- Dioxidomolybdenum(VI) and -tungsten(VI) complexes with tripodal amino bisphenolate ligands as epoxidation and oxo-transfer catalysts
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The molybdenum(VI) and tungsten(VI) complexes [MO2(L)] (M?=?Mo (1), W (2), H2L?=?bis(2-hydroxy-3,5-di-tert-butybenzyl)morpholinylethylamine) were synthesized and the complexes were used to catalyze oxotransfer reactions, viz. sulfoxi
- Hossain, Md. Kamal,Schachner, J?rg A.,Haukka, Matti,Lehtonen, Ari,M?sch-Zanetti, Nadia C.,Nordlander, Ebbe
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- Dysprosium-doped zinc tungstate nanospheres as highly efficient heterogeneous catalysts in green oxidation of terpenic alcohols with hydrogen peroxide
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A green route to oxidize terpenic alcohols (nerol and geraniol) with H2O2over a solid catalyst was developed. The Dy-doped ZnWO4catalyst was synthesized by coprecipitation and microwave-assisted hydrothermal heating, containing different dysprosium loads. All the catalysts were characterized through infrared spectroscopy, powder X-ray diffraction, surface area and porosimetry, transmission electronic microscopy image, andn-butylamine potentiometric titration analyses. The influence of main reaction parameters such as temperature, the stoichiometry of reactants, loads, and catalyst nature was assessed. ZnWO42.0 mol% Dy was the most active catalyst achieving the highest conversion (98%) and epoxide selectivity (78%) in nerol oxidation. The reaction scope was extended to other terpenic alcohols (i.e., geraniol, borneol, and α-terpineol). The highest activity of ZnWO42.0 mol% Dy was assigned to the lower crystallite size, higher surface area and pore volume, higher acidity strength and the greatest dysprosium load.
- Batalha, Daniel Carreira,Mesquita Borges, Kellen Cristina,de Fátima Gon?alves, Rosana,de Matos Rodrigues, Murillo Henrique,Godinho, Mário Júnior,Fajardo, Humberto Vieira,de Oliveira Bruziquesi, Carlos Giovani,da Silva, Márcio José
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p. 6661 - 6670
(2021/04/22)
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- Unraveling the role of the lacunar Na7PW11O39 catalyst in the oxidation of terpene alcohols with hydrogen peroxide at room temperature
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In this work, we have assessed the activity of various Keggin heteropolyacid (HPA) salts in a new one-pot synthesis route of valuable products, which were obtained from the oxidation of terpenic alcohols (i.e., aldehyde, epoxide, and diepoxide), using a green oxidant (i.e., hydrogen peroxide) at mild conditions (i.e., room temperature). Lacunar Keggin HPA sodium salts were the goal catalysts investigated in this reaction. Starting from the HPAs (H3PW12O40, H3PMo12O40, and H4SiW12O40), we synthesized lacunar sodium salts (Na7PW11O39, Na7PW11O39 and Na8SiW11O39) and a saturated salt (Na3PW12O40). All of them were investigated in oxidation reactions in a homogeneous phase with nerol as a model molecule. Na7PW11O39 was the most active and selective towards the oxidation products. All the catalysts were characterized by FT-IR, TG/DSC, BET, XRD, and SEM-EDS analyses and potentiometric titration. The main reaction parameters were assessed. Geraniol, α-terpineol, β-citronellol and borneol were also successfully oxidized. Special attention was dedicated to correlating the composition and properties of the catalysts with their activity.
- Vilanculo, Castelo B.,Da Silva, Márcio J.
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p. 2813 - 2820
(2020/03/03)
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- One-pot synthesis at room temperature of epoxides and linalool derivative pyrans in monolacunary Na7PW11O39-catalyzed oxidation reactions by hydrogen peroxide
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In this work, we describe a new one-pot synthesis route of valuable linalool oxidation derivatives (i.e., 2-(5-methyl-5-vinyltetrahydrofuran-2-yl propan-2-ol) (1a)), 2,2,6-trimethyl-6-vinyltetrahydro-2H-pyran-3-ol (1b) and diepoxide (1c), using a green oxidant (i.e., hydrogen peroxide) under mild conditions (i.e., room temperature). Lacunar Keggin heteropolyacid salts were the catalysts investigated in this reaction. Among them, Na7PW11O39 was the most active and selective toward oxidation products. All the catalysts were characterized by FT-IR, TG/DSC, BET, XRD analyses and potentiometric titration. The main reaction parameters were assessed. Special attention was dedicated to correlating the composition and properties of the catalysts and their activity.
- Da Silva, Márcio J.,Teixeira, Milena Galdino,Vilanculo, Castelo B.,Villarreal, Jesus Avendano
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p. 7691 - 7697
(2020/03/10)
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- Method for synthesizing carvacrol from dipentene dioxide
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The invention discloses a method for synthesizing carvacrol from dipentene dioxide. The method comprises the following steps: step 1, utilizing the dipentene dioxide as a raw material and performing reducing reaction in a solvent A through the action of ammonium formate to obtain alpha,alpha,6-trimethyl-7-oxa bicyclo(4.1.0)heptane-3-methyl alcohol under the situations of hydrogen pressurization and utilizing Pd/C as a catalyst; step 2, performing dehydrating and rearranging reaction on the alpha,alpha,6-trimethyl-7-oxa bicyclo(4.1.0)heptane-3-methyl alcohol obtained in step 1 under acid catalysis to obtain iso-dihydrocarvone; step 3, dissolving the iso-dihydrocarvone obtained in step 2 and a carbon-based compound catalyst into a solvent and heating the mixture to generate dehydrogenation oxidation reaction, generating carvacrol, filtering the carvacrol to separate the carbon-based compound catalyst and performing reduced pressure rectification on filtrate to obtain a carvacrol finishedproduct. The Pd/C, the acid, the carbon-based compound catalyst and the solvent in the method disclosed by the invention can all be recycled, so that cost is reduced; the raw material of the dipentene dioxide in the method disclosed by the invention is an auxiliary product of the company, so that regeneration and comprehensive utilization of byproducts are achieved, and economic value of the byproducts is improved.
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Paragraph 0014; 0016; 0017; 0018
(2019/01/24)
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- Method for synthesizing carvacrol from dipentene dioxide
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The invention discloses a method for synthesizing carvacrol from dipentene dioxide. The method comprises the following steps: step 1, utilizing the dipentene dioxide as a raw material and reducing thedipentene dioxide in a solvent A through a sodium borohydride water solution to obtain alpha,alpha,6-trimethyl-7-oxa bicyclo(4.1.0)heptane-3-methyl alcohol and 1,3,3-trimethyl-2-oxa bicyclo(2.2.2)octane-6-alcohol; step 2, dehydrating and rearranging the alpha,alpha,6-trimethyl-7-oxa bicyclo(4.1.0)heptane-3-methyl alcohol and 1,3,3-trimethyl-2-oxa bicyclo(2.2.2)octane-6-alcohol which are obtainedin step 1 through acid catalysis to obtain iso-dihydrocarvone; step 3, dissolving the iso-dihydrocarvone obtained in step 2 and a carbon-based compound catalyst into a solvent and heating the mixtureto generate dehydrogenation oxidation reaction, generating carvacrol, filtering the carvocrol to separate the carbon-based compound catalyst and performing reduced pressure rectification on filtrate to obtain a carvacrol finished product. The acid, the carbon-based compound catalyst and the solvent in the method disclosed by the invention all can be recycled, so that cost is reduced; the raw material of the dipentene dioxide in the method disclosed by the invention is an auxiliary product of the company, so that regeneration and comprehensive utilization of byproducts are achieved, and economic value of the byproducts is improved.
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Paragraph 0017; 0019; 0021; 0022
(2019/01/24)
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- Catalytic epoxidation using dioxidomolybdenum(VI) complexes with tridentate aminoalcohol phenol ligands
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Reaction of the tridentate aminoalcohol phenol ligands 2,4-di-tert-butyl-6-(((2 hydroxyethyl)(methyl)amino)methyl)phenol (H2L1) and 2,4-di-tert-butyl-6-(((1-hydroxybutan-2-yl)amino)methyl)phenol (H2L2) with [MoO2(acac)2] in methanol solutions resulted in the formation of [MoO2(L1)(MeOH)] (1) and [MoO2(L2)(MeOH)] (3), respectively. In contrast, the analogous reactions in acetonitrile afforded the dinuclear complexes [Mo2O2(μ-O)2(L1)2] (2) and [Mo2O2(μ-O)2(L2)2] (4). The corresponding reactions with the potentially tetradentate ligand 3-((3,5-di-tert-butyl-2-hydroxybenzyl)(methyl)amino)propane-1,2-diol (H3L3) led to the formation of the mononuclear complex [MoO2(L3)(MeOH)] (5) in methanol while in acetonitrile solution a trinuclear structure [Mo3O3(μ-O)3(L3)3] (6) was obtained. In both cases, the ligand moiety L3 coordinated in a tridentate fashion. The catalytic activities of complexes 1–6 in epoxidation of five different olefins, S1-5, with tert-butyl hydroperoxide and hydrogen peroxide were studied. The catalytic activities were found to be moderate to good for the reaction of substrate cis-cyclooctene S1, while all complexes were less active in the epoxidation of the more challenging substrates S2-5. The molecular structures of 1, 2, 4 and 6 were determined by single crystal X-ray diffraction analyses.
- Hossain, Md. Kamal,Schachner, J?rg A.,Haukka, Matti,M?sch-Zanetti, Nadia C.,Nordlander, Ebbe,Lehtonen, Ari
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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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p. 209 - 219
(2017/11/15)
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- Dioxomolybdenum(VI) and -tungsten(VI) Complexes with Multidentate Aminobisphenol Ligands as Catalysts for Olefin Epoxidation
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The synthesis of four molybdenum and tungsten complexes bearing tetradentate tripodal amino bisphenolate ligands with either hydroxyethylene (1a) or hydroxyglycolene (1b) substituents is reported. The molybdenum dioxo complexes [MoO2L] (L = 2a, 2b) and tungsten complexes [WO2L] (3a, 3b) were synthesized using [MoO2(acac)2] and [W(eg)3] (eg = 1,2-ethanediolato, ethylene glycolate), respectively, as precursors. All complexes were characterized by spectroscopic means as well as by single-crystal X-ray diffraction analyses. The latter reveal, in all cases, hexacoordinate complexes in which the hydrogen atom of the hydroxy group is involved in hydrogen bonding with one of the metal oxo groups. In the case of the glycol substituent, the ether oxygen atom is coordinated to the metal whereas the hydroxy group remains uncoordinated. The complexes were tested as catalysts in the epoxidation of cyclooctene under eco-friendly conditions, using an aqueous solution of H2O2 as the oxidant and dimethyl carbonate (DMC) as solvent or neat conditions, as substitutes for chlorinated solvents. Molybdenum complexes 2a and 2b showed good catalytic activity using H2O2 without added solvent, and tungsten complexes 3a and 3b showed very high activity in the epoxidation of cyclooctene using H2O2 and DMC as solvents. Four new molybdenum and tungsten complexes bearing tetradentate tripodal amino bisphenolate ligands with either hydroxyethylene or hydroxyglycolene substituents were synthesized and found to catalyze olefin epoxidation reactions under eco-friendly conditions.
- Dup, Antoine,Hossain, Md. Kamal,Schachner, J?rg A.,Belaj, Ferdinand,Lehtonen, Ari,Nordlander, Ebbe,M?sch-Zanetti, Nadia C.
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p. 3572 - 3579
(2015/08/06)
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- 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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- Grafted non-ordered niobium-silica materials: Versatile catalysts for the selective epoxidation of various unsaturated fine chemicals
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Two kinds of niobium(V)-silica catalysts for the selective epoxidation were synthesised by post-synthesis modification of non-ordered mesoporous silica supports, starting from niobocene dichloride via solvent-less organometallic precursor dry impregnation
- Tiozzo, Cristina,Bisio, Chiara,Carniato, Fabio,Guidotti, Matteo
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- Dioxomolybdenum(VI) complexes with naphtholate-oxazoline ligands in catalytic epoxidation of olefins
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Synthesis, characterization and catalytic epoxidation experiments of two new dioxomolybdenum(VI) complexes [MoO2(L)2] (3a-b) equipped with O,N-bidentate naphtholate-oxazoline ligands L = 2a-b are described. Ligands 2a-b (2a = 2-(4,5-dihydrooxazol-2-yl)naphthalen-1-ol, 2b = 2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)naphthalen-1-ol) were obtained via a two-step synthesis starting from 1-hydroxy-naphthoic acid. Complexes 3a-b were synthesized starting from [MoO2(acac)2] and obtained in good yields as air and moisture stable solids. The molecular structure of both complexes 3a-b were determined by single crystal X-ray diffraction analysis, showing the expected octahedral coordination of the Mo center by two bidentate ligands of 2a or 2b and two terminal oxo ligands. Interestingly, for complex 3b two different coordination isomers with regards to the orientation of the bidentate ligands (N,N-trans 3b and N,N-cis 3b'), were obtained in the solid state. Both complexes 3a-b show high catalytic activities and selectivities in the epoxidation of various terminal and internal olefins at low catalyst loadings of 0.05 mol% with tert-butylhydroperoxide. With cyclooctene TON of 5000 could be reached, for styrene selectivities of >90% were achieved.
- Traar, Pedro,Schachner, J?rg A.,Stanje, Bernhard,Belaj, Ferdinand,M?sch-Zanetti, Nadia C.
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- Syntheses of chiral 1,8-cineole metabolites and determination of their enantiomeric composition in human urine after ingestion of 1,8-cineole- containing capsules
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The chiral metabolites in human urine were investigated after ingestion of a 1,8-cineole (eucalyptol)-containing enterocoated capsule (Soledum). For identification of the various enantiomers the enantiomerically pure (-/+)-α2-hydroxy-1,8- cineole, (-/+)-β2-hydroxy-1,8-cineole, (-/+)-9-hydroxy-1,8-cineole, and (-/+)-2-oxo-1,8-cineole were prepared. To achievethis aim, after acetylation of the synthesized racemic 2-and 9-hydroxy-1,8-cineoles, pig liver esterase- or yeast-mediated hydrolysis provided the (-)-alcohols with their antipodal(+)-acetates with enantiomeric excess of 33-100 %. Dess-Martin periodinane oxidation of the alcohol (+)-α2-hydroxy-1,8-cineole, obtained by hydrolysis of the resolved acetate, provided the corresponding (+)-2-oxo-1,8-cineole, meanwhile the oxidation of (-)-α2-hydroxy-1,8-cineole gave (-)-2-oxo-1,8-cineole. Using these standards seven metabolites (+/-)-α2-hydroxy-1,8-cineole, (+/-)-β2-hydroxy-1,8-cineole, (+/-)-α3-hydroxycineole,(+/-)-3-oxo-1, 8-cineole, 4-hydroxy-1,8-cineole, 7-hydroxy-1,8-cineole, and (+/-)-9-hydroxy-1,8-cineole, all liberated from their glucuronides, were identified in urine by GCMS on a chiral stationary phase after consumption of 10 mg of 1,8-cineole. Metabolite screening using 2H3-1,8- cineol as the internal standard revealed (+/-)-α2-hydroxy-1,8-cineole as the predominant metabolite followed by (+/-)-9-hydroxy-1,8-cineole. Furthermore, the results showed that one enantiomer is always formed preferentially.
- Schaffarczyk, Monika,Balaban, Teodor Silviu,Rychlik, Michael,Buettner, Andrea
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- Dimeric μ-oxo bridged molybdenum(vi) dioxo complexes as catalysts in the epoxidation of internal and terminal alkenes
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The preparation of the tridentate phenol based amine ligands HL1-HL4 is achieved via a convenient one-pot synthesis by reductive amination in quantitative yield in an autoclave under 7 bar H2 gas. Reaction of [MoO2(acac)2] and the corresponding ligand HLX (X = 1, 2 and 4) in methanol-H2O results in the formation of orange to red dimeric μ-oxo bridged [{MoO2(LX)}2(μ-O)] (X = 1, 2 and 4) complexes 1-3 in high yield and high purity. Complexes 1-3 are stable towards air and water. Both ligands coordinate via the phenolic O atom, the amine N atom and the third donor atom in the side chain (OMe for 1 and NMe 2 for 2 and 3) in a fac mode to the metal center. The molybdenum atoms are linked by a bridging μ-oxo moiety to each other as confirmed by X-ray diffraction analyses of complexes 2 and 3. All complexes have been tested in the epoxidation of several internal and terminal alkenes using TBHP as an oxidant. Depending on the nature of the substrate, the epoxides are obtained in moderate to good yields and high selectivities. In the epoxidation of cyclooctene a TOF = 467 h-1 with complex 1 has been observed, significantly higher compared to other dimeric complexes reported in the literature. In the more challenging epoxidation of styrene, complexes 1 and 2 have proven to be highly selective as only the formation of styrene oxide is observed. The OMe based complex 1 has also proven to be more active than the NMe2 based counterparts 2 and 3. The basic conditions induced by the NMe2 groups in complexes 2 and 3 lower their catalytic activity.
- Judmaier, Martina E.,Sala, Chris H.,Belaj, Ferdinand,Volpe, Manuel,Moesch-Zanetti, Nadia C.
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p. 2139 - 2149
(2013/10/08)
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- METHOD FOR MANUFACTURING AN EPOXY COMPOUND AND METHOD FOR EPOXIDIZING A CARBON-CARBON DOUBLE BOND
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The present invention provides a method for producing an epoxy compound, comprising oxidizing a carbon-carbon double bond of an organic compound by hydrogen peroxide in the presence of a neutral inorganic salt and a mixed catalyst of a tungsten compound (a), at least one phosphorus compound selected from the group consisting of phosphoric acids, phosphonic acids, and salts thereof (b) and a surfactant (c), and an epoxidizing method comprising oxidizing a carbon-carbon double bond by hydrogen peroxide in the presence of the catalyst and the neutral inorganic salt.
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Page/Page column 12
(2012/05/07)
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- Unique salt effect on highly selective synthesis of acid-labile terpene and styrene oxides with a tungsten/Hcatalytic system under acidic aqueous conditions
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Acid-labile epoxides such as terpene and styrene oxides are effectively synthesized in high yields with good selectivities using tungsten-catalyzed hydrogen peroxide epoxidation in the presence of NaO The salt effect is thought to originate with the addition of a saturated amount of NaOto aqueous H this addition strongly inhibited the undesired hydrolysis of the acid-labile epoxy products, despite the biphasic conditions of substrate as oil phase and Has acidic aqueous phase.
- Hachiya, Houjin,Kon, Yoshihiro,Ono, Yutaka,Takumi, Kiyoshi,Sasagawa, Naoki,Ezaki, Yoichiro,Sato, Kazuhiko
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experimental part
p. 1672 - 1678
(2012/07/16)
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- Molybdenum(VI) dioxo complexes employing schiff base ligands with an intramolecular donor for highly selective olefin epoxidation
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Reaction of [MoO2(η2-tBu2pz) 2] with Schiff base ligands HLX (X = 1-5) gave molybdenum(VI) dioxo complexes of the type cis-[MoO2(L X)2] as yellow to light brown solids in moderate to good yields. All ligands coordinate via its phenolic O atom and the imine N atom in a bidentate manner to the metal center. The third donor atom (R2 = OMe or NMe2) in the side chain in complexes 1-4 is not involved in coordination and remains pendant. This was confirmed by X-ray diffraction analyses of complexes 1 and 3. Complexes 1, 3, and 5 exist as a mixture of two isomers in solution, whereas complexes 2 and 4 with sterically less demanding substituents on the aromatics only show one isomer in solution. All complexes are active catalysts in the epoxidation of various internal and terminal alkenes, and epoxides in moderate to good yields with high selectivities are obtained. In the challenging epoxidation of styrene, complexes 1 and 2 prove to be very active and selective. The selectivity seems to be influenced by the pendant donor arm, as complex 5 without additional donor in the side chain is less selective. Experiments prove that the addition of n-butyl methyl ether as intermolecular donor per se has no influence on the selectivity. The basic conditions induced by the NMe2 groups in complexes 3 and 4 lead to lower activity.
- Judmaier, Martina E.,Holzer, Christof,Volpe, Manuel,Moesch-Zanetti, Nadia C.
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p. 9956 - 9966
(2012/10/29)
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- An effective synthesis of acid-sensitive epoxides via oxidation of terpenes and styrenes using hydrogen peroxide under organic solvent-free conditions
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An efficient epoxidation process for various terpenes and styrenes using a hydrogen peroxide-tungsten catalytic system with organic solvent-and halide-free conditions was developed. In the presence of the catalytic system, Na 2WO4, PhP(O)(OH)2, and [Me(n-C 8H17)3N]HSO4, and under weak acidic conditions, hydrogen peroxide successfully epoxidized -pinene to -pinene oxide in 95% selectivity at 91% conversion, while the previously published conditions utilizing NH2CH2P(O)(OH)2 as a promoter provided no epoxide. Georg Thieme Verlag Stuttgart.
- Kon, Yoshihiro,Hachiya, Houjin,Ono, Yutaka,Matsumoto, Tomohiro,Sato, Kazuhiko
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experimental part
p. 1092 - 1098
(2011/05/14)
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- Unique salt effect on the high yield synthesis of acid-labile terpene oxides using hydrogen peroxide under acidic aqueous conditions
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Acid-labile epoxides such as -pinene oxide are (effectively) synthesized in high yield from the epoxidation of terpenes with aqueous H2O 2 catalyzed by Na2WO4, [Me(n-C 8H17)3N]HSO4, and PhP(O)(OH) 2 in the presence of Na2SO4 as an auxiliary additive under organic solvent-free conditions at ambient temperature. Origin of the salt effect is considered that the addition of a saturated amount of Na2SO4 to aqueous H2O2 strongly inhibited the undesired hydrolysis of the acid-labile epoxide products, despite the highly acidic reaction conditions. Georg Thieme Verlag Stuttgart · New York.
- Hachiya, Houjin,Kon, Yoshihiro,Ono, Yutaka,Takumi, Kiyoshi,Sasagawa, Naoki,Ezaki, Yoichiro,Sato, Kazuhiko
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scheme or table
p. 2819 - 2822
(2012/01/02)
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- Epoxidation of olefins by β-bromoalkoxydimethylsulfonium ylides
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Olefins can be converted to their respective epoxides in a one-pot procedure by dissolving the olefin in anhydrous DMSO, adding NBS to the reaction mixture to generate a β-bromoalkoxydimethylsulfonium ylide, and then adding DBU to the reaction mixture. A large variety of alkenes were successfully epoxi-dized with yields largely dependent on the structure of the alkene. Most importantly, the facial selectivity of this one-pot process is the opposite of that observed when using traditional epoxidizing reagents. Electron-poor alkenes are not epoxidized under these conditions.
- Majetich, George,Shimkus, Joel,Li, Yang
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supporting information; experimental part
p. 6830 - 6834
(2011/03/18)
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- An effective procedure for the synthesis of acid-sensitive epoxides: Use of 1-methylimidazole as the additive on methyltrioxorhenium-catalyzed epoxidation of alkenes with hydrogen peroxide
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An effective method for suppression of ring opening and rearrangement of acid-sensitive epoxides during methyltrioxorhenium(MTO)-catalyzed epoxidation of alkenes with H2O2 by using 1-methylimidazole as a co-additive has been found. The combined use of 3-methylpyrazole and 1-methylimidazole as the additives has been found to be an effective procedure that affords excellent yields of acid-sensitive epoxides for MTO-catalyzed epoxidation.
- Yamazaki, Shigekazu
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experimental part
p. 2377 - 2385
(2010/07/06)
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- An effective catalytic epoxidation of terpenes with hydrogen peroxide under organic solvent-free conditions
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A catalytic system that operates well for the epoxidation of α-pinene, a very challenging substrate, at near-neutral pH and ambient temperature without organic solvent was developed. With hydrogen peroxide as a terminal oxidant, combination of Na2WO4, PhP(O)(OH) 2, and [Me(n-C8H17)3N]HSO 4 successfully catalyzed the epoxidation of α-pinene to give α-pinene oxide in 95% selectivity at 91% conversion, while the previously published conditions that use NH2CH2P(O)(OH)2 as a promoter provide no epoxide. The method is also well applicable to the epoxidation of the other acidsensitive terpenes. Georg Thieme Verlag Stuttgart.
- Kon, Yoshihiro,Ono, Yutaka,Matsumoto, Tomohiro,Sato, Kazuhiko
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scheme or table
p. 1095 - 1098
(2009/09/25)
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- Stereoselective Cyclization assisted by the Selenyl Group. Biogenetic-type Synthesis in the p-Menthane Series
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Acid-catalysed cyclization of the β-hydroxyselenide (3), derived from linalyl acetate (1), afforded the trans-p-menthanes (4) and (5), the structures of which were confirmed by their transformation into (6), (11), (8), and (13), and alternative syntheses of these compounds.The structure determination of some products obtained by the reaction of limonene and α-terpineol epoxides with phenylselenium anion was also carried out.
- Kametani, Tetsuji,Kurobe, Hiroshi,Nemoto, Hideo
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p. 756 - 760
(2007/10/02)
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