- Iron-Catalyzed Prins-Peterson Reaction for the Direct Synthesis of δ4-2,7-Disubstituted Oxepenes
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A direct iron(III)-catalyzed Prins-Peterson reaction involving α-substituted γ-triphenylsilyl bis-homoallylic alcohols and aldehydes is described. Thus, cis-4-2,7-disubstituted oxepenes were synthesized in a diastereoselective reaction using su
- Sinka, Victoria,Padrón, Juan I.,Cruz, Daniel A.,Martín, Víctor S.
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- Catalytic oxygen atom transfer promoted by tethered Mo(VI) dioxido complexes onto silica-coated magnetic nanoparticles
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The preparation of three novel active and stable magnetic nanocatalysts for the selective liquid-phase oxidation of several olefins, has been reported. The heterogeneous systems are based on the coordination of cis-MoO2 moiety onto three different SCMNP@Si-(L1-L3) magnetically active supports, functionalized with silylated acylpyrazolonate ligands L1, L2 and L3. Nanocatalysts thoroughly characterized by ATR-IR spectroscopy, TGA and ICP-MS analyses, showed excellent catalytic performances in the oxidation of conjugated or unconjugated olefins either in organic or in aqueous solvents. The good magnetic properties of these catalytic systems allow their easy recyclability, from the reaction mixture, and reuse over five runs without significant decrease in the activity, either in organic or water solvent, demonstrating their versatility and robustness.
- Colaiezzi, Roberta,Crucianelli, Marcello,Di Giuseppe, Andrea,Ferella, Francesco,Lazzarini, Andrea,Paolucci, Valentina
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- Direct synthesis of benzoxazinones via Cp*Co(III)-catalyzed C–H activation and annulation of sulfoxonium ylides with dioxazolones
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A highly novel and direct synthesis of benzoxazinones was developed via Cp*Co(III)-catalyzed C–H activation and [3 + 3] annulation between sulfoxonium ylides and dioxazolones. The reaction is conducted under base-free conditions and tolerates various functional groups. Starting from diverse readily available sulfoxonium ylides and dioxazolones, a variety of benzoxazinones could be synthesized in one step in 32%-75% yields.
- Yu, Yongqi,Xia, Zhen,Wu, Qianlong,Liu, Da,Yu, Lin,Xiao, Yuanjiu,Tan, Ze,Deng, Wei,Zhu, Gangguo
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supporting information
p. 1263 - 1266
(2020/10/08)
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- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
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The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
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supporting information
p. 8013 - 8017
(2021/10/25)
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- A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles
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A new heterogeneous catalytic system consisting of cobalt nanoparticles (CoNPs) supported on MgO and tert-butyl hydroperoxide (TBHP) as oxidant is presented. This CoNPs@MgO/t-BuOOH catalytic combination allowed the epoxidation of a variety of olefins with good to excellent yield and high selectivity. The catalyst preparation is simple and straightforward from commercially available starting materials and it could be recovered and reused maintaining its unaltered high activity.
- Rossi-Fernández, Lucía,Dorn, Viviana,Radivoy, Gabriel
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supporting information
p. 519 - 526
(2021/03/31)
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- Dendrimer crown-ether tethered multi-wall carbon nanotubes support methyltrioxorhenium in the selective oxidation of olefins to epoxides
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Benzo-15-crown-5 ether supported on multi-wall carbon nanotubes (MWCNTs) by tethered poly(amidoamine) (PAMAM) dendrimers efficiently coordinated methyltrioxorhenium in the selective oxidation of olefins to epoxides. Environmentally friendly hydrogen peroxide was used as a primary oxidant. Up to first and second generation dendrimer aggregates were prepared by applying a divergent PAMAM methodology. FT-IR, XRD and ICP-MS analyses confirmed the effective coordination of methyltrioxorhenium by the benzo-15-crown-5 ether moiety after immobilization on MWCNTs. The novel catalysts converted olefins to the corresponding epoxides in high yield without the use of Lewis base additives, or anhydrous hydrogen peroxide, the catalyst being stable for more than six oxidative runs. In the absence of the PAMAM structure, the synthesis of diols largely prevailed.
- Bizzarri, Bruno Mattia,Botta, Lorenzo,Crucianelli, Marcello,Fanelli, Angelica,Ferella, Francesco,Gontrani, Lorenzo,Sadun, Claudia,Saladino, Raffaele
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p. 17185 - 17194
(2020/05/18)
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- Nickel-catalyzed deoxygenation of oxiranes: Conversion of epoxides to alkenes
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Deoxygenation of epoxides takes place under the catalysis of nickel in the presence of diethylzinc as a deoxygenation agent to yield alkenes. Epoxides with a wide variety of substitution patterns are deoxygenated in this catalytic system to give terminal, 1,1-disubstituted, 1,2-disubstituted, trisubstituted, and tetrasubstituted alkenes in high yields. Reactions of 1,2-disubstituted epoxides we examined proceeded in an E-stereoselective manner. High compatibility with other functional groups through this transformation was also observed.
- Mori, Takamichi,Takeuchi, Yoshihito,Hojo, Makoto
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supporting information
(2020/01/24)
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- A highly efficient heterogeneous catalyst of bimetal-organic frameworks for the epoxidation of olefin with H2O2
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A series of bimetel organic framework MnxCu1?x-MOF were prepared. The MOFs was characterized and analyzed by powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmissio
- Huang, Hong,Lv, Jing,Meng, Xiang-Guang,Wang, Fei,Wu, Yan-Yan,Yu, Wen-Wang
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- One-pot synthesis of oxazolidinones and five-membered cyclic carbonates from epoxides and chlorosulfonyl isocyanate: Theoretical evidence for an asynchronous concerted pathway
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The one-pot reaction of chlorosulfonyl isocyanate (CSI) with epoxides having phenyl, benzyl and fused cyclic alkyl groups in different solvents under mild reaction conditions without additives and catalysts was studied. Oxazolidinones and five-membered cyclic carbonates were obtained in ratios close to 1:1 in the cyclization reactions. The best yields of these compounds were obtained in dichloromethane (DCM). Together with 16 known compounds, two novel oxazolidinone derivatives and two novel cyclic carbonates were synthesized with an efficient and straightforward method. Compared to the existing methods, the synthetic approach presented here provides the following distinct advantageous: being a one-pot reaction with metal-free reagent, having shorter reaction times, good yields and a very simple purification method. Moreover, using the density functional theory (DFT) method at the M06-2X/6-31+G(d,p) level of theory the mechanism of the cycloaddition reactions has been elucidated. The further investigation of the potential energy surfaces associated with two possible channels leading to oxazolidinones and five-membered cyclic carbonates disclosed that the cycloaddition reaction proceeds via an asynchronous concerted mechanism in gas phase and in DCM.
- Demir, Esra,Sari, Ozlem,?etinkaya, Yasin,Atmaca, Ufuk,Erdem, Safiye Sa?,?elik, Murat
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supporting information
p. 1805 - 1819
(2020/11/07)
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- Rh(III)-Catalyzed sequential: Ortho-C-H oxidative arylation/cyclization of sulfoxonium ylides with quinones toward 2-hydroxy-dibenzo [b,d] pyran-6-ones
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A rhodium(iii)-catalyzed ortho-C-H functionalization of sulfoxonium ylides followed by intramolecular annulation reactions with quinones was described, where the carbonyl in sulfoxonium ylides served as a chelation group. This protocol leads to the effici
- Cheng, Jiang,Dong, Yaqun,Sun, Song,Yu, Jin-Tao
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supporting information
p. 6688 - 6691
(2020/07/03)
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- Carbonylative C?C Bond Activation of Electron-Poor Cyclopropanes: Rhodium-Catalyzed (3+1+2) Cycloadditions of Cyclopropylamides
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Rh-catalyzed carbonylative C?C bond activation of cyclopropylamides generates configurationally stable rhodacyclopentanones that engage tethered alkenes in (3+1+2) cycloadditions. These studies provide the first examples of multicomponent cycloadditions t
- Dalling, Andrew G.,Yamauchi, Takayuki,McCreanor, Niall G.,Cox, Lydia,Bower, John F.
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supporting information
p. 221 - 225
(2018/12/11)
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- An alternative synthesis of the CNS stimulant Prolintane
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An alternative synthesis of prolintane, a CNS stimulant, is reported using commercially available allylbenzene in good overall yield (32.3%). The key transformations include epoxidation, Grignard reaction, Mitsunobu and reduction protocols.
- Mujahid,Korpe,Deshmukh,Bhadange,Muthukrishnan
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- Ruthenium(II)-Catalyzed Homocoupling of Weakly Coordinating Sulfoxonium Ylides via C?H Activation/Annulations: Synthesis of Functionalized Isocoumarins
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Homocoupling of weakly coordinating sulfoxonium ylides was accomplished via ruthenium (II) catalyzed C?H activation process. This strategy provides a convenient, efficient and step-economic method to access 3-substituted isocoumarins with good functional
- Zhou, Ming-Dong,Peng, Zhen,Wang, He,Wang, Zhao-Hui,Hao, Da-Jin,Li, Lei
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supporting information
p. 5191 - 5197
(2019/11/13)
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- Synthesis of Vicinal Dichlorides via Activation of Aliphatic Terminal Epoxides with Triphosgene and Pyridine
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Herein we report a novel synthetic reaction to convert unactivated terminal aliphatic epoxide to alkyl vicinal dichloride based on triphosgene-pyridine activation. Our methodology is operationally simple and readily tolerated by a broad of scope of substrates as well as protecting groups. Furthermore, these mild conditions generally yield clean reaction mixtures that are free of byproducts upon aqueous workup.
- Cleveland, Alexander H.,Fronczek, Frank R.,Kartika, Rendy
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p. 3367 - 3377
(2018/03/26)
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- Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds
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Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular SN2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.
- Li, Siqi,Chen, Xingpeng,Xu, Jiaxi
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supporting information
p. 1613 - 1620
(2018/03/07)
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- Synthesis of Alkenyl Boronates from Epoxides with Di-[B(pin)]-methane via Pd-Catalyzed Dehydroboration
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A practical and broadly applicable catalytic method for the synthesis of (E)-alkenylborons is presented. Reactions are promoted by [Pd(Cl)(η3-C3H5)]2 and proceed by the dehydroboration of cyclic borates. Through
- Murray, Stephanie A.,Luc, Eugenia C. M.,Meek, Simon J.
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supporting information
p. 469 - 472
(2018/01/28)
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- Efficient epoxidation reaction of terminal olefins with hydrogen peroxide catalyzed by an iron (II) complex
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A highly active iron (II) complex that catalyzed epoxidation of terminal olefins with hydrogen peroxide was described. The catalytic system displayed excellent catalytic ability for the selective oxidation of terminal olefins to epoxides with high selecti
- Li, Lu,Song, Hong-Jin,Meng, Xiang-Guang,Yang, Ren-Qiang,Zhang, Ni
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supporting information
p. 2436 - 2439
(2018/05/24)
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- Facile synthesis of thietanes via ring expansion of thiiranes
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Thietanes are pharmaceutically important cores of some biological compounds and intermediates of organic synthesis. Various thietanes were prepared from thiiranes via ring expansion through a reaction with trimethyloxosulfonium iodide in the presence of sodium hydride. The reaction process is a nucleophilic ring-opening reaction of thiiranes with dimethyloxosulfonium methylide, generated from trimethyloxosulfonium iodide and sodium hydride, and subsequent intramolecular displacement (cyclization) of thiolates to the dimethyloxosulfonium moiety. The current method provides a new strategy for efficient preparation of thietanes from readily available thiiranes.
- Dong, Jun,Xu, Jiaxi
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p. 836 - 844
(2017/02/05)
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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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- Recyclable Pd supported catalysts with low loading for efficient epoxidation of olefins at ambient conditions
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Epoxides are a kind of useful synthetic intermediates. This work reports that activated carbon-supported Pd nanoparticles (Pd/C) efficiently catalyzed cyclohexene epoxidation in the presence of molecular oxygen and isobutyraldehyde with 91.5% conversion,
- He, Xiaohui,Chen, Long,Zhou, Xiantai,Ji, Hongbing
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- Modular Access to Substituted Azocanes via a Rhodium-Catalyzed Cycloaddition-Fragmentation Strategy
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A short entry to substituted azocanes by a Rh-catalyzed cycloaddition-fragmentation process is described. Specifically, exposure of diverse N-cyclopropylacrylamides to phosphine-ligated cationic Rh(I) catalyst systems under a CO atmosphere enables the directed generation of rhodacyclopentanone intermediates. Subsequent insertion of the alkene component is followed by fragmentation to give the heterocyclic target. Stereochemical studies show, for the first time, that alkene insertion into rhodacyclopentanones can be reversible.
- Shaw, Megan H.,Croft, Rosemary A.,Whittingham, William G.,Bower, John F.
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supporting information
p. 8054 - 8057
(2015/07/15)
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- Efficient and convenient epoxidation of alkenes to epoxides with H2O2 catalyzed by Co(OAc)2 in ionic liquid [C12py][PF6]
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A simple, efficient, and eco-friendly procedure for the epoxidation of alkenes to epoxides with H2O2 catalyzed by Co(OAc)2 in ionic liquid [C12py][PF6] has been developed. The reactions were carried out with alkene, Co(OAc)2 (0.1 mmol), [C12py][PF6] (10 mL), and H2O2 (30 %, 11 mmol) at room temperature for 2-6 h. This atom-economical protocol affords the target products in good to high yields (88-98 %). The products can be separated by a simple extraction with organic solvent, and the catalytic system can be recycled and reused without loss of catalytic activity. Graphical abstract: A simple, efficient, and eco-friendly procedure for the epoxidation of alkenes to epoxides with H2O2 catalyzed by Co(OAc)2 in ionic liquid [C12py][PF6] has been developed.[Figure not available: see fulltext.]
- Hu, Yu-Lin,Liu, Yi-Wen,Li, De-Jiang
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p. 2179 - 2184
(2015/10/19)
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- Silica microspheres containing high density surface hydroxyl groups as efficient epoxidation catalysts
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Uniformly sized silica microspheres were synthesized by a hydrolysis-condensation method. The obtained material was etched with a mild aqueous potassium hydroxide solution for different periods of time to break their Si-O-Si bonds and increases the density of hydroxyl groups on their surfaces. The resulting materials were then used as transition metal-free catalysts for oxidation of olefins in the presence of hydrogen peroxide as a green oxidant. The materials were thoroughly characterized using various physicochemical techniques. These highly populated hydroxyl groups on the surface of silica microspheres were proven to be responsible for excellent conversion (up to 93%) and epoxide selectivity (up to 100%) for various olefins. Quantum mechanical calculations also corroborate the experimental findings. Furthermore, both experimental and theoretical studies show that tertiary silanols were present at the active sites of the catalyst surface and were responsible for olefin epoxidation.
- Chandra, Prakash,Doke, Dhananjay S.,Umbarkar, Shubhangi B.,Vanka, Kumar,Biradar, Ankush V.
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p. 21125 - 21131
(2015/03/30)
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- Optimized benzaldehyde production over a new Co-ZSM-11 catalyst: Reaction parameters effects and kinetics
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An efficient Co-ZSM-11 catalyst has been synthesized for benzaldehyde production by the selective styrene oxidation. Reaction parameters such as catalyst mass, reaction temperature, molar ratio styrene/hydrogen peroxide and stirring speed were optimized, by performing the styrene oxidation reaction in a stirred batch system with fine particles of Co-ZSM-11 in suspension under microwave heating. A kinetic study was done by using the initial rate method and the Arrhenius parameters were estimated. This catalyst presents a higher reaction rate about 30% with respect of those found in literature and a higher selectivity towards benzaldehyde about 80% at optimal conditions.
- Azzolina Jury, Federico,Polaert, Isabelle,Pierella, Liliana B.,Estel, Lionel
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- Cyclohexanones by Rh-mediated intramolecular C-H insertion
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Some long chain α-aryl α-diazo ketones under Rh catalysis cyclize efficiently to the corresponding cyclohexanones. This is in marked contrast to the cyclizations of α-diazo β-ketoesters, which consistently deliver cyclopentanone products.
- Taber, Douglass F.,Paquette, Craig M.,Gu, Peiming,Tian, Weiwei
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p. 9772 - 9780
(2013/10/22)
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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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p. 13160 - 13166
(2013/12/04)
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- Synthesis, structural characterization, encapsulation in zeolite y and catalytic activity of an oxidovanadium(V) complex with a tribasic pentadentate ligand
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Reaction of [VIVO(acac)2] with H3hap-dahp (I: Schiff base derived from 2-hydroxyacetophenone and 1,3-diamino-2- hydroxypropane) in methanol under aerobic conditions resulted in the formation of the complex [VVO(hap-dahp)] (1). Treatment of I with vanadium(IV) exchanged zeolite Y followed by aerial oxidation gave the encapsulated oxidovanadium(V) complex [VVO(hap-dahp)]-Y (2) in the nanocavity of zeolite Y. Elemental analysis, spectroscopic (IR, electronic, 1H and 51V NMR) studies, scanning electron micrographs and X-ray diffraction patterns have been used to characterize these complexes, which have a distorted octahedral structure, confirming the tribasic O3N2 binding mode of the ligand. The encapsulated complex [VVO(hap-dahp)]- Y (2) catalyzes the oxidation of styrene, methyl phenyl sulfide and diphenyl sulfide using H2O2 as an oxidant in good yield (82%, 98% and 81%, respectively). Styrene, under optimized reaction conditions, gave five reaction products, namely styrene oxide, benzaldehyde, 1-phenylethane-1,2-diol, benzoic acid and phenylacetaldehyde, while the organic sulfides gave the corresponding sulfoxides as the major product. The neat complex [V VO(hap-dahp)] (1) also exhibits good catalytic activity for these substrates. The encapsulated complex showed a good recycling ability.
- Maurya, Mannar R.,Bisht, Manisha,Chaudhary, Nikita,Avecilla, Fernando,Kumar, Umesh,Hsu, Hua-Fen
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p. 180 - 188
(2013/07/31)
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- Unusual reactivity of dimethylsulfoxonium methylide with esters
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The dimethylsulfoxonium methylide was treated with esters under mild conditions to rapidly afford the corresponding carboxylic acids at room temperature. Moreover, by performing the procedure on enantiopure substrates, it was demonstrated that the reaction occurs without racemization. 18O-labeled reagents showed that the reaction does not proceed through an ester hydrolysis mechanism. The reactions are characterized by an unusual reactivity of the dimethylsulfoxonium methylide. This methodology is general and can be considered a valid alternate route for ester cleavage when a substrate is sensitive to hydrolysis conditions.
- Leggio, Antonella,De Marco, Rosaria,Perri, Francesca,Spinella, Mariagiovanna,Liguori, Angelo
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experimental part
p. 114 - 118
(2012/02/14)
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- Synthesis of propargylic and allenic carbamates via the C-H amination of alkynes
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Propargylic amines are important intermediates for the synthesis of nitrogen-containing heterocycles. The insertion of a nitrene into a propargylic C-H bond has not been explored, despite the attention directed toward the Rh-catalyzed amination of other t
- Grigg, R. David,Rigoli, Jared W.,Pearce, Simon D.,Schomaker, Jennifer M.
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supporting information; experimental part
p. 280 - 283
(2012/02/16)
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- 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)
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- Absolute configuration for 1, n-glycols: A nonempirical approach to long-range stereochemical determination
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The absolute configurations of 1,n-glycols (n = 2-12, 16) bearing two chiral centers were rapidly determined via exciton-coupled circular dichroism (ECCD) using a tris(pentafluorophenyl)porphyrin (TPFP porphyrin) tweezer system in a nonempirical fashion devoid of chemical derivatization. A unique "side-on" approach of the porphyrin tweezer relative to the diol guest molecule is suggested as the mode of complexation.
- Li, Xiaoyong,Burrell, Carmin E.,Staples, Richard J.,Borhan, Babak
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supporting information; experimental part
p. 9026 - 9029
(2012/07/13)
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- Epoxidation of olefins with a silica-supported peracid in supercritical carbon dioxide under flow conditions
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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)
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- A novel convergent method for the synthesis of α-acyl-γ- hydroxylactams and its application in the total synthesis of PI-090 and 091
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A novel convergent method for the synthesis of α-acyl-γ- hydroxylactams utilizing the aldol reaction of N-Boc-protected γ-methoxylactams was developed. As the first application of this method for the synthesis of biologically active natural products, the total synthesis of platelet aggregation inhibitors PI-090 and PI-091 were also investigated and successfully achieved.
- Uchiro, Hiromi,Shionozaki, Nobuhiro,Kobayakawa, Yu,Nakagawa, Hiroko,Makino, Kimiko
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scheme or table
p. 4765 - 4768
(2012/08/07)
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- Phosphotungstic acid supported on magnetic nanoparticles as an efficient reusable catalyst for epoxidation of alkenes
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A new magnetically separable catalyst consisting of phosphotungstic acid supported on imidazole functionalized silica coated cobalt ferrite nanoparticles was prepared. The synthesized catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). This immobilized phosphotungstic acid was shown to be an efficient heterogeneous catalyst for the epoxidation of various alkenes using tert-butylhydroperoxide (t-BuOOH) as oxidant. The catalyst is readily recovered by simple magnetic decantation and can be recycled several times with no significant loss of catalytic activity.
- Kooti,Afshari
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p. 3473 - 3478
(2012/11/07)
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- Synthesis of (R)-selegiline via hydrolytic kinetic resolution
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A short and enantioselective formal synthesis of (R)-selegiline has been achieved using Jacobsen's hydrolytic kinetic resolution (HKR) of phenyl propylene oxide.
- Kondekar, Nagendra B.,Kumar, Pradeep
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experimental part
p. 1301 - 1308
(2011/05/07)
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- SOLID PHASE REACTION SYSTEM FOR OXIDATION
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A solid phase reaction system for oxidation of an organic compound, having high industrial value in which an organic solvent exerting a reverse influence on earth environments is not necessary, reuse of a catalyst is possible, and high yield can be attained, comprising a mixture of a powdery dispersion medium and a powder of a solid catalyst for the above-described oxidation reaction, and the above-described organic compound and aqueous hydrogen peroxide,wherein the above-described organic compound, the above-described solid catalyst and the above-described aqueous hydrogen peroxide are dispersed in the above-described mixture so that they get into contact mutually.
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Page/Page column 6-7
(2010/05/13)
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- One-pot conversions of olefins to cyclic carbonates and secondary allylic and homoallylic amines to cyclic carbamates
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Sequential treatment of a 1,2-disubstituted olefin with m-CPBA, Br 3CCO2H, and DBU results in the one-pot, stereospecific conversion of the olefin to the corresponding disubstituted cyclic carbonate (1,3-dioxolan-2-one). The reaction proceeds via an initial epoxidation followed by SN2-type epoxide ring opening by Br3CCO2H and subsequent base-promoted carbonate formation upon elimination of bromoform. When a solution of a secondary allylic or homoallylic amine and Br 3CCO2H is sequentially treated with m-CPBA then DBU, the product of the reaction is a cyclic carbamate (1,3-oxazolidin-2-one or 1,3-oxazinan-2-one).
- Davies, Stephen G.,Fletcher, Ai M.,Kurosawa, Wataru,Lee, James A.,Poce, Giovanna,Roberts, Paul M.,Thomson, James E.,Williamson, David M.
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scheme or table
p. 7745 - 7756
(2011/01/05)
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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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- Rhodium nanoparticles supported on carbon nanofibers as an arene hydrogenation catalyst highly tolerant to a coexisting epoxido group
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Rhodium nanoparticles supported on a carbon nanofiber (Rh/CNF-T) show high catalytic activity toward arene hydrogenation under mild conditions in high turnover numbers without leaching the Rh species; the reaction is highly tolerant to epoxido groups, which often undergo ring-opening hydrogenation with conventional catalysts.
- Motoyama, Yukihiro,Takasaki, Mikihiro,Yoon, Seong-Ho,Mochida, Isao,Nagashima, Hideo
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supporting information; experimental part
p. 5042 - 5045
(2009/12/28)
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- Regioselectivity and diasteroselectivity in Pt(II)-mediated "green" catalytic epoxidation of terminal alkenes with hydrogen peroxide: Mechanistic insight into a peculiar substrate selectivity
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Recently developed electron-poor Pt(II) catalyst 1 with the "green" oxidant 35% hydrogen peroxide displays high activity and complete substrate selectivity in the epoxidation of terminal alkenes because of stringent steric and electronic requirements. In the presence of isolated dienes bearing terminal and internal double bonds, epoxidation is completely regioselective toward the production of terminal epoxides. Insight into the mechanism is gained by means of a reaction progress kinetic analysis approach that underlines the peculiar role of 1 in activating both the alkene and H 2O2 in the rate-determining step providing a rare example of nucleophilic oxidation of alkenes by H2O2.
- Colladon, Marco,Scarso, Alessandro,Sgarbossa, Paolo,Michelin, Rino A.,Strukul, Giorgio
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p. 7680 - 7689
(2008/02/05)
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- Alkene epoxidation with urea-hydrogen peroxide complex and PS-DVB supported phthalic anhydride
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A new PS-DVB supported phthalic anhydride and UHP (urea-hydrogen peroxide complex) have been used for metal-free alkene epoxidation reactions. The resin was prepared by MW mediated 'PEGylation' of Merrifield resin followed by esterification with trimellitic anhydride chloride. Epoxidation of several alkenes was carried out with this resin and UHP.
- Ghiron, Chiara,Nannetti, Lorenzo,Taddei, Maurizio
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p. 1643 - 1645
(2007/10/03)
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- Direct catalytic synthesis of enantiopure 5-substituted oxazolidinones from racemic terminal epoxides
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(Chemical Equation Presented) A venerable scaffold for asymmetric synthesis and drug development, chiral 5-substituted oxazolidinones are obtained in almost enantiomerically pure form (up to 99.9% ee) starting from racemic terminal epoxides. The salient features of this process include the very simple and convenient experimental protocol and the employment of a readily accessible catalyst and inexpensive, easily handled starting materials. An enantioconvergent approach for the total conversion of racemic epoxide into a single stereoisomeric oxazolidinone is also described.
- Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Locatelli, Manuela,Melchiorre, Paolo,Sambri, Letizia
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p. 1983 - 1985
(2007/10/03)
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- Design of a highly efficient catalyst for the oxaziridinium-mediated epoxidation of olefins by Oxone
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2,3,3-Trimethyl-7-nitro-3,4-dihydroisoquinolinium tetrafluoroborate is a highly efficient catalyst for the oxaziridinium-mediated epoxidation of a variety of olefins, including monosubstituted ones.
- Bohé, Luis,Kammoun, Majed
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p. 747 - 751
(2007/10/03)
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- Highly selective epoxidation of olefinic compounds over TS-1 and TS-2 redox molecular sieves using anhydrous urea-hydrogen peroxide as oxidizing agent
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Highly selective epoxidation of different olefinic compounds was carried out using urea-hydrogen peroxide adduct (UHP) as the oxidizing agent in the presence of TS-1 and TS-2 as redox catalysts. A considerable increase in the epoxide selectivity was observed for different unsaturated compounds, such as allylic (allyl alcohol, allyl chloride, allyl bromide, and methylallyl chloride), open-chain, and cyclic (1-hexene and cyclohexene) and aromatic (styrene and allylbenzene) olefinic compounds, when UHP and U + HP (urea and aqueous H2O2 added separately for the in situ formation of UHP) were used as oxidants instead of aqueous H2O2. The controlled release of anhydrous H2O2 from UHP is the main reason for enhanced epoxide selectivity. Direct spectroscopic evidences for the formation of different Ti-superoxo complexes by the solid-solid interaction between TS-1/TS-2 and urea-hydrogen peroxide adduct were obtained from the characteristic continuous absorption band in the UV-vis region (300-500 nm) and the anisotropic EPR spectra for the superoxide radical attached to Ti(IV) centers on TS-1 and TS-2.
- Laha,Kumar
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p. 339 - 344
(2007/10/03)
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- Urea-hydrogen peroxide/hexafluoro-2-propanol: An efficient system for a catalytic epoxidation reaction without a metal
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Hexafluoro-2-propanol (HFIP) exhibits a unique ability to release and activate H2O2 from the urea-hydrogen peroxide adduct (UHP). This UHP/HFIP system was investigated in epoxidation of olefins, using various fluoroketones as catalysts. With reactive olefins, no catalyst was required. With monosubstituted olefins, epoxides were obtained in high yields by using catalytic amounts (3-5%) of perfluorodecan-2-one. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Legros, Julien,Crousse, Benoit,Bonnet-Delpon, Daniele,Begue, Jean-Pierre
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p. 3290 - 3293
(2007/10/03)
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- Preparation of enantiomerically enriched flavor and fragrance components
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The present invention includes a process for enantioselective preparation of a non-racemic compound, which is either usable as a fragrance or flavor component or is convertible to a fragrance or flavor component by one or more additional reaction steps. T
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- Olefin epoxidation with bis(trimethylsilyl) peroxide catalyzed by inorganic oxorhenium derivatives. Controlled release of hydrogen peroxide
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The replacement of organometallic rhenium species (e.g., CH3ReO3) by less expensive and more readily available inorganic rhenium oxides (e.g., Re2O7, ReO3(OH), and ReO3) can be accomplished using bis(trimethylsilyl) peroxide (BTSP) as oxidant in place of aqueous H2O2. Using a catalytic amount of a proton source, controlled release of hydrogen peroxide helps preserve sensitive peroxorhenium species and enables catalytic turnover to take place. Systematic investigation of the oxorhenium catalyst precursors, substrate scope, and effects of various additives on olefin epoxidation with BTSP are reported in this contribution.
- Yudin,Chiang,Adolfsson,Copéret
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p. 4713 - 4718
(2007/10/03)
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- Activation of pig liver esterase in organic media with organic polymers. Application to the enantioselective acylation of racemic functionalized secondary alcohols
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Pig liver esterase (PLE) shows practically no activity in acylation of alcohols with vinylic esters in organic solvents. However, addition of methoxypoly(ethylene glycol) (MPEG), bovine serum albumin (BSA), TentaGelAmino resin (TGA), or aminomethyl polystyrene (AMPS) confers activity to PLE in acylation of alcohols with vinyl propionate in organic solvents of low water content. Polymer-activated PLE showed high enantioselectivities (E > 100) in the acylation of racemic 1-alkoxy-, 1-ethylsulfanyl-, and 1-fluoro-3-aryl-2-propanols as well as racemic 1-phenoxy-2-propanol and racemic 1-methoxy-2-phenoxy-2-propanol. The synthetic utility of polymer-activated PLE has been demonstrated by the gram-scale resolution of 1-methoxy-3-phenyl-2-propanol, 1-ethylsulfanyl-3-phenyl-2-propanol, 1-methoxy-3-p-methoxyphenyl-2-propanol, 1- fluoro-3-phenyl-2-propanol, and 1-methoxy-3-phenoxy-2-propanol. In PLE-catalyzed acylation of alcohols with vinyl propionate, acetaldehyde and propionic acids, both being detrimental to the enzyme, are formed as byproducts. In addition, the water content of the system, which is critical for the activity of pig liver esterase, is lowered because of a competing enzymatic hydrolysis of the acyl donor. The polymers TGA, BSA, and AMPS not only scavenge the aldehyde and the acid through imine formation and neutralization, respectively, but replenish at least in part also the water consumed in the competing hydrolysis of the acyl donor. A recovery of PLE together with the polymer was achieved without major loss of activity through their immobilization on a water-saturated polyaramide membrane, which occurs spontaneously in organic solvents.
- Gais,Jungen,Jadhav
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p. 3384 - 3396
(2007/10/03)
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- Epoxidation of olefins with peracid at low temperature with copper catalysis
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Treatment of a wide range of olefins with m-chloroperbenzoic acid (MCPBA) at low temperature in the presence of copper(I) and (II) catalysts in methylene chloride provides epoxides in good to excellent yields. (C) 2000 Elsevier Science Ltd.
- Andrus, Merritt B.,Poehlein, Benjamin W.
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p. 1013 - 1014
(2007/10/03)
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- Rhenium catalysed epoxidations with hydrogen peroxide: Tertiary arsines as effective cocatalysts
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Perrhenic acid in combination with tertiary arsines gives a versatile catalytic system for epoxidation of alkenes with hydrogen peroxide. The best results are obtained with diphenylmethylarsine. A wide range of alkenes could be epoxidised with aqueous hydrogen peroxide (60%) in 60-100% yields with substrate to catalyst ratios of up to 1000. The Royal Society of Chemistry 2000.
- Van Vliet, Michiel C.A.,Arenas, Isabel W.C.E.,Sheldon, Roger A.
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p. 377 - 380
(2007/10/03)
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