- OXIDATION OF ALCOHOLS WITH OXOPEROXOBIS-(N-PHENYLBENZOHYDROXAMATO)MOLYBDENUM(VI)
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The title complex oxidizes primary and secondary alcohols to the corresponding carbonyl compounds.Stereoselective epoxidation of allylic alcohols is also described.
- Tomioka, Hiroki,Takai, Kazuhiko,Oshima, Koichiro,Nozaki, Hitosi,Toriumi, Koshiro
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- Zeolite-Catalyzed Epoxidation Of Allylic Alcohols
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4 Angstroem molecular sieves have shown to be efficient catalysts for regio- and stereoselctive epoxidation of allylic alcohols.
- Antonioletti, R.,Bonadies, F.,Locati, L.,Scettri, A.
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- Regio-, diastereo-, and chemoselectivities in the dioxirane oxidation of acyclic and cyclic allylic alcohols by methyl(trifluoromethyl)dioxirane (TFD): A comparison with dimethyldioxirane
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The solvent-dependent shift in the regioselectivity of the geraniol epoxidation by methyl(trifluoromethyl)dioxirane (TFD) reveals that as for the less reactive dimethyldioxirane (DMD). hydrogen bonding stabilizes the transition state of the epoxidation. In protic media, the hydrogen bonding is exerted intermolecularly by the solvent, whereas in unpolar, non-hydrogen-bonding solvents intramolecular assistance through the adjacent hydroxy functionality comes into the play and the attack on the allylic alcohol moiety is favored. For chiral allylic alcohols, additional steric interactions control the π-facial selectivity in the conformationally fixed transition state. Analogous to DMD, the preferred dihedral angle in the hydrogen-bonded transition state of the TFD epoxidation constitutes approximately 130°, but contrary to DMD and for synthetic purposes important, the allylic alcohols and derivatives 1 and 3-5 investigated here are chemoselectively epoxidized by TFD without formation of the corresponding enones.
- Adam, Waldemar,Paredes, Rodrigo,Smerz, Alexander K.,Veloza, L. Angela
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- Catalytic epoxidation activity of keplerate polyoxomolybdate nanoball toward aqueous suspension of olefins under mild aerobic conditions
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Catalytic efficiency of a sphere-shaped nanosized polyoxomolybdate {Mo 132} in the aerobic epoxidation of olefins in water at ambient temperature and pressure in the absence of reducing agent is exploited which resulted good-to-high yields and desired selectivity.
- Rezaeifard, Abdolreza,Haddad, Reza,Jafarpour, Maasoumeh,Hakimi, Mohammad
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- Hydroxyselenation of Allylic Alcohols
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Hydroxyselenation of terminal or cyclic allylic alcohols occurs with high regio- and stereoselectivity to give β,β'-dihydroxyphenylselenated adducts in high yields.A mechanism for this selectivity is proposed.The utility of these adducts is illustrated by the conversion of the hydroxyselenide (9a) to the epoxide (11) via the intermediacy of a selenone.
- Cooper, Matthew A.,Ward, A. David
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- Synthesis and structural characterization of molybdenum(VI) and iron(II) coordination compounds with S-alkyl-N-methyl-S-(2-pyridyl)sulfoximines and catalytic epoxidation activity of the molybdenum complexes
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Coordination compounds oxido(diperoxido)(S-butyl-N-methyl-S-(2-pyridyl) sulfoximine)molybdenum(VI), [MoO(O2)2{SO(NMe) nBu(NC5H4)}] (5c), and bis{(dichlorido)(N,S- dimethyl-2-pyridylsulfoximine)iron(II)}, tetrahydrofuran solvate (1:1) (6), [FeCl2{SO(NMe)Me(NC5H4)}]2· THF are prepared from the free ligand 4 and molybdenum(VI) oxidediperoxide(dihydrate) and iron dichloride, respectively. The crystal structures reveal a trigonal bipyramid with the pyridine ring and the single oxygen on molybdenum in a trans arrangement for 5c and a planar μ2-Cl2Fe2 ring with trans-oriented exocyclic Cl atoms for 6 whereas the structures of the N,N-dicoordinated ligands are only little effected by the metals. Coordination compounds (5) efficiently catalyze the epoxidation of cyclooctene or of monosubstituted alkenes by tert-butyl hydroperoxide.
- Brussaard, Yvonne,Olbrich, Falk,Schaumann, Ernst
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- A SUPPORTED EPOXIDATION CATALYST FOR NUCLEOPHILIC OLEFINS
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A polystyrene-supported peptid-linked epoxidation catalyst is described and its utility for the discovery of new epoxidants is discussed.
- Okamoto, Yasushi,Still, W. Clark
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- Effect of Transition Metal Compounds on the Cyclohexene Oxidation Catalyzed by N-Hydroxyphthalimide
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Abstract: N-Hydroxyphthalimide (NHPI) is an efficient organic catalyst in the oxidation reactions of organic compounds occurring via a radical mechanism, often used together with redox-active ions or transition metal complexes. In this work the catalytic action of NHPI is studied together with Cu(II), Fe(III), and Mo(VI) compounds in the reaction of aerobic oxidation of cyclohexene in an acetonitrile solution at 60°C. It was found that iron(III) benzoate accelerates the reaction by rapidly generating the active form of the phthalimide-N-oxyl radical (PINO) catalyst, but does not cause decomposition of the hydroperoxide. The oxidation product is 2-cyclohexenyl hydroperoxide formed with a selectivity of 85% at a cyclohexene conversion of 50%. Copper(II) acetate initiates oxidation and is capable of catalyzing the radical decomposition of the hydroperoxide and secondary oxidation of allyl oxygenates. When reaching a cyclohexene conversion close to 80%, the overall selectivity to the main products, 2-cyclohexenyl hydroperoxide and 2-cyclohexen-1-on, was 70%. The addition of iron(III) and molybdenum(VI) compounds led to the intensive generation of hydroperoxide and its activation as an electrophilic reactant capable of cyclohexene epoxidation. As a result of the use of the multifunctional three-component NHPI–Mo(VI)–Fe(III) catalyst, cyclohexene oxidation by molecular oxygen occurred with the formation of epoxycyclohexane. The selectivity to the products of cyclohexene epoxidation was close to 50%, which is a value expected from theory.
- Kuznetsova,Kuznetsova,Yakovina,Zudin,Bal’zhinimaev
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- An investigation into oxo analogues of molybdenum olefin metathesis complexes as epoxidation catalysts for alkenes
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The oxo-imido molybdenum complex 2a is an effective catalyst at low catalyst loadings (0.5 mol % or below) for the epoxidation of a range of alkenes with tBuOOH in PhMe at 90 °C. Reactions are complete in less than 4 h and the products are isolated in high yields. The catalytic system is chemoselective for the epoxidation of electron-rich alkenes and allylic alcohols.
- Anderson, James C.,Smith, Neil M.,Robertson, Michelle,Scott, Mark S.
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- The mechanism of oxidation of allylic alcohols to α,β-unsaturated ketones by cytochrome P450 a
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The oxidation of cyclohex-2-en-1-ol, a simple model substrate for allylic alcohols, is catalyzed by several P450 isoenzymes and leads exclusively to cyclohex-2-en-1-one. No double bond epoxidation or C(4) hydroxylation have been observed. The large primary kinetic isotope effect measured using [2H]-1-cyclohex-2-en-1-ol is consistent with an at least partially rate limiting breaking of the C(1)-H bond. The mass spectrometric analysis of cyclohex-2-en-1-one obtained from [18O]cyclohex-2-en-1-ol has established that a gem-diol intermediate is involved, even if a dual hydrogen abstraction pathway may contribute to the reaction.
- Bellucci, Giuseppe,Chiappe, Cinzia,Pucci, Laura,Gervasi, Pier Giovanni
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- Catalytic efficacy of an oxido-peroxido tungsten(VI) complex: Synthesis, X-ray structure and oxidation of sulfides and olefins
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An oxido-peroxido tungsten(VI) complex [WO(O2)L(CH 30H)] using salicylidene benzoyl hydrazine as a tridentate ONO donor Schiff base (H2L) has been synthesized and characterized by elemental analysis, IR, 1H NMR, molar conductance data, and single-crystal X-ray analysis. The complex was used as a catalyst for epoxidation of olefins and oxidation of sulfides. The results show that epoxides and sulfoxides were produced in high yield, turnover number, and selectivity.
- Amini, Mojtaba,Bagherzadeh, Mojtaba,Eftekhari-Sis, Bagher,Ellern, Arkady,Woo, L. Keith
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- Solvent-free epoxidation using a tungstic acid catalyst on fluoroapatite
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Tungstic acid dispersed on fluoroapatite solid phase (H2WO4/FAp) catalyzed the epoxidation of cycloalkenes and allylic alcohols with a solid urea-hydrogen peroxide complex (urea-H2O2) without a solvent.
- Ichihara, Junko
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- Diastereoselective epoxidation of cyclohexene derivatives by dioxiranes generated in situ. Importance of steric and field effects
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In this paper, diastereoselective epoxidation of substituted cyclohexenes (substrates 1-7) by dioxiranes generated in situ from ketones and Oxone was systematically investigated. The results revealed that the diastereoselectivity was determined by the steric and field effects of both dioxiranes and substrates, and high diastereoselectivity can be achieved by tuning the ketone structure. Among the ketones tested, 12 and 19 gave the best diastereoselectivities.
- Yang, Dan,Jiao, Guan-Sheng,Yip, Yiu-Chung,Wong, Man-Kin
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- Hydrogen bond donor functionalized dioxido-molybdenum(VI) complexes as robust and highly efficient precatalysts for alkene epoxidation
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The synthesis of four novel, tridentate aminophenolate ligands HL1-HL4, bearing amide functionalities is reported. Reaction of these ligands with a dioxido molybdenum(VI) precursor led, depending on the choice of solvent, to mononuclear complexes of the type [MoO2L(OMe)] (2, 4, 6) or dinuclear complexes [{MoO2L}2(μ-O)] (1, 3, 5, 7), containing one facially, tridentate ONO-ligand per metal center. This synthetic discrimination between dinuclear and mononuclear complexes allows for a comparison between structures and reactivity. Complexes 1-7 were found to be highly active catalysts in the epoxidation of several internal and terminal alkenes. With tert-butyl hydroperoxide (TBHP) as oxidant, precatalyst loadings of 0.0005 mol% (5 ppm) could be realized leading to turnover numbers of up to 110000. The precatalysts also allowed for the use of hydrogen peroxide (0.1 mol% precatalyst) as oxidant as well as various alcohols as “green” solvents, such as ethanol or even tert-butanol (usually an inhibitor of epoxidation).
- Zwettler, Niklas,Schachner, J?rg A.,Belaj, Ferdinand,M?sch-Zanetti, Nadia C.
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- Stereoselective Synthesis of cis,cis-Configured Perhydroquinoxaline-5-Carbonitrile from Cyclohex-2-en-1-ol
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cis,cis-Configured perhydroquinoxaline-5-carbonitrile 10 was synthesized stereoselectively by ditosylation of trans,cis-2,3-dihydroxycyclohexane-1-carbonitrile 4 and subsequent reaction with ethylenediamine. The diol precursor 4 was stereoselectively obtained by regioselective opening of the epoxide 3 with KCN in water avoiding hazardous Et2AlCN.
- Schulte, Adrian,Saito, Susumu,Wünsch, Bernhard
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- Kinetic resolution of epoxy alcohols with the Sharpless Ti-isopropoxide/tartaric ester complex
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When investigating the Sharpless epoxidation of enol-protected 4-hydroxy-1,2-cyclopentanediones, the ability of the asymmetric Ti(OiPr)4/tartaric ester complex to discriminate between enantiomeric epoxides formed in situ was discovered, leading to the epoxide opening reaction of only one enantiomer. This observation was used in the kinetic resolution of racemic substituted 2,3-epoxy-4-hydroxy-cyclopentanol, to afford enantiomerically enriched epoxyalcohols in good yields and with ees up to 96%.
- Maljutenko, Karolin,Paju, Anne,J?rving, Ivar,Pehk, T?nis,Lopp, Margus
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- Catalytic performance of Keplerate polyoxomolybdates in green epoxidation of alkenes with hydrogen peroxide
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In this work, the catalytic perspective of three Keplerate polyoxometalates, Mo72M30 (M = V, Cr, Fe) in the epoxidation of various alkenes is considered. The catalytic reactions were performed in water under mild conditions and high to excellent conversions and selectivities were obtained using H2O2 as oxidant and Mo72Cr30 as the best catalyst. Keplerate POM catalysts have shown a very good recyclability, up to five times, without any appreciable decreases in catalytic activity and selectivity.
- Jalilian, Fariba,Yadollahi, Bahram,Riahi Farsani, Mostafa,Tangestaninejad, Shahram,Amiri Rudbari, Hadi,Habibi, Rouhollah
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- Olefin Epoxidation with α-Hydroperoxides of Esters, Amides, Ketones, and Nitriles
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A number of α-substituted hydroperoxides are capable of olefin epoxidation; unusual cis-trans selectivities are observed in reactions with olefins substituted with phenyl-groups.
- Rebek, Julius,McCready, Russell,Wolak, Raymond
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- Stereoselective Reduction of α,β-Epoxy Ketones into erythro-α,β-Epoxy Alcohols with Sodium Borohydride in the Presence of Calcium Chloride
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erythro-α,β-Epoxy alcohols were prepared with high steroselectivity by sodium borohydride reduction of the corresponding α,β-epoxy ketones in the presence of calcium chloride or manganese(II) chloride regardless of the substituents on the epoxide ring.
- Fujii, Hideaki,Oshima, Koichiro,Utimoto, Kiitiro
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- Catalytic Epoxidation of Alkenes with Oxone
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A practical, general and efficient protocol for the catalytic epoxidation of alkenes has been developed.The in situ generation of reactive dioxiranes capable of epoxidizing a variety of alkenes under biphasic conditions has been accomplished using phase transfer catalysts bearing a carbonyl group.Optimal epoxidation conditions employ 10 mol percent of 1-dodecyl-1-methyl-4-oxopiperidinium triflate (8d(+)OTf(-)) in a CH2Cl2/pH 7.5-8.0 biphase using potassium monoperoxosulfate (Oxone) as the oxidant.Optimization of the conditions identified (1) slow addition rate, (2) pH 7.5-8.0, (3) N-dodecyl chain, and (4) the triflate salt as key experimental and structural variables.A selection of nine olefins was successfully oxidized to the corresponding epoxides in 83-96percent yield.
- Denmark, Scott E.,Forbes, David C.,Hays, David S.,DePue, Jeffrey S.,Wilde, Richard G.
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- Stereoselective epoxidation with dioxiranes generated from ketones
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Dioxiranes generated in situ from potassium monoperoxysulfate and cyclohexanones stereoselectively oxidized cyclohexene derivatives to afford epoxides.
- Kurihara, Masaaki,Ito, Sachiko,Tsutsumi, Nozomi,Miyata, Naoki
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- Catalytic Epoxidation of Olefins with t-Butyl Hydroperoxide in the Presence of Polymer-supported Vanadium(V) an Molybdenum(VI) Complexes
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Oxovanadium(V) and oxomolybdenum(VI) ions have been incorporated into cross-linked polystyrene resins functionalized with iminodiacetic acid or diethylenetriamine derivatives.The polymer complexes have been used as catalysts in the epoxidation of olefins with t-butyl hydroperoxide.Vanadium(V) complexes promote epoxidation of allylic alcohols in a highly regioselective manner, e.g., 2,3-epoxide has been preferentially obtained in 98percent selectivity from (E)-geraniol at 80 deg C.The catalytic activity of the vanadium(V) complexes is generally higher than that of the molybdenum(VI) complexes in the epoxidation of allylic alcohols whereas an opposed trend holds for the epoxidation of cyclohexene.Life time of catalysts have been examined by repeated use of the complexes in the epoxidation of (E)-geraniol at 80 degC in benzene.Approximately 15-25percent of vanadium has been leaked out of the polymer beads on five time recycles leading to the decrease in the yield of 2,3-epoxide from initial value of 98percent to 95-93percent.Neither appreciable loss of metal nor reduction of catalytic activity has been observed in the molybdenum complex systems over five runs.
- Yokoyama, Toshiro,Nishizawa, Masato,Kimura, Tetsuo,Suzuki, Toshishige M.
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- Heterogeneous epoxidation of alkenes with H2O2 catalyzed by a recyclable organic-inorganic polyoxometalate-based framework catalyst
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Four organic-inorganic polyoxometalate-based frameworks (HSiW-MOF, PMo-MOF, HPMo-MOF and PW-MOF) were synthesised and characterized by elemental analysis, UV-vis and FT-IR spectroscopy, cyclic voltammetry and XRD analysis. Organic-inorganic polyoxometalate-based frameworks could act as effective and reusable heterogeneous catalysts for selective epoxidation of alkenes with aqueous hydrogen peroxide in acetonitrile. In the presence of PW-MOF, various kinds of alkenes could selectively be converted into the corresponding epoxides with high conversion and selectivity. PW-MOF was stable to leaching, behaved as true heterogeneous catalysts, easily recovered by filtration, and reused four times with maintenance of the catalytic performance.
- Haddadi, Hedayat,Hafshejani, Shahrbanou Moradpour,Farsani, Mostafa Riahi,Babahydari, Ali Kazemi
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- Chemo- and stereoselective reduction of α,β-epoxyketones with diisopropoxytitanium(III) tetrahydroborate
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Reduction of α,β-epoxyketones with diisopropoxytitanium(III) tetrahydroborate in dichloromethane under mild conditions (-78°→20°C) provides anti- (or erythro-) α,β-epoxy alcohols in high yields with high degree of chemo- and stereoselectivity.
- Ravikumar,Chandrasekaran, Srinivasan
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- Cobalt complex in a room temperature ionic liquid: A convenient recyclable reagent for catalytic epoxidation of cyclic alkenes
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Co-catalyzed epoxidation of cyclic alkenes proceeds in ionic liquid media (1-ethyl-3-methylimidazolium hexafluorophosphate). Epoxidation of the alkenes to respective epoxides was greatly accelerated by the use of a cobalt-based catalyst in the presence of H2O2 as an oxidant. The catalyst in ionic liquid [Emim]PF6 was recycled and reused for about seven times.
- Ramakrishna, Dileep,Ramachandra Bhat, Badekai,Hanumanthappa, Suresha Kumara T.
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- Photocatalytic oxidation of cyclohexene on titanium(IV)oxide
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Photocatalytic oxidation of cyclohexene was carried out over a series of titanium(IV) oxide catalysts. These species acting together with molecular oxygen significantly differed in their surface and structural properties. Attention was paid to elimination of the total decomposition of the alkene molecules to water and carbon dioxide and to favour formation of reaction intermediates, comprising epoxide units. Experiments were performed in liquid phase at atmospheric pressure, room temperature and under UV illumination. A quartz reactor was used and the reaction mixture was agitated by oxygen. Significant variations in the reaction selectivity were detected as a function of catalyst structural properties.
- Klisakova, Jana,Kluson, Petr,Cerveny, Libor
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- g-C3N4/metal halide perovskite composites as photocatalysts for singlet oxygen generation processes for the preparation of various oxidized synthons
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g-C3N4/metal halide perovskite composites were prepared and used for the first time as photocatalysts forin situ1O2generation to perform hetero Diels-Alder, ene and oxidation reactions with suitable dienes and alkenes. The standardized methodology was made applicable to a variety of olefinic substrates. The scope of the method is finely illustrated and the reactions afforded desymmetrized hydroxy-ketone derivatives, unsaturated ketones and epoxides. Some limitations were also observed, especially in the case of the alkene oxidations, and poor chemoselectivity was somewhere observed in this work which is the first application of MHP-based composites forin situ1O2generation. The experimental protocol can be used as a platform to further expand the knowledge and applicability of MHPs to organic reactions, since perovskites offer a rich variety of tuning strategies which may be explored to improve reaction yields and selectivities.
- Corti, Marco,Chiara, Rossella,Romani, Lidia,Mannucci, Barbara,Malavasi, Lorenzo,Quadrelli, Paolo
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p. 2292 - 2298
(2021/04/12)
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- Highly selective and efficient olefin epoxidation with pure inorganic-ligand supported iron catalysts
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Over the past two decades, there have been major developments in the transition iron-catalyzed selective oxidation of alkenes to epoxides; a common structure found in drug, isolated natural products, and fine chemicals. Many of these approaches have enabled highly efficient and selective epoxidation of alkenes via the design of specialized ligands, which facilitates to control the activity and selectivity of the reactions catalyzed by iron atom. Herein, we report the development of the olefin epoxidation with inorganic-ligand supported iron-catalysts using 30% H2O2 as an oxidant, and the mechanism is similar to iron-porphyrin type. With the catalyst 1, (NH4)3[FeMo6O18(OH)6], various aromatic and aliphatic alkenes were successfully transformed into the corresponding epoxides with excellent yields as well as chemo- and stereo-selectivity. This catalytic system possesses the advantages of being able to avoid the use of expensive, toxic, air/moisture sensitive and commercially unavailable organic ligands. The generality of this methodology is simple to operate and exhibits high catalytic activity as well as excellent stability, which gives it the potential to be used on an industrial scale, and maybe opens a way for the catalytic oxidation reaction via inorganic-ligand coordinated iron catalysis.
- Zhou, Zhuohong,Dai, Guoyong,Ru, Shi,Yu, Han,Wei, Yongge
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supporting information
p. 14201 - 14205
(2019/10/02)
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- An Isolable and Bench-Stable Epoxidizing Reagent Based on Triazine: Triazox
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A new triazine-based oxidizing reagent, 2-hydroperoxy-4,6-diphenyl-1,3,5-triazine (Triazox), has been developed. The reagent can be synthesized from inexpensive starting materials and is a bench-stable solid that is isolable in pure form. Epoxidation of alkenes possessing acid-sensitive functionalities using Triazox proceeded in good to excellent yields. The accompanying nonacidic triazinone coproduct can be easily removed by filtration. These features indicate that Triazox is a practically useful oxidizing reagent.
- Yamada, Kohei,Igarashi, Yuki,Betsuyaku, Tatsuki,Kitamura, Masanori,Hirata, Koki,Hioki, Kazuhito,Kunishima, Munetaka
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supporting information
p. 2015 - 2019
(2018/04/16)
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- Peroxotantalate-Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide
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The efficient and environmentally benign epoxidation of allylic alcohols has been attained by using new kinds of monomeric peroxotantalate anion-functionalized ionic liquids (ILs=[P4,4,4,n]3[Ta(O)3(η-O2)], P4,4,4,n=quaternary phosphonium cation, n=4, 8, and 14), which have been developed and their structures determined accordingly. This work revealed the parent anions of the ILs underwent structural transformation in the presence of H2O2. The formed active species exhibited excellent catalytic activity, with a turnover frequency for [P4,4,4,4]3[Ta(O)3(η-O2)] of up to 285 h?1, and satisfactory recyclability in the epoxidation of various allylic alcohols under very mild conditions by using only one equivalent of hydrogen peroxide as an oxidant. NMR studies showed the reaction was facilitated through a hydrogen-bonding mechanism, in which the peroxo group (O–O) of the peroxotantalate anion served as the hydrogen-bond acceptor and hydroxyl group in the allylic alcohols served as the hydrogen-bond donor. This work demonstrates that simple monomeric peroxotantalates can catalyze epoxidation of allylic alcohols efficiently.
- Ma, Wenbao,Chen, Chen,Kong, Kang,Dong, Qifeng,Li, Kun,Yuan, Mingming,Li, Difan,Hou, Zhenshan
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p. 7287 - 7296
(2017/05/31)
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- Heterogenization of ketone catalyst for epoxidatio by low pressure plasma fluorination of silica gel supports
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Low pressure plasma was used for preparing heterogeneous organocatalysts 2-(A)-(C) suitable for dioxirane-mediated epoxidations. Heterogenization was accomplished by adsorption of the methyl perfluoroheptyl ketone (2) on fluorinated supports (A)-(C) deriving from the treatment of commercial C8-silica gel in low pressure plasma fed with fluorocarbons. Catalyst 2-(C) proved to be the most efficient one, promoting epoxidation of an array of alkenes, including unsaturated fatty esters like methyl oleate (10) and the triglyceride soybean oil (11), with the cheap potassium peroxymonosulfate KHSO5 (caroate) as a green oxidant. Notably, the perfluorinated matrix gives rise to the activation of caroate, generating singlet oxygen. Materials were characterized by infrared Attenuated Total Reflectance spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS) and Emission Scanning Electron Microscope (FESEM).
- D'Accolti, Lucia,De Vietro, Nicoletta,Fanelli, Fiorenza,Fusco, Caterina,Nacci, Angelo,Fracassi, Francesco
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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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- Manganese(II)/Picolinic Acid Catalyst System for Epoxidation of Olefins
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An in situ generated catalyst system based on Mn(CF3SO3)2, picolinic acid, and peracetic acid converts an extensive scope of olefins to their epoxides at 0 °C in 5 min, with remarkable oxidant efficiency and no evidence of radical behavior. Competition experiments indicate an electrophilic active oxidant, proposed to be a high-valent Mn = O species. Ligand exploration suggests a general ligand sphere motif contributes to effective oxidation. The method is underscored by its simplicity and use of inexpensive reagents to quickly access high value-added products.
- Moretti, Ross A.,Du Bois,Stack, T. Daniel P.
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supporting information
p. 2528 - 2531
(2016/07/06)
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- A synergistic effect of a cobalt Schiff base complex and TiO2 nanoparticles on aerobic olefin epoxidation
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In this study, a cobalt Schiff base complex and TiO2 nanoparticles exhibited a synergistic effect on the visible-light photocatalytic activity in the aerobic oxidation of various olefins in the absence of a reducing agent. The catalyst structure was found to be well preserved after the oxidation reaction and the catalyst could be reused at least five times.
- Jafarpour, Maasoumeh,Kargar, Hossein,Rezaeifard, Abdolreza
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p. 79085 - 79089
(2016/09/09)
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- Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids
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This work reports new kinds of monomeric peroxoniobate anion functionalized ionic liquids (ILs) designated as [A+][Nb=O(O-O)(OH)2] (A+ = tetrapropylammonium, tetrabutylammonium, or tetrahexylammonium cation), which have been prepared and characterized by elemental analysis, HRMS, NMR, IR, TGA, etc. With hydrogen peroxide as an oxidant, these ILs exhibited excellent catalytic activity and recyclability in the epoxidation of various allylic alcohols under solvent-free and ice bath conditions. Interestingly, subsequent activity tests and catalyst characterization together with first-principles calculations indicated that the parent [Nb=O(O-O)(OH)2]- anion has been oxidized into the anion [Nb(O-O)2(OOH)2]- in the presence of H2O2, which constitutes the real catalytically active species during the reaction; this anion has higher activity in comparison to the analogous peroxotungstate anion. Moreover, the epoxidation process of the substrate (allylic alcohol) catalyzed by [Nb(O-O)2(OOH)2]- was explored at the atomic level by virtue of DFT (density functional theory) calculations, identifying that it is more favorable to occur through a hydrogen bond mechanism, in which the peroxo group of [Nb(O-O)2(OOH)2]- serves as the adsorption site to anchor the substrate OH group by forming a hydrogen bond, while OOH as the active oxygen species attacks the C=C bond in substrates to produce the corresponding epoxide. This is the first example of the highly efficient epoxidation of allylic alcohols using a peroxoniobate anion as a catalyst.
- Chen, Chen,Yuan, Haiyang,Wang, Haifeng,Yao, Yefeng,Ma, Wenbao,Chen, Jizhong,Hou, Zhenshan
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p. 3354 - 3364
(2016/07/06)
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- Borinic Acid Catalyzed, Regioselective Chloroacylations and Chlorosulfonylations of 2,3-Epoxy Alcohols
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In the presence of a borinic acid derived catalyst, 2,3-epoxy alcohols undergo couplings with acyl and sulfonyl chlorides. This transformation directly generates O-acylated or O-sulfonylated chlorohydrin diols, with significant levels of regioselectivity for both the ring-opening and O-functionalization steps.
- Tanveer, Kashif,Jarrah, Kareem,Taylor, Mark S.
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p. 3482 - 3485
(2015/07/28)
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- Bismuth-substituted "sandwich" type polyoxometalate catalyst for activation of peroxide: Umpolung of the peroxo intermediate and change of chemoselectivity
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The epoxidation of alkenes with peroxides by WVI, MoVI, VV, and TiIV compounds is well established, and it is well accepted that the active intermediate peroxo species are electrophilic toward nucleophilic substrates. Polyoxotungstates, for example, those of the "sandwich" structure, [WZn(TM-L)2(ZnW9O34)2]q- in which TM = transition metal and L = H2O, have in the past been found to be excellent epoxidation catalysts. It has now been found that substituting the Lewis basic BiIII into the terminal position of the "sandwich" polyoxometalate structure to yield [Zn2BiIII2(ZnW9O34)2]14- leads to an apparent umpolung of the peroxo species and formation of a nucleophilic peroxo intermediate. There are two lines of evidence that support the formation of a reactive nucleophilic peroxo intermediate: (1) More electrophilic sulfoxides are more reactive than more nucleophilic sulfides, and (2) nonfunctionalized aliphatic alkenes and dienes showed ene type reactivity rather than epoxidation pointing toward "dark" formation of singlet oxygen from the nucleophilic intermediate peroxo species. Allylic alcohols reacted much faster than alkenes but showed chemoselectivity toward C-H bond activation of the alcohol and formation of aldehydes or ketones rather than epoxidation. This explained via alkoxide formation at the BiIII center followed by oxidative β-elimination.
- Amanchi, Srinivasa Rao,Khenkin, Alexander M.,Diskin-Posner, Yael,Neumann, Ronny
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p. 3336 - 3341
(2015/06/16)
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- Synthesis, characterization, magnetic and catalytic properties of a ladder-shaped MnII coordination polymer
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[Mn(LH)(H2O)]n {1, where LH2- is the dianion of N-(4-carboxybenzyl)iminodiacetic acid} has been synthesized and its crystal structure has been determined. The crystal of 1 is built from 1D polymeric ladder-shaped chains that extend to a 3D supramolecular architecture through H-bonds. The compound was characterized with spectroscopic and physicochemical techniques. Variable-temperature magnetic data suggest that there are weak antiferromagnetic interactions. Compound 1 has been evaluated as a heterogeneous oxidation catalyst. It catalyzes alkene epoxidation selectively in relatively high yields.
- Lymperopoulou, Smaragda,Papastergiou, Maria,Louloudi, Maria,Raptopoulou, Catherine P.,Psycharis, Vassilis,Milios, Constantinos J.,Plakatouras, John C.
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p. 3638 - 3644
(2015/05/05)
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- Regioselective Cleavage of Electron-Rich Double Bonds in Dienes to Carbonyl Compounds with [Fe(OTf)2(mix-BPBP)] and a Combination of H2O2 and NaIO4
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A method for the regioselective transformation of dienes to carbonyl compounds has been developed. Electron-rich olefins react selectively to yield valuable aldehydes and ketones. The method is based on the catalyst [Fe(OTf)2(mix-BPBP)] with an oxidant combination of H2O2 (1.0 equiv.) and NaIO4 (1.5 equiv.); it uses mild conditions and short reaction times, and it outperforms other olefin cleavage methodologies. The combination of an Fe-based catalyst, [Fe(OTf)2(mix-BPBP)], and the oxidants H2O2 and NaIO4 can discriminate between electronically different double bonds and oxidatively cleave the electron-rich bond in dienes to yield aldehydes and ketones in a regioselective manner. The reaction requires mild conditions (0-50 C) and short reaction times (70 min).
- Spannring, Peter,Yazerski, Vital A.,Chen, Jianming,Otte, Matthias,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.,Klein Gebbink, Robertus J. M.
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p. 3462 - 3466
(2015/08/06)
-
- An ionic liquid immobilized copper complex for catalytic epoxidation
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This article brings into focus an in situ strategy of immobilization of a copper complex onto an ionic liquid support. A practical method of olefin and terpene epoxidation by immobilizing a copper complex and 1-ethyl-3-methylimidazolium hexafluorophosphate and using H2O2 as the terminal oxidant is developed. The advantageous properties of this catalytic system redefine an exceptionally clean environment for catalytic epoxidations.
- Dileep,Rudresha
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p. 65870 - 65873
(2015/08/18)
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- Catalytic activity and selectivity of reusable α-MoO3 nanobelts toward oxidation of olefins and sulfides using economical peroxides
-
The novel catalytic activity of α-MoO3 nanobelts prepared by a new and safe sol-gel method for the epoxidation of olefins and oxidation of sulfides to sulfoxides using H2O2 in ethanol as a safe solvent has been exploited. The reactions also proceeded efficiently in the presence of tert-butyl hydroperoxide (TBHP). Good/high yields and excellent selectivity resulted. The ammonia TPD profile demonstrated strong acidic sites in synthesized α-MoO3 nanobelts, which generated different catalytic activity than the bulk material. The separation and reuse of this heterogeneous nanocatalyst was simple, effective and economical in the presented oxidation methods.
- Jafarpour, Maasoumeh,Ghahramaninezhad, Mahboube,Rezaeifard, Abdolreza
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p. 1601 - 1608
(2014/01/06)
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- Synthesis, Characterization, Magnetic and Catalytic Properties of a Ladder-Shaped MnII Coordination Polymer
-
[Mn(LH)(H2O)]n {1, where LH2- is the dianion of N-(4-carboxybenzyl)iminodiacetic acid} has been synthesized and its crystal structure has been determined. The crystal of 1 is built from 1D polymeric ladder-shaped chains that extend to a 3D supramolecular architecture through H-bonds. The compound was characterized with spectroscopic and physicochemical techniques. Variable-temperature magnetic data suggest that there are weak antiferromagnetic interactions. Compound 1 has been evaluated as a heterogeneous oxidation catalyst. It catalyzes alkene epoxidation selectively in relatively high yields.
- Lymperopoulou, Smaragda,Papastergiou, Maria,Louloudi, Maria,Raptopoulou, Catherine P.,Psycharis, Vassilis,Milios, Constantinos J.,Plakatouras, John C.
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p. 3638 - 3644
(2015/04/27)
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- Synthesis of functionalized octahydroindoles related to daphnyphyllum alkaloids
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Functionalized octahydroindoles were synthesized from (±)-cyclohex- 2-en-1-ol as potential intermediates for convergent syntheses of several alkaloids from plants of the Daphnyphyllum genus. Georg Thieme Verlag Stuttgart, New York.
- Dorich, Stéphane,Del Valle, Juan R.,Hanessian, Stephen
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p. 799 - 804
(2014/04/03)
-
- Cycloalkane Derivatives
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Disclosed herein are therapeutic agents and/or preventive agents for pain or therapeutic agents and/or preventive agents for a sodium channel associated disease. The present invention provides compounds represented by the following formula (I) or pharmacologically acceptable salts thereof:
- -
-
Paragraph 1184; 1185
(2014/03/21)
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- Selective oxidation of sulfides and olefins by a manganese (III) complex containing an N,O-type bidentate oxazine ligand
-
A new manganese(III) complex [(N-O)2Mn(OAc)] was synthesized using 2-(2'-hydroxyphenyl)-5,6-dihydro-1,3-oxazine (N-O) as a bidentate O, N donor. The complex has been characterized by elemental analysis, IR, UV-vis spectroscopy, and X-ray structure analysis. Oxidation of sulfides and epoxidation of olefins, respectively, to their corresponding sulfoxides and epoxides were conducted by this catalyst using urea hydrogen peroxide as oxidant at room temperature under air. The catalyst is efficient in oxidation reactions giving high yields and selectivities.
- Amini, Mojtaba,Bagherzadeh, Mojtaba,Moradi-Shoeili, Zeinab,Boghaei, Davar M.,Ellern, Arkady,Woo, L. Keith
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p. 464 - 472
(2013/08/24)
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- Syntheses, X-ray structures, and catalytic oxidations of dioxomolybdenum(VI) complexes with tridentate benzohydrazones
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Two new dioxomolybdenum(VI) complexes, [MoO2L 1(CH30H)]CH30H (1) and [MoO2L 2(CH30H)] (2), where L1 and L2 are dianionic forms of N'-(3-bromo-2-hydroxybenzylidene)-4-hydroxybenzohydrazide and N'-(2-hydroxybenzylidene)-2-hydroxy-3-methylbenzohydrazide, respectively, have been synthesized. The complexes have been characterized by elemental analyzes, IR spectra, molar conductance data, and single crystal X-ray determination. Mo in each complex is octahedral. The crystals of the complexes are stabilized by hydrogen bonds and weak π π stacking interactions. The complexes function as effective olefin epoxidation catalysts with hydrogen peroxide as oxidant and sodium hydrogen carbonate as a co-catalyst at room temperature.
- He, Xiao-Qiang
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p. 966 - 976
(2013/07/28)
-
- SELECTIVE KINASE INHIBITORS
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Provided are pyrimidine compounds for inhibiting of Syk kinase, intermediates used in making such compounds, methods for their preparation, pharmaceutical compositions thereof, methods for inhibition Syk kinase activity, and methods for treating conditions mediated at least in part by Syk kinase activity.
- -
-
Paragraph 0733
(2013/06/06)
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- New molybdenum(VI) complex with ONS-donor thiosemicarbazone ligand: Preparation, structural characterization, and catalytic applications in olefin epoxidation
-
New dioxomolybdenum(VI) complex was prepared by reacting 1-(2,4-dihydroxybenzylidene)-N-methyl-N-phenylthiosemicarbazone (H2L) as ligand and [MoO2(acac)2] in acetonitrile solution. The doubly deprotonated ligand is coordinated to molybdenum through sulfur atom, hydrazinic nitrogen atom and phenolic oxygen atom. The resulting complex with the formula [MoO2L(CH3CN)] which contains an acetonitrile molecule in sixth site of coordination, was characterized by elemental analyses, 1H NMR, IR and electronic spectroscopic studies and single crystal X-ray diffraction analysis. This complex was tested as a catalyst for the homogeneous epoxidation of olefins using tert-butyl hydrogen peroxide (TBHP) as an oxidant. The catalyst shows efficient reactivity in the olefins epoxidation reactions giving high yield and selectivity under atmospheric conditions, in most cases.
- Moradi-Shoeili, Zeinab,Boghaei, Davar M.,Amini, Mojtaba,Bagherzadeh, Mojtaba,Notash, Behrouz
-
-
- Dioxirane-mediated heterogeneous epoxidations with potassium caroate: A solid catalyst bearing anchored ketone moieties
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A new hybrid material (3) consisting of trifluoromethyl ketone (TFMK) moieties, immobilized on silica through an appropriate spacer, was synthesized and characterized. Lacking easily oxidizable functionalities in the spacer chain, this material proved to be an excellent catalyst in heterogeneous epoxidations with potassium caroate (KHSO5), surpassing other reported catalysts in performance and stability. The efficiency of silica-supported catalyst 3 could be assessed upon carrying out the selective dioxirane-mediated epoxidation of representative alkenes in high yields. The solid catalyst could then be recovered and reused in a number of consecutive oxidation cycles. The synthesis of a new hybrid, which presents trifluoromethyl ketone moieties anchored on silica gel through a short spacer, is reported. Lacking easily oxidizable functionalities in the linker chain, this solid material is an efficient catalyst in dioxirane-mediated heterogeneous epoxidations using potassium caroate. Copyright
- D'Accolti, Lucia,Annese, Cosimo,De Riccardis, Alberto,De Giglio, Elvira,Cafagna, Damiana,Fanelli, Fiorenza,Fusco, Caterina
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p. 4616 - 4621,6
(2020/08/31)
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- Economical oxygenation of olefins and sulfides catalyzed by new molybdenum(VI) tridentate schiff base complexes: Synthesis and crystal structure
-
New cis-dioxomolybdenum(VI) complexes (MoO2YxCH 3OH) were synthesized using MoO2(acac)2 and 2[(1-hydroxy-2-methylpropane-2-ylimino)methyl]phenol derivatives as tridentate ONO donor Schiff base ligands (H2Yx). MoY1 was crystallized in orthorhombic space group Pbca. The epoxidation of olefins using tert-butyl hydroperoxide and oxidation of sulfides to the sulfoxides by hydrogen peroxide were efficiently enhanced by the catalytic activity of title Mo VI complexes with excellent selectivity. The high efficiency and relative stability of the catalysts was observed by turnover number and UV/Vis investigations. The electron-rich and bulky ligands promoted the effectiveness of the catalysts. Copyright
- Rezaeifard, Abdolreza,Jafarpour, Maasoumeh,Raissi, Heidar,Alipour, Mahboubeh,Stoeckli-Evans, Helen
-
experimental part
p. 1023 - 1030
(2012/08/07)
-
- Epoxidation of olefins with a silica-supported peracid in supercritical carbon dioxide under flow conditions
-
Anhydrous 2-percarboxyethyl-functionalized silica (2b), a recyclable supported peracid, is a suitable reagent to perform the epoxidation of alkenes 1 in supercritical carbon dioxide at 250 bar and 40 °C under flow conditions. This procedure simplifies the isolation of the reaction products and uses only carbon dioxide as a solvent under mild conditions. The solid reagent 2b can be easily recycled by a reaction with 30% hydrogen peroxide in an acid medium.
- Mello, Rossella,Alcalde-Aragones, Ana,Olmos, Andrea,Gonzalez-Nunez, Maria Elena,Asensio, Gregorio
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experimental part
p. 4706 - 4710
(2012/07/28)
-
- Epoxidation of olefins with a silica-supported peracid
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Anhydrous [2-percarboxyethyl] functionalized silica (2a) is an advantageous oxidant for performing the epoxidation of olefins 1. Epoxides 3 do not undergo the ring-opening reactions catalyzed by the acidic silica surface, except for particularly activated cases such as styrene oxide. The hydrophilic and acidic character of the silica surface does not interfere with the directing effects exerted by allylic H-bond acceptor substituents. The alkenes 1 carrying hydroxyl groups react with silica-supported peracid 2a faster than unsubstituted alkenes, thus reversing the trend known for reactions with soluble peracids. These results are attributed to the H-bond interactions of substrate 1 with the silanol and carboxylic acid groups bonded to the silica surface.
- Mello, Rossella,Alcalde-Aragones, Ana,Gonzalez Nunez, Maria Elena,Asensio, Gregorio
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experimental part
p. 6409 - 6413
(2012/10/08)
-
- Zinc(II) containing γ-keggin sandwich-type silicotungstate: Synthesis in organic media and oxidation catalysis
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Zinc in: Polyoxometalate 1 reacts with Zn2+ ions in acetone to form a novel sandwichtype POM 2 in almost quantitative yield. The H2O2-based oxidation of secondary alcohols with 2 efficiently proceeds, with an activity and chemoselectivity that is very different from those of tungsten-based catalysts including 1 (see scheme; green Zn).
- Kikukawa, Yuji,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information; experimental part
p. 6096 - 6100
(2010/11/05)
-
- Synthesis, characterization and pronounced epoxidation activity of cis-dioxo-molybdenum(VI) tridentate Schiff base complexes using tert-butyl hydroperoxide
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The synthesis and catalytic performance of novel cis-dioxo-Mo(VI) complexes containing simple ONO tridentate Schiff base ligands in the epoxidation of various olefins using tert-butyl hydroperoxide in desired times with excellent chemo- and stereoselectivity have been described. The study of turnover numbers and the UV-Vis spectra of the Mo complexes in the present epoxidation system indicate well the high efficiency and stability of the catalysts during the reaction. The electron-deficient and bulky groups on the salicylidene ring of the ligand promote the effectiveness of the catalyst.
- Rezaeifard, Abdolreza,Sheikhshoaie, Iran,Monadi, Niaz,Alipour, Mahboubeh
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experimental part
p. 2703 - 2709
(2011/01/10)
-
- Synthesis, crystal structure, and catalytic properties of novel dioxidomolybdenum(VI) complexes with tridentate schiff base ligands in the biomimetic and highly selective oxygenation of alkenes and sulfides
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Four novel dioxidomolybdenum(VI) complexes [MoO2(L x)(CH3OH)] have been synthesized, using 2[(E)-(2-hydroxy-2-phenylethylimino)methyl]phenol derivatives as tridentate ONO donor Schiff base ligands (H2Lx) and MoO 2(acac)2. A monoclinic space group was determined by X-ray crystallography from single-crystal data of a sample of these new complexes. The epoxidation of alkenes by using tert-butyl hydroperoxide and oxidation of sulfides to sulfoxides by urea hydrogen peroxide were efficiently enhanced with excellent selectivity under the catalytic influence these new MoVI complexes. The high efficiency and relative stability of the catalysts have been observed, by turnover numbers and UV/Vis investigations. The electron-poor and bulky ligands promoted the effectiveness of the catalysts. 2010 Wiley-VCH Verlag GmbH & Co. KGaA.
- Rezaeifard, Abdolreza,Sheikhshoaie, Iran,Monadi, Maz,Stoeckli-Evans, Helen
-
experimental part
p. 799 - 806
(2010/07/04)
-
- Hydrogen-bond-assisted epoxidation of homoallylic and allylic alcohols with hydrogen peroxide catalyzed by selenium-containing dinuclear peroxotungstate
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The reaction of peroxotungstates (H2WO4 + H 2O2) with H2SeO4 gave the novel seleniumcontaining dlnuclear tungsten species, (TBA)2[SeO 4{WO(O2)2}2] (I, TBA = [(n-C 4H9)4N]+), which was characterized by elemental analysis, IR, Raman, UV-vls, 77Se NMR, 183W NMR, and CSI-MS. Various kinds of homoallyllc and allyllc alcohols were efficiently epoxldlzed to the corresponding epoxy alcohols In high yields with 1 equlv. H2O2 with respect to thesubstrates. Compound I showed the highest catalytic activity for H 2O2-based epoxldatlon of homoallyllc and allyllc alcohols among selenium and tungsten complexes. The turnover frequency reachedup to 150 h-1 In a 10 mmol-scale epoxldatlon of c/s-3-hexen1 -ol and this value was the highest among those reported for the translt lon-metal catalyzed epoxldatlon of homoallyllc alcohols with H2O2. The kinetic, mechanistic, computational studies showed that the stabilization of the transition-state by the hydrogen bonding between I and the substrates results In the high reactivity for the l-catalyzed epoxldatlon of homoallyllc and allyllc alcohols. The nature of the hetero atoms In the dland tetranuclear peroxotungstates with XO 4n- ligands (X = As(V), P(V), S(VI), SI(IV), etc.) was crucial In controlling the Lewis acidity of the peroxotungstates, which significantly affects their electrophlllc oxygen transfer reactivity. Allthe data of the structural, kinetic, spectroscopic, and computational c omparison show that the dlmerlc peroxotungstate unit, {WO(O2)2} 2, In I Is activated by the SeO42- ligand.
- Kamata, Keigo,Hirano, Tomohisa,Kuzuya, Shinjiro,Mizuno, Noritaka
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scheme or table
p. 6997 - 7004
(2009/09/30)
-
- Synthesis of conformationally locked carbocyclic nucleosides built on a thiabicyclo[3.1.0]hexane system as a pseudosugar surrogate
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The synthesis of prototype models of purine and pyrimidine carbanucleosides built on a 6-thiabicyclo[3.1.0]hexane system as pseudosugar moiety has been investigated. These pyrimidine carbanucleosides proved to be very stable compounds, in contrast to the parent epoxy analogs, which experienced epoxide ring-opening due to intramolecular enol base attack. In addition, as the synthesis of a thiirane moiety fused to a five-membered ring is not a trivial synthetic task, validation and optimization of the existing methods for episulfide preparation were required to access the committed synthetic precursor of the title compounds: (±)-(1RS,2RS,5SR)-6-thiabicyclo[3.1.0]hexan-2- ol, compound 28. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Elhalem, Eleonora,Comin, Maria J.,Rodriguez, Juan B.
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p. 4473 - 4482
(2007/10/03)
-
- Polyoxovanadometalate-catalyzed selective epoxidation of alkenes with hydrogen peroxide
-
The bis(μ-hydroxo)-bridged dioxovanadium site in [γ-1,2-H 2SiV2W10O40]4 catalyzes the epoxidation of alkenes in the presence of only one equivalent of H 2O2 with a high yield of epoxide, high efficiency of H2O2 utilization, unusual regioselectivity, and unprecedented diastereoselectivity (see picture). (Chemical Equation Presented)
- Nakagawa, Yoshinao,Kamata, Keigo,Kotani, Miyuki,Yamaguchi, Kazuya,Mizuno, Noritaka
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p. 5136 - 5141
(2007/10/03)
-
- Dichlororuthenium(IV) complex of meso-Tetrakis(2,6-dichlorophenyl) porphyrin: Active and robust catalyst for highly selective oxidation of arenes, Unsaturated steroids, and electron-deficient alkenes by using 2,6-dichloropyridine N-oxide
-
[RuIV(2,6-Cl2tpp)Cl2], prepared in 90% yield from the reaction of [RuVI(2,6-Cl2tpp)O2] with Me3SiCl and structurally characterized by X-ray crystallography, is markedly superior to [RuIv(tmp)Cl2], [RuIV(ttp)Cl2], and [RuII(por)(CO)] (por = 2,6-Cl2tpp, F20-tpp, F28-tpp) as a catalyst for alkene epoxidation with 2,6-Cl2pyNO (2,6Cl2tpp = meso-tetrakis(2,6-dichlorophenyl)porphyrinato dianion; tmp = meso-tetramesitylporphyrinato dianion; ttp = meso-tetrakis(p-tolyl)porphyrinato dianion; F20-tpp = meso-tetrakis(pentafluorophenyl)porphyrinato dianion; F28-tpp = 2,3,7,8,12,13,17,18-octafluoro-5,10,15,20- tetrakis(pentafluorophenyl)-porphyrinato dianion). The "[Ru IV(2,6-Cl2tpp)Cl2] + 2,6-Cl 2pyNO" protocol oxidized, under acid-free conditions, a wide variety of hydrocarbons including 1) cycloalkenes, conjugated enynes, electron-deficient alkenes (to afford epoxides), 2) arenes (to afford quinones), and 3) Δ5-unsaturated steroids, Δ4-3- ketosteroids, and estratetraene derivatives (to afford epoxide/ketone derivatives of steroids) in up to 99% product yield within several hours with up to 100% substrate conversion and excellent regio- or diastereoselectivity. Catalyst [RuIv(2,6-Cl2tpp)Cl2] is remarkably active and robust toward the above oxidation reactions, and turnover numbers of up to 6.4 × 103, 2.0 × 104, and 1.6 × 104 were obtained for the oxidation of α,β-unsaturated ketones, arenes, and Δ5-unsaturated steroids, respectively.
- Zhang, Jun-Long,Che, Chi-Ming
-
p. 3899 - 3914
(2007/10/03)
-
- Diastereoselective epoxidation of allylically substituted alkenes using metalloporphyrin catalysts
-
Diastereoselective epoxidation of allylically substituted alkenes using metalloporphyrins as catalyst provides high trans-selectivities (i.e., trans-:cis-epoxide ratio). A diversity of cycloalkenes bearing different allylic substituents are shown to be efficiently epoxidized to afford the corresponding trans-epoxides with excellent trans-selectivities (up to >98%) and good yields (up to 99%). Acyclic allylic alkenes bearing different allylic substituents are efficiently epoxidized to afford the corresponding erythro-epoxides with good erythro-selectivities. The metalloporphyrin-catalyzed reactions exhibit up to 20 times higher trans-selectivities than the conventional method using m-chloroperoxybenzoic acid as oxidant.
- -
-
Page/Page column 4
(2008/06/13)
-
- Formation of dihydroxyselenides from allylic alcohols and their conversion to β-hydroxy epoxides via substitution of a phenylselenonyl group
-
Hydroxyselenation of allylic alcohols occurs with high regio- and stereoselectivity to give β,β′-dihydroxyphenylselanyl adducts in high yields. An exception is the reaction of the terminal alcohol, 2-methylprop-2-en-1-ol, which forms only a 1,2-diol product. Generally, the addition is Markovnikov in orientation, but the fact that one anti-Markovnikov addition is observed and that addition to 1,2-disubstituted alkenes shows a strong preference for one regioisomer suggests that an interaction of the allylic alcohol with the selenium atom of the reaction intermediate (which weakens the Cβ-Se bond in the intermediate) is also an important factor in determining the preference for addition of the phenylselanyl group to the double bond carbon nearest the allylic alcohol. The hydroxyselenated adducts of allylic alcohols can be readily converted to β-hydroxy epoxides in good yields via oxidation with m-chloroperbenzoic acid to a selenone and subsequent treatment with base. Hydroxyselenation of crotyl acetate and 3-acetoxycyclohexene is more regiocatholic than hydroxyselenation of the corresponding allylic alcohols. It appears that the known selectivity of additions of phenylselanyl chloride to these acetates in organic solvents is lost when water or a Lewis acid complexes to the acetate group.
- Cooper, Matthew A.,Ward, A. David
-
p. 7963 - 7972
(2007/10/03)
-
- Highly selective, recyclable epoxidation of allylic alcohols with hydrogen peroxide in water catalyzed by dinuclear peroxotungstate
-
The highly chemo-, regio-, and diastereoselective and stereospecific epoxidation of various allylic alcohols with only one equivalent of hydrogen peroxide in water can be efficiently catalyzed by the dinuclear peroxotungstate, K2[{W(=O)(O2)2(H2O)} 2(μ-O)]· 2H2O (1). The catalyst is easily recycled while maintaining its catalytic performance. The catalytic reaction mechanism including the exchange of the water ligand to form the tungsten-alcoholate species followed by the insertion of oxygen to the carbon-carbon double bond, and the regeneration of the dinuclear peroxotungstate with hydrogen peroxide is proposed. The reaction rate shows first-order dependence on the concentrations of allylic alcohol and dinuclear peroxotungstate and zero-order dependence on the concentration of hydrogen peroxide. These results, the kinetic data, the comparison of the catalytic rates with those for the stoichiometric reactions, and kinetic isotope effects indicate that the oxygen transfer from a dinuclear peroxotungstate to the double bond is the rate-limiting step for terminal allylic alcohols such as 2-propen-1-o1 (1a).
- Kamata, Keigo,Yamaguchi, Kazuya,Mizuno, Noritaka
-
p. 4728 - 4734
(2007/10/03)
-
- Highly diastereoselective epoxidation of allyl-substituted cycloalkenes catalyzed by metalloporphyrins
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Highly diastereoselective epoxidations of allyl-substituted cycloalkenes including allylic alcohols, esters, and amines using sterically bulky metalloporphyrins [Mn(TDCPP)Cl] (1) and [Ru(TDCPP)CO] (2) as catalysts have been achieved. The "1 + H2O2" and "2 + 2,6-Cl2pyNO" protocols afforded trans-epoxides selectively in good yields (up to 99%) with up to >99:1 trans-selectivity.
- Chan, Wing-Kei,Liu, Peng,Yu, Wing-Yiu,Wong, Man-Kin,Che, Chi-Ming
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p. 1597 - 1599
(2007/10/03)
-
- Selective oxidations of allylic alcohols using vanadyl and cobalt(II) alkyl phosphonate modified silicas
-
A range of allylic alcohols can be selectively oxidised to either the corresponding epoxide or the enone in good yields using catalytic quantities of vanadyl or cobalt(II) alkyl phosphonate modified silicas, CoEPS3 and VOEPS3 and tert-butyl hydroperoxide.
- Jurado-Gonzalez, Magdalena,Sullivan, Alice C.,Wilson, John R.H.
-
p. 4465 - 4468
(2007/10/03)
-
- Highly efficient catalytic asymmetric epoxidation of allylic alcohols by an oxovanadium-substituted polyoxometalate with a regenerative TADDOL-derived hydroperoxide
-
(Matrix presented) The oxovanadium(IV) sandwich-type POM catalyzes the chemo-, regio-, and stereoselective epoxidation of allylic alcohols by chiral hydroperoxides with very high catalytic efficiency (up to 42 000 TON), a potentially valuable oxidation for the development of sustainable processes. By using the sterically demanding, TADDOL-derived hydroperoxide TADOOH as the chiral oxygen source, enantiomeric ratios (er) of up to 95:5 have been achieved.
- Adam, Waldemar,Alsters, Paul L.,Neumann, Ronny,Saha-Moeller, Chantu R.,Seebach, Dieter,Zhang, Rui
-
p. 725 - 728
(2007/10/03)
-