- Catalytic asymmetric epoxidation of 2-cyclopentenones
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The first highly efficient asymmetric epoxidation of 2-cyclopentenones has been developed. Using a newly designed and readily available Cinchona amine catalyst, 2-cyclopentenones are reacted with hydrogen peroxide to give the corresponding epoxycyclopentanones in high yields and excellent enantioselectivities. Copyright
- Lee, Anna,Reisinger, Corinna M.,List, Benjamin
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supporting information; experimental part
p. 1701 - 1706
(2012/07/30)
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- Amino-acid-mediated epoxidation of α,β-unsaturated ketones by hydrogen peroxide in aqueous media
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Amino acids, such as arginine and lysine, can be used as an efficient catalyst in the epoxidation of α,β-unsaturated ketones with aqueous hydrogen peroxide. Up to >99% conversion was obtained in the reaction toward 11 α,β-unsaturated ketones.
- Kim, Juhyun,Jung, Suhyun,Park, Seongsoon,Park, Sojung
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experimental part
p. 2866 - 2868
(2011/06/21)
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- Polymer-supported Oxone and tert-butyl hydroperoxide: new reagents for the epoxidation of α,β-unsaturated aldehydes and ketones
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Efficient, mild and selective epoxidation of α,β-unsaturated aldehydes and ketones was performed using polyvinylpyrrolidonesupported Oxone (Oxone/PVP) and ButOOH/PVP.
- Pourali, Ali Reza
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experimental part
p. 113 - 115
(2010/06/19)
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- An immobilized organocatalyst for cyanosilylation and epoxidation
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An immobilized organocatalyst has been synthesized by covalently anchoring an N-octyldihydroimidazolium hydroxide fragment onto SiO2 (denoted as 1-OH/SiO2). This catalyst exhibits high catalytic performance for the cyanosilylation of
- Yamaguchi, Kazuya,Imago, Toru,Ogasawara, Yoshiyuki,Kasai, Jun,Kotani, Miyuki,Mizuno, Noritaka
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p. 1516 - 1520
(2007/10/03)
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- Highly efficient epoxidation of α,β-unsaturated ketones by hydrogen peroxide with a base hydrotalcite catalyst prepared from metal oxides
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The base hydrotalcite, prepared from MgO and Al2O3, acted as a highly efficient catalyst for the epoxidation of α,β-unsaturated ketones using aqueous hydrogen peroxide as an oxidant. This heterogeneous epoxidation has the advantages of a high efficiency of H2O2 utilization without organic solvents, a simple workup procedure, and reusability of the hydrotalcite catalyst.
- Honma, Takayuki,Nakajo, Michiko,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 6229 - 6232
(2007/10/03)
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- Epoxidation of α,β-Unsaturated Ketones Using Hydrogen Peroxide in the Presence of Basic Hydrotalcite Catalysts
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The basic layered hydrotalcites have been used as catalysts for the epoxidation of α,β-unsaturated ketones in heterogeneous reaction media using hydrogen peroxide as an oxidant. A wide variety of α,β-unsaturated ketones were oxidized to the corresponding epoxyketones in excellent yields under mild reaction conditions. For example, 2-cyclohexen-1-one gave 2,3-epoxycyclohexanone in 91% yield at 40°C for 5 h with high efficiency in hydrogen peroxide. The catalytic activity of the hydrotalcites increased as the basicity of their surfaces increased. In the case of the epoxidation of less reactive substrates, adding a cationic surfactant such as n-dodecyltrimethylammonium bromide (DTMAB) to the above oxidation system accelerated the epoxidation reaction. These hydrotalcite catalysts were easily separated from the reaction mixture and were reusable.
- Yamaguchi, Kazuya,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
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p. 6897 - 6903
(2007/10/03)
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- Solid-acid catalysed rearrangement of cyclic α,β-epoxy ketones
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Various cyclic α,β-epoxy ketones rearranged to α-formyl ketones and/or vicdiones in the presence of catalytic amounts of zeolites and montmorillonite K10. This provides an excellent alternative to conventional homogeneous systems with respect to yields and workup. Differences in product distribution and type of products in the rearrangement of pulegone oxide could be reasonably explained by invoking different pathways for homogeneous and heterogeneous catalysts.
- Elings, Jacob A.,Lempers, Hans E. B.,Sheldon, Roger A.
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p. 1905 - 1911
(2007/10/03)
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- An easy deoxygenation of conjugated epoxides
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An easy and high yielding transformation of epoxyketones and phenyl substituted epoxides to trans olefins in a convergent diastereoselective process is reported. The method was applied to the selective C-25 hydroxy- functionalisation of 3-keio-Δ4-cholestan-3-one, a key intermediate for the synthesis of C-25 hydroxy vitamin D3. (C) 2000 Elsevier Science Ltd.
- Righi, Giuliana,Bovicelli, Paolo,Sperandio, Anna
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p. 1733 - 1737
(2007/10/03)
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- Highly chemo- and regioselective rearrangement of α,β-epoxy ketones to 1,3-dicarbonyl compounds in 5 mol dm-3 lithium perchlorate-diethyl ether medium
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Epoxides from α,β-unsaturated ketones undergo highly chemo- and regioselective rearrangement to 1,3-dicarbonyl compounds in 5 mol dm-3 lithium perchlorate-diethyl ether medium by a 1,2-migration of the carbonyl group at ambient conditions. The Royal Society of Chemistry 1999.
- Sankararaman,Ncsakumar
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p. 3173 - 3175
(2007/10/03)
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- KF adsorbed on alumina effectively promotes the epoxidation of electron deficient alkenes by anhydrous t-BuOOH
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KF adsorbed on alumina (KF-Al2O3) has been studied in detail for the epoxidation of electron deficient alkenes with anhydrous t-BuOOH. Aqueous base sensitive functional groups survive the reagent. Cyclopentenones are oxidized in decent to quantitative yields without showing any observable aldol products. α,β,γ,δ-Dienones are regioselectively oxidized at the α,β-position. Unlike aqueous alkaline H2O2, KF-Al2O3 is non-stereospecific and offers a mixture of cis and trans oxides from most acyclic enones. Except for the oxidation of α,β-unsaturated lactones and for the difference in reaction rates, the present reagent is, in general, similar to the t-BuOOH-DBU combination.
- Yadav,Kapoor
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p. 3659 - 3668
(2007/10/03)
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- Al2O3 Supported KF: An Efficient Mediator in the Epoxidation of Electron Deficient Alkenes with t-BOOH
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KF-Al2O3 is discovered to promote epoxidation of electron deficient alkenes.Functional groups that are labile to aqueous basic conditions survive.The steric demand for the reaction is higher than that for alkaline H2O2.
- Yadav, Veejendra K.,Kapoor, Kamal K.
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p. 9481 - 9484
(2007/10/02)
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- Formation of β-Hydroxyketones from α,β-Epoxyketones by Photoinduced Single Electron Transfer Reactions
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Irradiation of α,β-epoxyketones in acetonitrile at 254 nm in the presence of triethylamine afforded β-hydroxyketones in good to moderate yields. Key words: α,β-epoxyketones, β-hydroxyketones, radical, photochemistry.
- Cossy, J.,Bouzide, A.,Ibhi, S.,Aclinou, P.
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p. 7775 - 7782
(2007/10/02)
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- NOVEL TRANSFORMATIONS WITH BORONTRIFLUORIDE ETHERATE/IODIDE ION : FACILE CONVERSION OF 2-KETOOXIRANES AND 2-BROMO-2-ENONES TO THE α,β-UNSATURATED CARBONYL COMPOUNDS.
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Borontrifluoride etherate/iodide ion rapidly deoxygenates α-ketooxiranes, 3, to the corresponding α,β-unsaturated carbonyl compounds, 4, in near quantitative yields.In contrast, the reaction of 3 with borontrifluoride etherate/bromide ion, 2, yielded the corresponding 2-bromo-2-enone derivatives, 5, in excellent yields.The reagent 1, also dehalogenates a variety of 2-bromo-2-enones, 5, to the corresponding 2-en-1-one derivatives, 4, in high yields.
- Mandal, Arun K.,Mahajan, S. W.
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p. 2293 - 2300
(2007/10/02)
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- SYNTHESI OF 2-HYDROXY-3-METHYL-2-CYCLOPENTENONE FROM ISOPRENE
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Pyrolysis of the 1:1 isoprene-dichlorocarbene adduct and pyrolysis of the gem-dichlorocyclopentene gave 3-methyl-2-cyclopentenone which was further processed to the title compound.
- Ho, Tse-Lok,Lui, Shing-Hou
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p. 685 - 690
(2007/10/02)
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- Synthesis 2-alkyl cyclopentenolones
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2-Hydroxy-3-methylcyclopent-2-en-1-one was synthesized in a five-step synthesis starting from 2-methyl-1,3-butadiene. Novel intermediate steps include the hot tube isomerization of 1,1-dihalo-2-methyl-2-vinylcyclopropane to give 1-methyl-4,4-dihalocyclopent-1-ene, hydrolysis to 3-methyl-2-cyclopenten-1-one, epoxidation of the latter using a phase transfer catalyst, followed by catalyzed isomerization to produce 2-hydroxy-3-methylcyclopent-2-en-1-one in high overall yield.
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