oxidant, the cyclization of various 4-pentenoic acids with sodium bromide is easily carried out in CF3CH2OH at room temperature and giving five-membered bromolactones in good yields.
- He, Yan,Pu, Ye,Shao, Bo,Yan, Jie
-
experimental part
p. 695 - 698
(2011/07/30)
-
- Molecular sieves as an efficient and recyclable catalyst for bromolactonization and bromoacetoxylation reactions
-
Bromolactonization of unsaturated acids and bromoacetoxylation of olefins proceeded smoothly in the presence of molecular sieves and N-bromosuccinimide. The molecular sieves can be recycled and reused, and the halogen carrier can be recovered effectively.
- Chen, Feng,Jiang, Xiaojian,Er, Jun Cheng,Yeung, Ying-Yeung
-
experimental part
p. 3433 - 3435
(2010/09/07)
-
- Study on the bromolactonisation of alkenoic acids with (diacetoxyiodo) benzene
-
A study on the bromolactonisation of alkenoic acids is reported. When various pent-4-enoic acids reacted with (diacetoxyiodo)benzene (DIB) and lithium bromide in CH3OH at room temperature, most of the five-membered bromolactones were obtained in good to excellent yields in short times. Some had two diastereoisomers. When but-3-enoic acid and trans-hex-3-enoic acid were treated under the same conditions, only unsaturated lactones were found after workup. When hex-5-enoic acid was subjected to the same conditions, however, the desired six-membered bromolactone was not successfully separated.
- He, Yan,Yang, Zhenping,Yan, Jie
-
experimental part
p. 167 - 169
(2010/07/08)
-
- Asymmetric bromolactonization using amino-thiocarbamate catalyst
-
A novel amino-thiocarbamate-catalyzed bromolactonization of unsaturated carboxylic acids has been developed. The scope of the reaction is evidenced by 22 examples of γ-lactones with up to 99% yield and 93% ee. The protocol was applied in the enantioselective synthesis of the key intermediates of VLA-4 antagonists.
- Zhou, Ling,Tan, Chong Kiat,Jiang, Xiaojian,Chen, Feng,Yeung, Ying-Yeung
-
scheme or table
p. 15474 - 15476
(2011/02/21)
-
- Phase-vanishing reactions with ptfe (teflon) as a phase screen
-
Phase-vanishing reactions are triphasic reactions, which involve a reagent, a liquid perfluoroalkane, and a substrate. In a phase-vanishing reaction with PTFE tape as the phase screen instead of a liquid perfluoroalkane, there is no limitation related to the density of a phase and the denser phase can be in the top layer. The reactions were faster compared to traditional PV reactions, and it was possible to carry out sequential and tandem reactions and reactions under a reflux.
- Van Zee, Nathan J.,Dragojlovic, Veljko
-
supporting information; experimental part
p. 3190 - 3193
(2009/11/30)
-
- 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)
-
- A xerogel-sequestered selenoxide catalyst for brominations with hydrogen peroxide and sodium bromide in an aqueous environment
-
(Chemical Equation Presented) 4-(Hydroxymethyl)phenyl benzyl selenoxide (4) sequestered in a halide-permeable, Class II xerogel formed from 10/90 (mol/mol) 3-aminopropyltriethoxysilane/tetraethoxysilane catalyzes the bromination of organic substrates (4-pentenoic acid, 3,5-dihydroxybenzoic acid, 1,3,5-trimethoxybenzene, N-phenylmorpholine, and N,N-dimethylaniline) with NaBr and H2O2. Catalyst performance (reaction rate) when sequestered within the halide-permeable xerogel is 23-fold greater in comparison to xerogel-free catalyst in solution. The catalyst is easily separated from the reaction mixture via filtration and the recovered catalyst can be reused without loss of activity through formation of the first 80 mol of product per mole of catalyst.
- Bennett, Stephanie M.,Tang, Ying,McMaster, Danielle,Bright, Frank V.,Detty, Michael R.
-
p. 6849 - 6852
(2008/12/22)
-
- Synthesis of (±)-4-alkanolides from pent-4-enoic acid
-
Synthesis of (±)-4-hexanolide, (±)-4-nonanolide, and (±)-4-dodecanolide, racemic forms of the insect signal substances, has been accomplished by cationic cyclization of pent-4-enoic acid and its amide in the key step.
- Ugurchieva,Lozanova,Zlokazov,Veselovsky
-
experimental part
p. 657 - 659
(2009/05/16)
-
- Dimethylformamide, dimethylacetamide and tetramethylguanidine as nucleophilic organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes
-
Dimethylformamide, dimethylacetamide and tetramethylguanidine were found to act as increasingly active catalysts for the bromolactonisation of γ,δ- and δ,ε-unsaturated carboxylic acids with N-bromosuccinimide. The catalysts are readily removed in the work
- Ahmad, Simon M.,Braddock, D. Christopher,Cansell, Gemma,Hermitage, Stephen A.
-
p. 915 - 918
(2008/02/04)
-
- An approach to enantioselective 5-endo halo-lactonization reactions
-
Enantioselective lactonization of 4-substituted but-3-enoic acids using iodobis(N-methylephedrine) hexafluoroantimonate in dichloromethane at low temperatures is reported. The presence of bis(N-methylephedrine)silver(I) hexafluoroantimonate, derived from
- Garnier, Jean Marc,Robin, Sylvie,Rousseau, Gerard
-
p. 3281 - 3291
(2008/02/10)
-
- Selenium-catalyzed oxidative halogenation
-
Organoselenides catalyze the oxidation of halides by H2O2. Furthermore, these selenides catalyze the transfer of oxidized halogens from N-halosuccinimides to olefins and ketones. Thus, organoselenides catalyze oxidative halogenation reactions including halolactonization, α-halogenation of ketones, and allylic halogenation. The ability of selenium to undergo reversible 2e- oxidation-reduction chemistry facilitates halogenation through selenium-bound halogen intermediates.
- Mellegaard-Waetzig, Shelli R.,Wang, Chao,Tunge, Jon A.
-
p. 7191 - 7198
(2007/10/03)
-
- Ortho-substituted iodobenzenes as novel organocatalysts for bromination of alkenes
-
Suitably ortho-substituted iodobenzenes act as organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes via the intermediacy of bromoiodinanes. The Royal Society of Chemistry 2006.
- Braddock, D. Christopher,Cansell, Gemma,Hermitage, Stephen A.
-
p. 2483 - 2485
(2008/03/28)
-
- An efficient chemoenzymatic approach to (S)-γ-fluoroleucine ethyl ester
-
(Chemical Equation Presented) An asymmetric synthesis of (S)-γ-fluoroleucine ethyl ester 1 is described. The key transformation involves a lipase-catalyzed dynamic ring-opening of 2-(3-butenyl)azlactone 7b with EtOH to give amide ester (S)-6b in 84% enant
- Limanto, John,Shafiee, Ali,Devine, Paul N.,Upadhyay, Veena,Desmond, Richard A.,Foster, Bruce R.,Gauthier Jr., Donald R.,Reamer, Robert A.,Volante
-
p. 2372 - 2375
(2007/10/03)
-
- (Diacetoxyiodo)benzene-Lithium Bromide as a Convenient Electrophilic Br+ Source
-
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.
-
p. 461 - 464
(2007/10/03)
-
- Selenium-catalyzed halolactonization: Nucleophilic activation of electrophilic halogenating reagents
-
Diphenyl diselenide catalyzes the halolactonization of unsaturated acids with N-halosuccinimides under mild conditions. The diselenide not only accelerates the reactions, but in some cases affords regiocontrol in favor of γ-lactone products. Experiments s
- Mellegaard, Shelli R.,Tunge, Jon A.
-
p. 8979 - 8981
(2007/10/03)
-
- A direct method for the conversion of terminal epoxides into γ-butanolides
-
A new and efficient process for the conversion of terminal epoxides to γ-butanolides is described involving Lewis acid promoted epoxide ring-opening by 1-morpholino-2-trimethylsilyl acetylene. Addition of a terminal epoxide to a solution of the ynamine an
- Movassaghi, Mohammad,Jacobsen, Eric N.
-
p. 2456 - 2457
(2007/10/03)
-
- Iodination of organic substrates with halide salts and H2O2 using an organotelluride catalyst.
-
[figure: see text] Organotelluride 1 is a water-soluble catalyst for the oxidation of iodide with hydrogen peroxide in pH 6 phosphate buffer. In two-phase systems, organic substrates are efficiently iodinated using 0.8 mol % of catalyst. Water-soluble substrates are iodinated without an organic cosolvent.
- Higgs,Nelen,Detty
-
p. 349 - 352
(2007/10/03)
-
- Br+ and I+ transfer from the halonium ions of adamantylideneadamantane to acceptor olefins. Halocyclization of 1,ω-alkenols and alkenoic acids proceeds via reversibly formed intermediates
-
The kinetics of the transfer of X+ from the bromonium and iodonium ions of adamantylideneadamantane (1-Br+ and 1-I+) to some 1,ω-alkenols and alkenoic acids in ClCH2CH2Cl at 25°C was investigated. In all cases, the expected products of halocyclization were observed. For the iodonium ion transfer the reaction kinetics are second order overall, first order in both 1-I+ and acceptor olefin. Transfer of the bromonium ion from 1-Br+ to these acceptor olefins exhibits different kinetic characteristics. In most cases, the rate of the Br+ transfer is subject to strong retardation in the presence of added parent olefin (Ad=Ad), suggestive of a common species rate depression. In some cases, such as 4-penten-1-ol (2b) and 4-pentenoic acid (4b), the reaction can be completely suppressed at high [Ad=Ad]. In other cases, such as 3-buten-1-ol (2a), 5-hexen-1-ol (2c), cyclohexene, 4-(hydroxymethyl)cyclohexene (3), and 5-endo-carboxynorbornene (5), added Ad=Ad does not suppress the reaction completely. In the cases of the 1,ω-alkenols, the reactions appear to exhibit kinetic terms that are greater than first order in alkenol. In these cases, alcohols such as 1-pentanol also accelerate the reaction, pointing to the involvement of the hydroxyl group of the second alkenol as a catalytic species. A unifying mechanism consistent with the data that involves two reversibly formed intermediates is presented.
- Neverov,Brown
-
p. 962 - 968
(2007/10/03)
-
- New Method for Preparation of 2,4-Disubstituted 4-Bromomethylbutanolides
-
A method is proposed for preparation of 2,4-didubstituted 4-bromomethylbutanolides via oxidative bromination of 2,4-disubstituted 4-hexenoic acids with a mixture of hydrobromic acid and hydrogen peroxide.The method is simple in operation, it involves accessble starting compounds and gives the target products in high yields.
- Arutyunyan, V. S.,Kochikyan, T. V.,Egiazaryan, N. S.,Avetisyan, A. A.
-
-
- Dimethyl Sulfoxide-Trimethylsilyl Bromide-Amine System as a Bromonium Ion Source Containing a Potential Internal Nucleophile; Unusual Bromolactonization of Cyclohex-3-enecarboxylic Acid Derivatives
-
Bromo lactones have been successfully obtained from unsaturated carboxylic acids by employing a dimethyl sulfoxide-trimethylsilyl bromide-amine system.The characteristic feature of this system is that unusual cis-addition and cyclisation of the sterically
- Miyashita, Kazuyuki,Tanaka, Akira,Mizuno, Hiroaki,Tanaka, Masahiro,Iwata, Chuzo
-
p. 847 - 852
(2007/10/02)
-
- NOVEL BROMOLACTONIZATION USING A DIMETHYL SULFOXIDE-TRIMETHYLSILYL BROMIDE-AMINE SYSTEM; UNUSUAL CIS-ADDITION OF TRANS-6-SUBSTITUTED 3-CYCLOHEXENE-1-CARBOXYLIC ACIDS
-
A novel method for bromolactonization using a dimethyl sulfoxide-trimethylsilyl bromide-amine system and the first example for halolactonization in the mode of cis-addition are described.
- Iwata, Chuzo,Tanaka, Akira,Mizuno, Hiroaki,Miyashita, Kazuyuki
-
p. 987 - 991
(2007/10/02)
-
- A Convenient Method for Bromolactonization
-
Bromolactones are conveniently obtained from unsaturated acids, bromine, and thallium(I) carbonate.
- Cambie, Richard C.,Rutledge, Peter S.,Somerville, Robyn F.,Woodgate, Paul D.
-
p. 1009 - 1011
(2007/10/02)
-