- Highly Regioselective 5-endo-tet Cyclization of 3,4-Epoxy Amines into 3-Hydroxypyrrolidines Catalyzed by La(OTf)3
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Highly regioselective intramolecular aminolysis of 3,4-epoxy amines has been achieved. Key features of this reaction are (1) chemoselective activation of epoxides in the presence of unprotected aliphatic amines in the same molecules by a La(OTf)3 catalyst and (2) excellent regioselectivity for anti-Baldwin 5-endo-tet cyclization. This reaction affords 3-hydroxy-2-alkylpyrrolidines stereospecifically in high yields. DFT calculations revealed that the regioselectivity might be attributed to distortion energies of epoxy amine substrates. The use of this reaction was demonstrated by the first enantioselective synthesis of an antispasmodic agent prifinium bromide.
- Hoshino, Yoshihiko,Iwabuchi, Yoshiharu,Kuriyama, Yuse,Sasano, Yusuke,Uesugi, Shun-ichiro,Yamaichi, Aoto
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supporting information
p. 1961 - 1965
(2021/01/04)
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- New heptacoordinate tungsten(II) complexes with α-diimine ligands in the catalytic oxidation of multifunctional olefins
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New tungsten(II) and molybdenum(II) heptacoordinate complexes [MX2(CO)3(LY)] (MXLy: M = W, Mo; X = Br, I; LY = C5H4NCY = N(CH2)2CH3 with Y = H (L1), Me (L2), Ph (L3)) were synthesized and characterized by spectroscopic techniques and elemental analysis. The two tungsten complexes WXL1 (X = Br, I) were also structurally characterized by single crystal X-ray diffraction. The metal coordination environment is in both a distorted capped octahedron. The complexes with L1 and L2 ligands were grafted in MCM-41, after functionalization of the ligands with a Si(OEt)3 group. The new materials were characterized by elemental analysis, N2 adsorption isotherms, 29Si MAS and 13C MAS NMR. The tungsten(II) complexes and materials were the first examples of this type reported. All complexes and materials were tested as homogeneous and heterogeneous catalysts in the oxidation of multifunctional olefins (cis-hex-3-en-1-ol, trans-hex-3-en-1-ol, geraniol, S-limonene, and 1-octene), with tert-butyl hydroperoxide (TBHP) as oxidant. The molybdenum(II) catalyst precursors are in general very active, reaching 99% conversion and 100% selectivity in the epoxidation of trans-hex-3-en-1-ol. Their performance is comparable with that of the [Mo(η3-C3H5)X(CO)2(LY)] complexes, but it increases with immobilization. On the other hand, most of the W(II) complexes display an activity similar or inferior to that of the Mo(II) analogues and it decreases after they are supported in MCM-41. DFT calculations show that tungsten complexes and iodide ligands are more easily oxidized from M(II) to M(VI) than molybdenum ones, while the energies of relevant species in the catalytic cycle are very similar for all complexes, making the theoretical rationalization of experimental catalytic data difficult.
- Vasconcellos-Dias, Maria,Nunes, Carla D.,Félix, Vítor,Brand?o, Paula,Calhorda, Maria José
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- Borinic Acid-Catalyzed, Regioselective Ring Opening of 3,4-Epoxy Alcohols
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Diarylborinic acids (Ar2BOH) catalyze the C3-selective ring opening of 3,4-epoxy alcohols with aniline, dialkylamine and arenethiol nucleophiles. The regiochemical outcome is consistent with a catalytic tethering mechanism in which the borinic acid interacts with both the electrophile and the nucleophile. The rate acceleration resulting from this induced intramolecularity effect is sufficient to overcome steric biases that would otherwise favor C4-selective opening of the substituted epoxy alcohols.
- Wang, Grace,Garrett, Graham E.,Taylor, Mark S.
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supporting information
p. 5375 - 5379
(2018/09/13)
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- Catalytic activity of molybdenum(II) complexes in homogeneous and heterogeneous conditions
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The new complexes [MoBr(η3-C3H5)(CO)2(L)2] (C1) and [MX2(CO)3(L)2] (M = Mo(II), X = I (C2); M = Mo(II), X = Br (C3); M = W(II), X = I (C4); M = W(II), X = Br (C5)) were synthesized by reaction of 2-amino-1,3,4-thiadiazole (L) with [MoBr(η3-C3H5)(CO)2(NCCH3)2] (1), [MoI2(CO)3(CH3CN)2](M = Mo (2); M = W (4)), or [MoBr2(CO)3(CH3CN)2](M = Mo (3); M = W (5)) in 2:1 ratio. The five complexes were immobilized in MCM-41, yielding the materials MCM-Cn (n = 1-5), and C1 was also immobilized in silica gel (Silica-C1) and in a polyhedral oligomeric silsesquioxane (Cube-C1). Complexes and materials were fully characterized by spectroscopic techniques and elemental analysis. DFT calculations showed that several C1 isomers should coexist. The as synthesized and supported complexes were tested as catalysts on the oxidation of geraniol, cis-hex-3-en-1-ol, trans-hex-3-en-1-ol, (S)-limonene, and 1-octene. The conversions and TOF significantly depend on the complex and the nature of the substrate. The general conclusions are (i) complex C1 has the highest activity; (ii) tungsten complexes C4 and C5 are more active than the molybdenum analogues; (iii) the immobilization of the catalysts improves the performance; and (iv) silica gel and the polyhedral oligomeric silsesquioxane supports modify the selectivity, leading to products different from the one obtained with MCM for specific substrates.
- Vasconcellos Dias, Maria,Saraiva, Marta S.,Ferreira, Paula,Calhorda, Maria José
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p. 1465 - 1478
(2015/05/13)
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- Eu(OTf)3-Catalyzed highly regioselective nucleophilic ring opening of 2,3-epoxy alcohols: An efficient entry to 3-substituted 1,2-diol derivatives
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In our study of the total synthesis of (+)-irciniastatin A, we found a need to develop a method that enables a C3-selective nucleophilic ring opening of 2,3-epoxy alcohol by MeOH, by which we found that the use of combined catalytic amounts of Eu(OTf)3 and 2,6-di-tert-butyl-4-methylpyridine (DTBMP) enables the intended transformation to obtain 3-methoxy-1,2-diol efficiently. Promising features of a protocol that effects a highly regioselective nucleophilic ring opening of 2,3- and 3,4-epoxy alcohols using various nucleophiles including alcohols, thiols, and unprotected amines are described.
- Uesugi, Shun-Ichiro,Watanabe, Tsubasa,Imaizumi, Takamichi,Shibuya, Masatoshi,Kanoh, Naoki,Iwabuchi, Yoshiharu
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supporting information
p. 4408 - 4411
(2015/01/16)
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- An efficient recyclable peroxometalate-based polymer-immobilised ionic liquid phase (PIILP) catalyst for hydrogen peroxide-mediated oxidation
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A linear cation-decorated polymeric support with tuneable surface properties and microstructure has been prepared by ring-opening metathesis polymerisation (ROMP) of a pyrrolidinium-functionalised norbornene-based monomer with cyclooctene. The derived peroxophosphotungstate-based polymer-immobilised ionic liquid phase (PIILP) catalyst is an efficient and recyclable system for the epoxidation of allylic alcohols and alkenes, with only a minor reduction in performance on successive cycles.
- Doherty, Simon,Knight, Julian G.,Ellison, Jack R.,Weekes, David,Harrington, Ross W.,Hardacre, Christopher,Manyar, Haresh
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supporting information; experimental part
p. 925 - 929
(2012/06/18)
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- Ring-opening hydrofluorination of 2,3- and 3,4-epoxy amines by HBF 4·OEt2: Application to the asymmetric synthesis of (S, S)-3-deoxy-3-fluorosafingol
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Treatment of a range of 2,3- and 3,4-epoxy amines with HBF 4·OEt2 at room temperature results in fast and efficient SN2-type ring-opening hydrofluorination to give stereodefined amino fluorohydrins. Operational simplicity, scalability, and short reaction time at ambient temperature are notable features of this method. The utility of this methodology is exemplified in a concise asymmetric synthesis of (S,S)-3-deoxy-3-fluorosafingol.
- Cresswell, Alexander J.,Davies, Stephen G.,Lee, James A.,Morris, Melloney J.,Roberts, Paul M.,Thomson, James E.
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experimental part
p. 4617 - 4627
(2011/07/30)
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- 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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supporting information; experimental part
p. 6997 - 7004
(2009/09/30)
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- An improved iron-catalyzed epoxidation of aromatic and aliphatic olefins with hydrogen peroxide as oxidant
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A convenient and practical method for the iron-catalyzed epoxidation of aromatic and aliphatic olefins is described. The iron catalyst system is generated in situ from iron trichloride hexahydrate, pyridine-2,6-dicarboxylic acid (H2pydic), and benzylamines. By variation of the benzylamine ligand, a variety of aliphatic and aromatic olefins were oxidized in high yield (up to 96%) and good-to-excellent selectivity in the presence of hydrogen peroxide as the terminal oxidant. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Bitterlich, Bianca,Schroeder, Kristin,Tse, Man Kin,Beller, Matthias
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scheme or table
p. 4867 - 4870
(2009/05/26)
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- Polyfluorinated quaternary ammonium salts of polyoxometalate anions: Fluorous biphasic oxidation catalysis with and without fluorous solvents
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[Matrix presented] Polyfluorinated quaternary ammonium cations, [CF 3(CF2)7(CH2)3] 3CH3N+ (RFN+), were synthesized and used as countercations for the [WZnM2(H 2O)2(ZnW9O34)2] 12- (M = Mn(II), Zn(II)) polyoxometalate. The (RFN +)12[WZnM2(H20)2 (ZnW9O34)2] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected by both the hydrophobicity of the solvent and the substrate.
- Maayan, Galia,Fish, Richard H.,Neumann, Ronny
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p. 3547 - 3550
(2007/10/03)
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- Epoxidation of olefins
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A method for producing an epoxide from an olefin using a mixture hydrogen peroxide, a nitrile compound and a ketone is disclosed.
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- Epoxidation of alkenes with H2O2 generated in situ from alcohols and molecular oxygen using N-hydroxyphthalimide and hexafluoroacetone as catalysts
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A new epoxidation method of olefins with hydrogen peroxide and/or α- hydroxy hydroperoxide which are generated in situ from an alcohol and molecular oxygen was developed. A variety of alkenes were smoothly epoxidized with molecular oxygen in the presence of an alcohol under the influence of hexafluoroacetone (HFA) and N-hydroxyphthalimide (NHPI) as catalysts. The reaction involves the formation of α-hydroxy hydroperoxide and/or hydrogen peroxide derived from 1-phenylethanol and dioxygen by the action of NHPI and the active oxygen transfer from these hydroperoxides to HFA, giving 2- hydroperoxyhexafluoro-2-propanol which serves as the actual epoxidizing agent.
- Iwahama, Takahiro,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 693 - 705
(2007/10/03)
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- One-pot synthesis of cycloalkane derivatives using allyl phenyl sulfone and epoxymesylate
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One-pot synthesis of cycloalkane derivatives using an anion of allyl phenyl sulfone and epoxymesylate is presented. (C) 2000 Elsevier Science Ltd.
- Miyaoka, Hiroaki,Shigemoto, Tatsuya,Shinohara, Ikuo,Suzuki, Atsushi,Yamada, Yasuji
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p. 8077 - 8081
(2007/10/03)
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- Efficient epoxidation of alkenes with aqueous hydrogen peroxide catalyzed by methyltrioxorhenium and 3-cyanopyridine
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The epoxidation of alkenes with 30% aqueous hydrogen peroxide is catalyzed efficiently by methyltrioxorhenium (MTO) in the presence of pyridine additives. The addition of 1-10 mol % of 3-cyanopyridine increases the system's efficiency for terminal and trans-disubstituted alkenes resulting in high isolated yields of the corresponding epoxides. The system allows for epoxidation of alkenes with various functional groups. Alkenes leading to acid-sensitive products are efficiently epoxidized using a mixture of pyridine and 3-cyanopyridine as additives. This method is operationally very simple and uses an environmentally benign oxidant. The effects of different pyridine additives on the alkene conversion and the catalyst lifetime are discussed.
- Adolfsson,Coperet,Chiang,Yudin
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p. 8651 - 8658
(2007/10/03)
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- Selective epoxidation in dense phase carbon dioxide
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Selective epoxidations with transition metal catalysts (V, Ti, Mo) and ButOOH proceed with high conversions and high selectivity in dense phase carbon dioxide.
- Pesiri, David R.,Morita, David K.,Glaze, William,Tumas, William
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p. 1015 - 1016
(2007/10/03)
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- Diastereoselective epoxidation of allylic alcohols by t-Butyl hydroperoxide/zeolites system
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Commercial zeolites promotes the epoxidation of unsaturated alcohols in chemo- and diastereoselective way.
- Palombi, Laura,Bonadies, Francesco,Scettri, Arrigo
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p. 11369 - 11376
(2007/10/03)
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- Regioselective nucleophilic ring opening of epoxides and aziridines derived from homoallylic alcohols
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The regioselectivity of nuclcopbilic ring opening of some 3,4-epoxy and 3,4-aziridino alcohols has been studied. The nucleophiles chosen were complex hydrides (LiAlH4, Red-Al and DIBAL) and Lipshutz- or Gilman-type organocuprate reagents. The C-4 substituent in the substrates was varied in order to study steric and electronic effects on the ring opening reactions. For alkyl substituents at C-4, most of the results can be explained on the basis of intramolecular delivery of the nucleophile to C-3 via a six-membered transition state, leading to 1,4-diols or 1,4-amine alcohol derivatives. In general, the epoxy alcohols gave poorer regioselectivity than the N-tosyl aziridino alcohols, for which selectivities of >95:5 were routinely obtained. The activating effect of a phenyl group at C-4 led to a switch in regiochemistry, with the 1,3-diol or 1,3-amino alcohol derivative as the major product.
- Tanner, David,Groth, Thomas
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p. 16139 - 16146
(2007/10/03)
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- Diastereoselective epoxidation of olefins by organo sulfonic peracids, II
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We have investigated the behaviour of sulfonic peracids 2 in situ generated towards olefins 7a, 7b, 9, 11, 14, 16, 18, allylic acid and homoallylic alcohols 20, 22, 24, 26, 28, 30, 33 and α,β-unsaturated ketones 35, 37, 39. Generally, the epoxidation proceeds in a peracid-like manner with greater diastereoselectivity than those by common oxidants. In particular, the epoxidation of Δ4 3-ketosteroids 39a-i led to 4α,5α-epoxides 40a-i with remarkable high de-values. Enhanced α-selectivity was also found in the epoxidation of cholesterol 28b. Due to the mild reaction conditions, even acid sensitive epoxides 8a, 8b, 10, 12, 13, 15, 17, 19 were obtained in good yields.
- Kluge,Schulz,Liebsch
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p. 2957 - 2976
(2007/10/03)
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- Tetracyanoethylene-hydrogen peroxide, a mild epoxidation system of olefins
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A reagent combination system, tetracyanoethylene-30% hydrogen peroxide, was found to epoxidize olefins efficiently in acetonitrile at room temperature in a stereospecific manner with retention of the configuration of the double bond.
- Masaki,Miura,Mukai,Iwata,Oda,Itoh
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p. 686 - 688
(2007/10/03)
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- Regiochemical control of the ring opening of 1:2-epoxides by means of chelating processes. 10. Synthesis and ring opening reactions of mono- and difunctionalized cis and trans aliphatic oxirane systems
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The regiochemical outcome of the ring opening of 1:2-epoxides through chelation processes assisted by metal ions, was verified in mono- and difunctionalized aliphatic oxirane systems bearing the heterofunctionality (OR) in an homoallylic and/or allylic relationship to the oxirane ring. The effect of the distance of the OR functionality from the oxirane ring and of the type of protective group on the regiochemical outcome of these systems is examined. In some cases, the use of LiClO4 or Mg(ClO4)2 as the promoting metal salt makes it possible the obtainment of a nice regioalternating process.
- Azzena, Francesca,Calvani, Federico,Crotti, Paolo,Gardelli, Cristina,Macchia, Franco,Pineschi, Mauro
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p. 10601 - 10626
(2007/10/02)
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- Sharpless epoxidation by in situ generation of furylhydroperoxides
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The compatibility of the generation of furylhydroperoxides by a radical chain process with the presence of oxygen acceptors and transition metal catalysts allows the achievement of a modified Sharpless procedure for the epoxidation of allylic alcohols and oxidation of sulphides to sulphoxides.
- Antonioletti,Bonadies,Lattanzi,Monteagudo,Scettri
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p. 5433 - 5436
(2007/10/02)
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- Ethyl Cyanoformate/Hydrogen Peroxide and Related Combination Systems, Novel Epoxidizing Systems of Olefins
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A combination system of ethyl cyanoformate and hydrogen peroxide was found to epoxidize olefins in a stereospecific manner at room temperature.Asymmetric epoxidation was observed with menthyl cyanoformate/hydrogen peroxide system.
- Masaki, Yukio,Miura, Tsuyoshi,Mukai, Isao,Itoh, Akichika,Oda, Hirohisa
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p. 1937 - 1940
(2007/10/02)
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