- Electrogenerated Bases. 8. Epoxidations by Electrogenerated Superoxide with/without Auxiliary Carbon Acids. α,β-Unsaturated Ketones
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Excellent yields of the epoxides of cyclohexenone (14), 4,4-dimethylcyclohexenone (15), mesityl oxide (17), and benzalacetophenone (18) were obtained by treating the enones contained in the cathode chamber of an electrochemical cell with in situ electrogenerated superoxide in the presence of an auxiliary carbon acid such as diphenylacetonitrile (6) or, better, diethyl methylmalonate (1).Poor or no yields were obtained in the absence of the carbon acid.Products previously prepared by the rection of electrogenerated superoxide with these carbon acids alone were formed here as coproducts.A rationalization is offered for the effectiveness of this methodology and an explanation of the difference between these results and those that had been reported by others using potassium superoxide/18-crown-6 as an epoxidant.
- Sugawara, Michio,Baizer, Manuel M.
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- Olefins oxidation with molecular O2 in the presence of chiral Mn (III) salen complex supported on magnetic CoFe2O4@SiO2@CPTMS
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In the present study, CoFe2O4@SiO2@CPTMS nanocomposite was synthesized and the homogeneous chiral Mn-salen complex was anchored covalently onto the surface of CoFe2O4@SiO2@CPTMS nanocomposite. The heterogeneous Mn-salen magnetic nanocatalyst (CoFe2O4@SiO2@CPTMS@ chiral Mn (III) Complex) was characterized by different techniques including transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), powder X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Then, the aerobic enantioselective oxidation of olefins to the corresponding epoxide was investigated in the presence of magnetic chiral CoFe2O4@SiO2@Mn (III) complex at ambient conditions within 90?min. The results showed the corresponding products were synthesized with excellent yields and selectivity. In addition, the heterogeneous CoFe2O4@SiO2@ CPTMS@ chiral Mn (III) complex has benefits such as high selectivity and comparable catalytic reactivity with its homogeneous analog as well as mild reaction condition, facile recovery, and recycling of the heterogeneous catalyst.
- Hemmat, Kaveh,Nasseri, Mohammad A.,Allahresani, Ali
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- Synthesis of γ,δ-Unsaturated and δ,ε-Unsaturated α-Amino Acids from Fragmentation of γ- and δ-Lactones
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A noncoded amino acid of cyclomarin A (1) was synthesized in a racemic fashion. The method employs a six-membered ring template to control the relative stereochemistry and introduction of the functional groups. Ultimately, Pd-catalyzed fragmentation of the lactone provided γ-δ-unsaturated and δ,ε-unsaturated α-amino acids. A Pd-catalyzed ring opening of a γ-lactone is also reported.
- Tarver Jr., James E.,Joullie, Madeleine M.
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- Mesoporous SBA-15 materials modified with PW or W active species as catalysts for the epoxidation of olefins with H2O2
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Five catalysts containing PW or W active species that anchored onto aminosilylated mesoporous silica SBA-15 by a post-grafting route were prepared and the resulting PW or W/APTES/SBA-15 hybrid materials were characterized by XRD, N2 adsorption/desorption, surface area analysis, TEM, FT-IR, and ICP (inductively coupled plasma atomic emission spectroscopy). The names of these catalysts have been abbreviated as SBA-15m-a, SBA-15m-b, SBA-15m-c, SBA-15m-d, and SBA-15m-e according to the different active species. The PW or W active species were highly dispersed in the channels of the modified mesoporous materials. The interaction between PW or W species and amino groups grafted on the channel surface of SBA-15 led to the immobilization of PW or W species. Their catalytic activity in the epoxidation of cyclooctene with H 2O2 as oxidant was investigated. Among them, SBA-15m-a showed the best performance, with 98.9% conversion and 98.4% selectivity. The catalyst could be reused for six times with a little decrease in activity.
- Zhang, Aiping,Zhang, Yi,Wang, Puguang,Li, Jun,Lv, Ying,Gao, Shuang
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- Neighbouring effects on catalytic epoxidation by Fe-cyclam in M2-PDIxCy complexes
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The unsymmetric PDIeCy ligand, featuring pyridinediimine and cylam sites, can be selectively metalated. Complementing the diiron compound, we have synthesized two heterobimetallic isomers, [ZnPDIFeCy(PDIeCy)(OTf)4] (3) and [FePDIZnCy(PDIeCy)(OTf)4] (4), and a dizinc complex, [Zn2(PDIeCy)(OTf)4] (5). Olefin epoxidation by the series of complexes was investigated. The M-PDI site influences the reactivity of the M-cyclam, resulting in increased activity toward enones. This journal is
- Hofmann, Andreas J.,Niederegger, Lukas,Hess, Corinna R.
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supporting information
p. 17642 - 17648
(2020/12/30)
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- Metal-Free and Efficient Epoxidation of α,β-Unsaturated Ketones with 1,1,2,2-Tetrahydroperoxy-1,2-Diphenylethane as a Powerful Solid Oxidant
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1,1,2,2-Tetrahydroperoxy-1,2-diphenylethane was used for the efficient and metal-free epoxidation of various α,β-unsaturated ketones, carried out under mild alkaline conditions at room temperature.
- Khosravi, Kaveh,Naserifar, Shirin,Mahmoudi, Boshra
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p. 683 - 689
(2017/06/19)
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- Oxidation of olefins using molecular oxygen catalyzed by a part per million level of recyclable copper catalyst under mild conditions
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Copper catalysts with an imidazole salt tag ([Cu-Imace-R-H][X], X- = F-, Cl-, Br-, I-, CF3CO2-, HSO4-, NO3-, PF6- or BF4-; R = H or CH3) show quite high reactivity for the oxidation of non-aromatic olefins with good selectivity for epoxides. The reactions perform well with a part per million (ppm) catalyst loading at mild temperature and ambient pressure. The highest turnover frequency (TOF) reaches up to 900:000 h-1. The catalytic activity is easy to control by changing the anion of [Cu-Imace-R-H][X]. This catalyst is effective for a series of substrates, including internal and terminal olefins, tri- and tetra-substituted olefins and aromatic olefins. In addition, the copper catalyst can be conveniently separated from the reaction system and reused for at least six cycles without any obvious loss of catalytic activity.
- Yang, Guoqiang,Du, Huiyuan,Liu, Jia,Zhou, Zheng,Hu, Xingbang,Zhang, Zhibing
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p. 675 - 681
(2017/08/14)
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- Epoxidation of alkenes with aqueous hydrogen peroxide and quaternary ammonium bicarbonate catalysts
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A range of solid and liquid catalysts containing bicarbonate anions were synthesised and tested for the epoxidation of alkenes with aqueous hydrogen peroxide. The combination of bicarbonate anions and quaternary ammonium cations opens up for new catalytic systems that can help to overcome challenges with catalyst separation and reuse. Graphical Abstract: [Figure not available: see fulltext.]
- Mielby, Jerrik,Kegnaes, Soren
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p. 1162 - 1165
(2014/01/06)
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- The cinchona primary amine-catalyzed asymmetric epoxidation and hydroperoxidation of α,β-unsaturated carbonyl compounds with hydrogen peroxide
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Using cinchona alkaloid-derived primary amines as catalysts and aqueous hydrogen peroxide as the oxidant, we have developed highly enantioselective Weitz-Scheffer-type epoxidation and hydroperoxidation reactions of α,β-unsaturated carbonyl compounds (up to 99.5:0.5 er). In this article, we present our full studies on this family of reactions, employing acyclic enones, 5-15-membered cyclic enones, and α-branched enals as substrates. In addition to an expanded scope, synthetic applications of the products are presented. We also report detailed mechanistic investigations of the catalytic intermediates, structure-activity relationships of the cinchona amine catalyst, and rationalization of the absolute stereoselectivity by NMR spectroscopic studies and DFT calculations.
- Lifchits, Olga,Mahlau, Manuel,Reisinger, Corinna M.,Lee, Anna,Fares, Christophe,Polyak, Iakov,Gopakumar, Gopinadhanpillai,Thiel, Walter,List, Benjamin
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supporting information
p. 6677 - 6693
(2013/06/05)
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- Novel basic ionic liquid based on alkylammonium as efficient catalyst for Knoevenagel reaction
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The typical Knoevenagel condensation was carried out smoothly in the presence of a basic ionic liquid of N,N,N′,N′-tetramethyl-N′- hexyl-ethylenediammonium tetrafluoroborate ([TMHEDA]BF4), and 99% of yield was obtained using ethyl cyanoacetate and benzaldehyde as substrates at 60 °C for 1 h. Four reuses of the ionic liquid without dramatic decrease in catalytic activity for Knoevenagel condensation demonstrated the good stability and operability of the ionic liquid. Moreover, the typical nucleophilic addition reactions were also accomplished by the same ionic liquid to check its feasibility. The dual function of the basic ionic liquid both as solvent and catalyst, combined with simple product separation and recycling, is expected to contribute to the development of a green and environmentally friendly strategy. Copyright Taylor & Francis Group, LLC.
- Zhou, Shuai,Liu, Lu,Wang, Bo,Ma, Mingguo,Xu, Feng,Sun, Runcang
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experimental part
p. 1384 - 1391
(2012/04/10)
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- Amino-acid-mediated epoxidation of α,β-unsaturated ketones by hydrogen peroxide in aqueous media
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Amino acids, such as arginine and lysine, can be used as an efficient catalyst in the epoxidation of α,β-unsaturated ketones with aqueous hydrogen peroxide. Up to >99% conversion was obtained in the reaction toward 11 α,β-unsaturated ketones.
- Kim, Juhyun,Jung, Suhyun,Park, Seongsoon,Park, Sojung
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experimental part
p. 2866 - 2868
(2011/06/21)
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- Epoxidation of olefins with O2 and isobutyraldehyde catalyzed by cobalt (II)-containing zeolitic imidazolate framework material
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Co-containing zeolitic imidazolate framework material (Co-ZIF) was prepared and its catalytic performance in the aerobic epoxidation of olefins using isobutyraldehyde as reductant under mild conditions was first studied. Co-ZIF was characterized by XRD, FT-IR and X-ray single-crystal diffraction. It showed good performance in the epoxidation of olefins, with 100% conversion, 98.5% selectivity and 638.3 turnover frequency for the epoxidation of cyclooctene. Co-ZIF could be reused for 5 times without loss of its catalytic activity and the structure of the recovered catalyst was almost unchanged compared to that of the fresh one.
- Zhang, Aiping,Li, Linqing,Li, Jun,Zhang, Yi,Gao, Shuang
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experimental part
p. 1183 - 1187
(2012/05/20)
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- Epoxidation of electron-deficient αβ-unsatured carbonyl compounds over Keggin heteropoly compounds with acqueous H2O 2
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The epoxidation of a variety of electron-deficient α,β- unsaturated carbonyl compounds has been studied using a series of heteropoly compounds and aqueous hydrogen peroxide in acetonitrile. Among the heteropoly compounds investigated, (CTP)3VMo12O40 showed the highest catalytic performance for the epoxidation of these compounds.
- Gao, Qiang,Ding, Yong,Liu, Haitao,Suo, Jishuan
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p. 716 - 718
(2007/10/03)
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- Ultrasound-assisted epoxidation of olefins and α,β-unsaturated ketones over hydrotalcites using hydrogen peroxide
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An efficient ultrasound-assisted epoxidation of olefins and α,βunsaturated ketones over hydrotalcite catalysts in the presence of hydrogen peroxide and acetonitrile is described. This general and selective protocol is relatively fast and is applicable to a wide variety of substrates.
- Pillai, Unnikrishnan R.,Sahle-Demessie, Endalkachew,Varma, Rajender S.
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p. 2017 - 2027
(2007/10/03)
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- Microwave-expedited olefin epoxidation over hydrotalcites using hydrogen peroxide and acetonitrile
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An efficient microwave-assisted epoxidation of olefins is described over hydrotalcite catalysts in the presence of hydrogen peroxide and acetonitrile. This general and selective protocol is extremely fast and is applicable to a wide variety of substrates.
- Pillai, Unnikrishnan R,Sahle-Demessie, Endalkachew,Varma, Rajender S
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p. 2909 - 2911
(2007/10/03)
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- Epoxidation of α,β-Unsaturated Ketones Using Hydrogen Peroxide in the Presence of Basic Hydrotalcite Catalysts
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The basic layered hydrotalcites have been used as catalysts for the epoxidation of α,β-unsaturated ketones in heterogeneous reaction media using hydrogen peroxide as an oxidant. A wide variety of α,β-unsaturated ketones were oxidized to the corresponding epoxyketones in excellent yields under mild reaction conditions. For example, 2-cyclohexen-1-one gave 2,3-epoxycyclohexanone in 91% yield at 40°C for 5 h with high efficiency in hydrogen peroxide. The catalytic activity of the hydrotalcites increased as the basicity of their surfaces increased. In the case of the epoxidation of less reactive substrates, adding a cationic surfactant such as n-dodecyltrimethylammonium bromide (DTMAB) to the above oxidation system accelerated the epoxidation reaction. These hydrotalcite catalysts were easily separated from the reaction mixture and were reusable.
- Yamaguchi, Kazuya,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 6897 - 6903
(2007/10/03)
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- Inverse phase transfer catalysis. III.- Optimization of the epoxidation reaction of α,β-unsaturated ketones by hydrogen peroxide
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The epoxidation of chalcone using hydrogen peroxide in the presence of a base in a two-phase medium system following the so-called Inverse Phase Transfer Catalysis (IPTC) process was investigated. Careful examination of various parameters including surfactant concentration, pH, H2O2 decomposition side-reactions and epoxide ring-opening, allowed us to determine optimal experimental conditions.
- Boyer, Bernard,Hambardzoumian, Araik,Roque, Jean-Pierre,Beylerian, Norair
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p. 6147 - 6152
(2007/10/03)
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- Highly chemo- and regioselective rearrangement of α,β-epoxy ketones to 1,3-dicarbonyl compounds in 5 mol dm-3 lithium perchlorate-diethyl ether medium
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Epoxides from α,β-unsaturated ketones undergo highly chemo- and regioselective rearrangement to 1,3-dicarbonyl compounds in 5 mol dm-3 lithium perchlorate-diethyl ether medium by a 1,2-migration of the carbonyl group at ambient conditions. The Royal Society of Chemistry 1999.
- Sankararaman,Ncsakumar
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p. 3173 - 3175
(2007/10/03)
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- Microwave Promoted Epoxidation of α,β-Unsaturated Ketones in Aqueous Sodium Perborate
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A series of α,β-unsaturated ketones has been treated with sodium perborate in water and 1,4-dioxane under microwave irradiation to produce α,β-epoxyketones in good yields.
- Sharifi, Ali,Bolourtchian, Mohammad,Mohsenzadeh, Farshid
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p. 668 - 669
(2007/10/03)
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- Oxygen transfer reactions from an oxaziridinium tetrafluoroborate salt to olefins
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Oxaziridinium 5 efficiently epoxidises olefins. It reacts as an electrophilic reagent and does not transfer its oxygen to deactivated double-bonds or carbonyl functions. Epoxidation of cyclic allylic acetates shows a remarkable diastereoselectivity leading to the syn isomer. We propose that the epoxidation reaction proceeds through a one-step process.
- Lusinchi, Xavier,Hanquet, Gilles
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p. 13727 - 13738
(2007/10/03)
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- Hydrotalcite-Promoted Epoxidation of Electron-Deficient Alkenes with Hydrogen Peroxide
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A synthetic anionic clay, hydrotalcite (Mg/Al=2.8), promotes the epoxidation of electrondeficient alkenes with H2O2.With open-chain, α,β-unsaturated carbonyl compounds 3-hydroxy-1,2-dioxolanes are also obtained.
- Cativiela, Carlos,Figueras, Francois,Fraile, Jose M.,Garcia, Jose I.,Mayoral, Jose A.
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p. 4125 - 4128
(2007/10/02)
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- Epoxidation of α,β-unsaturated ketones with sodium perborate
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α,β-Unsaturated ketones are rapidly converted to epoxyketones at room temperature in aqueous sodium perborate in the presence of a phase transfer catalyst. Organic solvents can be used to modify the rate of epoxidation.
- Straub, Thomas S.
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p. 663 - 664
(2007/10/02)
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- Chromium Silicalite-2 (CrS-2): an Efficient Catalyst for the Chemoselective Epoxidation of Alkenes with TBHP
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Chromium-containing medium-pore molecular sieve (Si/Cr > 140) having MEL (CrS-2) topology efficiently catalyses the chemoselective epoxidation of various olefins to the corresponding epoxides using 70percent tert-butyl hydroperoxide (TBHP) as an oxidant.
- Joseph, Reni,Sasidharan, M.,Kumar, R.,Sudalai, A.,Ravindranathan, T.
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p. 1341 - 1342
(2007/10/02)
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- The reaction of trialkylstannylmethyllithium with α,β-epoxy ketones and α-chloro ketones
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The reactions of trialkylstannylmethyllithium with α,β-epoxy ketones afforded mainly cyclopropanols, while α-chloro ketones afforded allyl alcohols and/or cyclopropanols, in varying amounts depending upon the molar ratio of the reagent to the substrate.
- Sato, Tadashi,Kikuchi, Toshihiro,Tsujita, Hiroshi,Kaetsu, Atsushi,Sootome, Norio,Nishida, Ken-Ichiro,Tachibana, Kazutaka,Murayama, Eigoro
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p. 3281 - 3304
(2007/10/02)
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- THE OXIDATION OF α-β-UNSATURATED KETONES IN AQUEOUS SODIUM PERBORATE
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A series of α-β-unsaturated ketones has been prepared with sodium perborate in water and a cosolvent to produce the corresponding epoxides in good yield.The reaction constitutes a mild and convenient method for the synthesis of α-β-epoxyketones.
- Reed, Kathryn L.,Gupton, John T.,Solarz, Traci L.
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p. 3579 - 3588
(2007/10/02)
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- Trisubstituted (Stannylmethyl)lithium as a Methylene Double Anion Equivalent. Reaction with Esters
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Trisubstituted (stannylmethyl)lithium reacts with electrophiles as a methylene double anion equivalent to produce enolates from esters.The reaction mechanism is discussed.
- Sato, Tadashi,Matsuoka, Hiroharu,Igarashi, Tsutomu,Minomura, Masafumi,Murayama, Eigoro
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p. 1207 - 1212
(2007/10/02)
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- SODIUM PERBORATE OXIDATIONS OF CYCLIC AND ACYCLIC ALKENES TO OXIRANES OR VICINAL ACETOXY ALCOHOLS
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Under different reaction conditions, sodium perborate/acetic anhydride oxidizes alkenes into oxiranes or vicinal acetoxy alcohols in good yields.
- Xie, Gaoyang,Xu, Linxiao,Hu, Jun,Ma, Shiming,Hou, Wei,Tao, Fenggang
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p. 2967 - 2968
(2007/10/02)
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- Competitive Reactions of Diene Cation Radicals Formed on Irradiated Metal Oxide Surfaces
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The heterogeneous photochemical oxygenation of conjugated dienes induced by long wavelength UV irradiation of TiO2 powders suspended in oxygenated CH3CN was studied.In nearly all cases, products resulting from the oxidative cleavage of the double bonds were observed, in parallel to that previously reported for monoolefins.A mechanism is proposed which involves the intermediacy of a diene cation radical generated by transfer of an electron from the adsorbed diene to a photogenerated hole localized at the surface of the excited TiO2 particle.Non-oxidative cleavage products are also observed, and the effect of the semiconductor surface in controlling reactivity of the photogenerated cation radical is discussed.The first examples of aromatization and Diels-Alder dimerization mediated by irradiated semiconductor suspensions are presented.
- Fox, Marye Anne,Sackett, Debra D.,Younathan, Janet N.
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p. 1643 - 1660
(2007/10/02)
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- THE REACTION OF α-STANNYLMETHYLLITHIUM WITH ESTERS
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Ketonic compounds were prepared from esters using α-stannylmethyllithium as the reagent.
- Sato, Tadashi,Matsuoka, Hiroharu,Igarashi, Tsutomu,Murayama, Eigoro
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p. 4339 - 4342
(2007/10/02)
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- EPOXIDATION WITH 30percent HYDROGEN PEROXIDE CATALYZED BY TUNGSTIC ACID IN BUFFERED MEDIA
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The scope of the tungstic acid catalyzed hydrogen peroxide epoxidation of olefinic alcohols is examined at room temperature, in buffered protic media.Epoxidation occurs with complete retention of configuration for both cis and trans alkenes.Chemoselectivity is discussed with respect to the olefinic alcohol structure and olefin substituents.
- Prat, Denis,Lett, Robert
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p. 707 - 710
(2007/10/02)
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- CHEMICAL TRANSFORMATIONS OF QINGHAOSU, A PEROXIDIC ANTIMALARIAL
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This paper discusses the stereochemistry of 2 and 10, two previously reported transformation products of qinghaosu (1).The structures of two products, 3 and 9, are also presented.
- Zeng, Mei-Yi,Li, Lan-Na,Chen, Shu-Feng,Li, Guang-Yi,Liang, Xiao-Tian,et al.
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p. 2941 - 2946
(2007/10/02)
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- Kinetics of Epoxidation of α,β-Unsaturated Ketones in Methanol Medium
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The kinetics of epoxidation of α,β-unsaturated ketones by alkaline H2O2 in methanol in the temperature range 25-40 deg C has been studied.The addition follows second order kinetics.The results indicate that the concentration of NaOH has a significant effect on the reactivity.The effect of various substituents in these reactions show that electron-releasing groups attached to the β-carbon atom in the olefin diminish the rate and electron-attracting groups enhance it.The oxidative cleavage of a few substituted epoxychalkones by hydroperoxide anion has also been studied in methanol at 30 deg C.Adherence to second order kinetics is excellent in every case and the rates are slower than those of the corresponding chalkones.The stability of epoxides depends on the substituents; electron-releasing groups diminish the rate and electron-attracting groups enhance it as observed in the case of epoxidation.The reaction obeys the Arrhenius equation and the respective activation parameters have been calculated.The effect of solvent polarity on the rate of epoxidation has been studied.The differences in the rates in methanol and water as solvents have been explained on the basis of solvent-solute interaction.
- Rama Rao, D. Sri
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p. 786 - 789
(2007/10/02)
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- SYNTHESIS OF 2-ALKYLTHIO-5-ACETYL-2-OXAZOLINES
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The reaction of 2-acetyloxiranes with alkyl thiocyanates in the presence of Lewis acids (BF3, AlCl3) has given 2-alkylthio-5-acetyl-2-oxazolines (yields 40-60percent).It has been shown that the reaction of trans-2-acetyl-3-methyloxirane and of trans-2-acetyl-3-methyloxirane and of trans-2-acetyl-2,3-dimethyloxirane with alkyl thiocyanates takes place stereospecifically and leads to cis-2-alkylthio-5-acetyl-2-oxazolines.
- Bubel', O.N.,Tishchenko, I.G.,Grinkevich, O.A.,Abramov, A.F.
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p. 352 - 355
(2007/10/02)
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