- Inverse phase transfer catalysis. III.- Optimization of the epoxidation reaction of α,β-unsaturated ketones by hydrogen peroxide
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The epoxidation of chalcone using hydrogen peroxide in the presence of a base in a two-phase medium system following the so-called Inverse Phase Transfer Catalysis (IPTC) process was investigated. Careful examination of various parameters including surfactant concentration, pH, H2O2 decomposition side-reactions and epoxide ring-opening, allowed us to determine optimal experimental conditions.
- Boyer, Bernard,Hambardzoumian, Araik,Roque, Jean-Pierre,Beylerian, Norair
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- An economically viable route to cis/trans-(±)-2,2-dimethyl-3-(2',2'-dichlorovinyl) cyclopropane carboxylic acid esters
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A short and economically viable synthesis of 5-(2',2'-dichloroethenyl)dihydro-4,4-dimethyl-2(3H)-furanone, 3, an important intermediate for the preparation of cis/trans-(±)-1, from isophorone, 2, is described.
- Mandal,Borude
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- Novel cyclic ketones for catalytic oxidation reactions
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In our effort to search for C2 symmetric and conformationally rigid chiral ketones as catalysts for asymmetric epoxidation, a series of cyclic ketones 4-10 were prepared from the corresponding diacids. Compared with acyclic ketones for epoxidation of trans-stilbene, those 9-, 10-, and 11- membered-ring cyclic ketones were found to have much higher catalytic activities, which were attributed to steric effects, electronic effects, and ring strains. By using the homogeneous acetonitrile-water solvent system, unfunctionalized olefins with various substitution patterns (with 5 mol % of ketone 9) and strongly electron-deficient olefins (with a 1:1 ketone 9:substrate ratio) were epoxidized with Oxone as terminal oxidant in 75-96% yield at room temperature and neutral pH. In addition, oxidation of alcohols (with 20 mol % of ketone 9) was carried out successfully with good isolated yields of aldehydes or ketones (75-88%).
- Yang, Dan,Yip, Yiu-Chung,Tang, Man-Wai,Wong, Man-Kin,Cheung, Kung-Kai
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- A novel allylic hydroxylation of sterically hindered olefins by Fe-porphyrin-catalyzed mCPBA oxidation
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A novel allylic hydroxylation by mCPBA of triterpenes bearing sterically hindered olefin is catalyzed by Fe(PFPP)Cl. Oleanolic acid, ursolic acid, dihydrolanosterol and their derivatives are converted to the corresponding allylic alcohols by mCPBA-Fe(PFPP)Cl under mild conditions. In contrast, for common or electron-deficient olefins, mCPBA-Fe(PFPP)Cl is an efficient epoxidation system. The intermediacy of an Fe-oxo-porphyrin and subsequent hydrogen abstraction and recombination are proposed for the selective α-hydroxylation of triterpenes.
- Konoike, Toshiro,Araki, Yoshitaka,Kanda, Yasuhiko
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- Epoxydation of activated olefins by solid bases
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The epoxidation of 2,1-cyclohexenone and β-isophorone by H2O2 and tert-butyl hydroperoxide (TBHP) were investigated on catalysts: hydrotalcites activated in different conditions, fluorinated hydrotalcites, KF/Al2O3/s
- Figueras,Palomeque,Lopez,Palomeque,Lopez
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- Metal and solvent-free oxidation of α-isophorone to ketoisophorone by molecular oxygen
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The metal and solvent-free oxidation of α-isophorone to ketoisophorone (KIP) using N-hydroxy phthalimide (NHPI) as the catalyst under atmospheric oxygen was studied, eliminating the isomerization process of α-isophorone to β-isophorone. The effect of co-catalyst, temperature, time, amount of NHPI, and recycling on the oxidation was investigated. The oxidation of α-isophorone proceed well without any co-catalyst under 60 °C for 10 h, which was different with the traditional oxidation of α-isophorone at high temperature. Furthermore, NHPI can be easily separated and reused with a slight loss on its activity. This aerobic oxidation process by NHPI provides a good alternative way for the industrial synthesis of KIP.
- Wang, Congmin,Wang, Guoliang,Mao, Jianyong,Yao, Zhen,Li, Haoran
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- Sustainable Epoxidation of Electron-Poor Olefins with Hydrogen Peroxide in Ionic Liquids and Recovery of the Products with Supercritical CO2
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An efficient procedure is described for the epoxidation of electron-deficient olefins, in particular Vitamin K3 and analogues, with aqueous basic solutions of hydrogen peroxide in different ambient temperature ionic liquids (ILs) [bmim+][X-] {[bmim +] = 1-butyl-3-methylimidazolium; [X-] = [BF 4-], [CF3SO3-], [PF 6-], [N(CF3SO2)2 -]}. Various factors affecting epoxide yield (in the range 80-99%), reaction rate and reproducibility have been examined. The almost quantitative extraction of the epoxides from the reaction media has been obtained with supercritical CO2. The ionic liquid was then recovered and reused in subsequent cycles. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Bortolini, Olga,Campestrini, Sandro,Conte, Valeria,Fantin, Giancarlo,Fogagnolo, Marco,Maietti, Silvia
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- Comparison of several heterogeneous catalysts in the epoxidation of α-isophorone with hydroperoxides
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Three different methods of epoxidation using heterogeneous catalysts are compared, under different conditions, in the benchmark epoxidation of α-isophorone. The use of tert-butyl hydroperoxide/KF-Al2O3 in toluene leads to the highest (almost quantitative) yield, whereas the system H2O2/hydrotalcite leads to the best result described to date using this oxidant.
- Fraile,Garcia, Jose I.,Mayoral, Jose A.,Figueras, Francois
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- Two catalytic systems of l-proline/Cu(II) catalyzed allylic oxidation of olefins with tert-butyl hydroperoxide
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The nontoxic and water-soluble l-proline combined with two different forms of copper(ii): recoverable Cu-Al hydrotalcite-like compounds (Cu-Al HTLcs) and water-soluble CuCl2, as a heterogeneous catalytic system (l-proline/Cu-Al HTLcs) and two-phase catalytic system (l-proline/CuCl2) to catalyze allylic oxidation with tert-butyl hydroperoxide. The results showed that l-proline/Cu(ii) is highly active for oxidizing isophorone (IP) into ketoisophorone (KIP). Maximum catalytic effects were afforded respectively under the optimal reaction conditions, which obtained 77.9% IP conversion with 74.3% KIP selectivity catalyzed by l-proline/Cu-Al HTLcs and 73.5% conversion with 81.6% selectivity by l-proline/CuCl2. Recycling experiments of the two catalytic systems of l-proline/Cu(ii) showed they are stable and recyclable for at least six cycles with appreciable catalytic activity. And various hydrocarbons could be smoothly transformed into corresponding ketones with satisfactory conversion and selectivity by the two catalytic systems.
- Yu, Peng,Zhou, Yin,Yang, Yingwei,Tang, Ruiren
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- Epoxyisophorone ring-opening: An efficient route for the introduction of functional groups at position 2 of isophorone
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Functional groups were selectively introduced at the C-2 position of isophorone via the epoxide ring-opening with several nucleophiles. Various behaviours were observed depending on the reaction conditions and the nature of nucleophilic reagents. Electronic and steric effects of the reactants were discussed. The best experimental systems involved LiClO4 salt effect in acetonitrile, phase transfer catalysis or KF-alumina under solvent-free conditions under microwaves.
- Rissafi,Rachiqi,El Louzi,Loupy,Petit,Fkih-Tétouani
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- Microwave Promoted Epoxidation of α,β-Unsaturated Ketones in Aqueous Sodium Perborate
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A series of α,β-unsaturated ketones has been treated with sodium perborate in water and 1,4-dioxane under microwave irradiation to produce α,β-epoxyketones in good yields.
- Sharifi, Ali,Bolourtchian, Mohammad,Mohsenzadeh, Farshid
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- Steel-promoted oxidation of olefins in supercritical carbon dioxide using dioxygen in the presence of aldehydes
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Oxidation of olefins occurs effectively in supercritical carbon dioxide as the reaction medium with dioxygen as the primary oxidant and aldehydes as sacrificial co-oxidants. No catalyst is required, but the reaction is promoted by the stainless steel of the reactor walls. Depending on the substrate, vinylic oxidation or epoxidation can be the prevailing pathway. Epoxidation is particularly effective for substrates with internal double bonds and for long-chain terminal olefins.
- Loeker, Frank,Leitner, Walter
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- Ultrasound-assisted epoxidation of olefins and α,β-unsaturated ketones over hydrotalcites using hydrogen peroxide
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An efficient ultrasound-assisted epoxidation of olefins and α,βunsaturated ketones over hydrotalcite catalysts in the presence of hydrogen peroxide and acetonitrile is described. This general and selective protocol is relatively fast and is applicable to a wide variety of substrates.
- Pillai, Unnikrishnan R.,Sahle-Demessie, Endalkachew,Varma, Rajender S.
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- Electrochemical Epoxidation of Electron-Poor Olefins Using Silver Bipyridine Based Redox Mediators
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Electrogenerated and regenerated silver(III)oxo bis(2,2'-bipyridine) and similar complexes can act as redox catalysts for the indirect electrochemical epoxidation of electron-deficient olefins in aqueous acetonitrile.Thus, isobutyl methacrylate is electrolyzed to form the epoxide with 87percent material yield and 21percent current yield.
- Kandzia, Christof,Steckhan, Eberhard
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- Epoxidation of α,β-unsaturated ketones with sodium perborate
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α,β-Unsaturated ketones are rapidly converted to epoxyketones at room temperature in aqueous sodium perborate in the presence of a phase transfer catalyst. Organic solvents can be used to modify the rate of epoxidation.
- Straub, Thomas S.
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- One-Pot Biocatalytic Double Oxidation of α-Isophorone for the Synthesis of Ketoisophorone
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The chemical synthesis of ketoisophorone, a valuable building block of vitamins and pharmaceuticals, suffers from several drawbacks in terms of reaction conditions and selectivity. Herein, the first biocatalytic one-pot double oxidation of the readily available α-isophorone to ketoisophorone is described. Variants of the self-sufficient P450cam-RhFRed with improved activity have been identified to perform the first step of the designed cascade (regio- and enantioselective allylic oxidation of α-isophorone to 4-hydroxy-α-isophorone). For the second step, the screening of a broad panel of alcohol dehydrogenases (ADHs) led to the identification of Cm-ADH10 from Candida magnoliae. The crystal structure of Cm-ADH10 was solved and docking experiments confirmed the preferred position and geometry of the substrate for catalysis. The synthesis of ketoisophorone was demonstrated both as a one-pot two-step process and as a cascade process employing designer cells co-expressing the two biocatalysts, with a productivity of up to 1.4 g L?1 d?1.
- Tavanti, Michele,Parmeggiani, Fabio,Castellanos, J. Rubén Gómez,Mattevi, Andrea,Turner, Nicholas J.
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- Metal-free allylic oxidation with molecular oxygen catalyzed by g-C 3N4 and N-hydroxyphthalimide
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Polymeric graphitic carbon nitride (g-C3N4) is a layered graphite-like nitrogen-rich material, bearing the potential ability to reductively adsorb molecular oxygen for catalytic allylic oxidation. Furthermore, N-hydroxyphthalimide (NHPI) has been recognized as an efficient catalyst for aerobic oxidation of various organic compounds under mild conditions in the presence of various co-catalysts. We present here a promising strategy for employing such nitride-rich g-C3N4 combined with NHPI to form an all-organic metal-free composite and have examined its activity for allylic oxidation with molecular oxygen as the primary terminal oxidant. In the case of allylic oxidation α-isophorone catalyzed by g-C3N4/NHPI gave priority to its corresponding carbonyl compound and epoxide. The effects of various reaction conditions on the catalytic reaction were optimized, affording 74.8 % conversion with 44.4 % selectivity of ketoisophorone at 130 C in 5 h. Repeated runs demonstrated that the catalyst was stable for at least three cycles without noticeable loss of its catalytic activity. Graphical Abstract: [Figure not available: see fulltext.]
- Liu, Guiyin,Tang, Ruiren,Wang, Zhen
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- Novel catalytic system: N-hydroxyphthalimide/hydrotalcite-like compounds catalysing allylic carbonylation of cyclic olefins
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N-hydroxyphthalimide (NHPI) combined with stable and recoverable transition metal-aluminium binary hydrotalcite-like compounds (M-Al HTLcs, M = Cu, Ni, Co) as an unprecedented catalytic system was demonstrated for the allylic carbonylation, as the model reaction, of cyclic olefins with tert-butyl hydroperoxide (TBHP), using isophorone (IP) to ketoisophorone (KIP). The results showed NHPI combined with Cu-Al HTLcs to be an efficient catalytic system and the influences of various reaction conditions of the catalytic reaction were optimised. A maximum IP conversion of 68.0 % with 81.8 % selectivity to KIP was afforded under the optimal reaction conditions. Experiments of repeatability and restorability showed Cu-Al HTLcs to be stable for at least five cycles without noticeable loss of catalytic activity. Expanding substrates could also be efficiently converted to the corresponding ketones under the optimised reaction conditions with appreciable yields. A plausible catalytic reaction mechanism was proposed.
- Zhou, Yin,Tang, Rui-Ren,Song, Dan
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- Electrosynthesis of hydrogen peroxide in room temperature ionic liquids and in situ epoxidation of alkenes
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Hydrogen peroxide can be electrosynthesized from oxygen in [bmim][BF 4]-water and used in situ for the epoxidation of alkenes. The Royal Society of Chemistry 2005.
- Tang, Michael Chi-Yung,Wong, Kwok-Yin,Chan, Tak Hang
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- Epoxidation of α-isophorone with amine-modified titania-silica hybrid aerogel: Evidence for Ti-amine interaction
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The oxidation of α-isophorone was selected as a test reaction to evaluate the newly developed organically modified aerogels in the epoxidation of deactivated olefins and to elucidate the role of organic modification in the epoxidation reaction. The catalyst used was an N,N-dimethyl-3-aminopropyl-modified titania-silica mixed oxide containing ~ 9 wt % TiO2, showing exceptional activity and 94% epoxide selectivity at 91% peroxide conversion in the epoxidation of cyclohexanol with tert-butylhydroperoxide. Organic modification diminished the epoxidation activity of titania-silica and eliminated the activity in acid-catalyzed side reactions, such as epoxide and peroxide decomposition. Methanol addition to an unmodified aerogel had a similar effect. Electron donation by the alkylamino groups or methanol to the titanium active site (Lewis acid) suppressed its acidity and, thus the rate of acid-catalyzed oxidation and isomerization reactions. The surface Si-OH groups (Broensted sites) of titania-silica were poor catalysts for epoxide decomposition.
- Baiker,Muller,Schneider,Mallat
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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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- Microwave-expedited olefin epoxidation over hydrotalcites using hydrogen peroxide and acetonitrile
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An efficient microwave-assisted epoxidation of olefins is described over hydrotalcite catalysts in the presence of hydrogen peroxide and acetonitrile. This general and selective protocol is extremely fast and is applicable to a wide variety of substrates.
- Pillai, Unnikrishnan R,Sahle-Demessie, Endalkachew,Varma, Rajender S
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- Selective Epoxidation of α-Isophorone with Mesoporous Titania-Silica Aerogels and tert-Butyl Hydroperoxide
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Amorphous, mesoporous TiO2-SiO2 mixed oxides, synthesised using a sol-gel process followed by extraction with supercritical CO2, show high selectivities (98percent) in the heterogeneous epoxidation of α-isophorone in ethylbenzene at 60 deg C.
- Hutter, R.,Mallat, T.,Baiker, A.
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- Identification of a discrete peroxide dianion, O22-, in a two Sodium-(l,6-Anhydro-β-maltose)2-Peroxide complex
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A complex formed by two l,6-anhydro-β-maltoses with peroxide and two sodium ions has been isolated and determined to be [Na2(1,6-anhydro-β-maltose)2(H2O)3]O2 by X-ray crystallography. The O2 moiety, 1.496(2) A for the O-O distances in the complex was identified as a discrete peroxide dianion, whereas two sodium and two carbohydrate molecules constitute a binuclear complex counter cation.The complex containing the discrete peroxide dianion was proven to be a useful oxidizing agent, which successfully oxidized α,β-unsaturated ketone to epoxyketone.
- Kato, Takayuki,Fujimoto, Takashi,Tsutsui, Ayumi,Tashiro, Mitsuru,Mitsutsuka, Yoshihiro,Machinami, Tomoya
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- Preparation of SnO2/graphene nanocomposite and its application to the catalytic epoxidation of alkenes with H2O2
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The in situ growth of SnO2 nanoparticles on graphene have been achieved via a hydrothermal method and the nanocomposites were used as an efficient catalyst for the epoxidation of alkenes with aqueous hydrogen peroxide in nitrile based systems for the first time. Furthermore, the SnO2/graphene nanocomposites could be readily recovered and reused for at least ten consecutive cycles without significant loss of activity and selectivity.
- Liu, Min,Wang, Xiaozhong,Chen, Yingqi,Dai, Liyan
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- Neighbouring effects on catalytic epoxidation by Fe-cyclam in M2-PDIxCy complexes
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The unsymmetric PDIeCy ligand, featuring pyridinediimine and cylam sites, can be selectively metalated. Complementing the diiron compound, we have synthesized two heterobimetallic isomers, [ZnPDIFeCy(PDIeCy)(OTf)4] (3) and [FePDIZnCy(PDIeCy)(OTf)4] (4), and a dizinc complex, [Zn2(PDIeCy)(OTf)4] (5). Olefin epoxidation by the series of complexes was investigated. The M-PDI site influences the reactivity of the M-cyclam, resulting in increased activity toward enones. This journal is
- Hofmann, Andreas J.,Niederegger, Lukas,Hess, Corinna R.
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supporting information
p. 17642 - 17648
(2020/12/30)
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- Improving the Monooxygenase Activity and the Regio- and Stereoselectivity of Terpenoid Hydroxylation Using Ester Directing Groups
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The monooxygenase enzyme CYP101B1, from Novosphingobium aromaticivorans DSM12444, binds norisoprenoids more tightly than monoterpenoids and oxidized these substrates with high regioselectivity. Ionols bound less tightly to CYP101B1 than ionones, but the levels of product formation remained high and the selectivity of oxidation was similar to that observed for the parent norisoprenoid. The structurally related sesquiterpene lactone (+)-sclareolide (9) was stereoselectively hydroxylated by CYP101B1 to (S)-(+)-3-hydroxysclareolide (9a). The turnover of monoterpenoid derivatives showed low levels of product formation and selectivity despite promising binding data. CYP101B1 catalyzed the selective oxidation of (1R)-(-)-nopol (14) and cis-jasmone (15), generating >90% (1R)-(-)-5-hydroxynopol (14a) and 4-hydroxy-cis-jasmone (15a), respectively. To develop strategies for the efficient and selective oxidation of monoterpenoid-based substrates using CYP101B1, we investigated the binding and catalytic properties of terpenoid acetates. The ester functional group of these substrates mimicked the carbonyl moiety of norisoprenoids and anchored the monoterpenoid acetates in the active site of CYP101B1 with high affinity for the monoterpenoid acetates. The oxidation of these substrates by CYP101B1 occurred with product formation rates in excess of 1000 min-1 and total turnover numbers of greater than 5000 being observed in all but one instance. Critically, the oxidations were regioselective, with several being stereoselective. (-)-Myrtenyl acetate (20) was oxidized regioselectively (>95%) to yield cis-4-hydroxy-myrtenyl acetate (20a), which was further oxidized to 4-oxomyrtenyl acetate (20b) using a whole-cell system, providing a biocatalytic route to generate intermediates used in the production of cannabinoid derivatives. The ester carbonyl moiety could also be used as a directing group also to enhance the activity and control the selectivity of P450-catalyzed reactions; for example, the turnover of l-(-)-bornyl acetate (18) and isobornyl acetate (19) by CYP101B1 generated 9-hydroxybornyl acetate (18a) and 5-exo-hydroxyisobornyl acetate (19a), respectively, as the sole products.
- Hall, Emma A.,Sarkar, Md. Raihan,Lee, Joel H. Z.,Munday, Samuel D.,Bell, Stephen G.
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p. 6306 - 6317
(2016/09/09)
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- HSP-90 BINDING COMPOUNDS, COMPOSITIONS THEREOF, AND THEIR USE IΝ THE TREATMENT AND PREVENTION OF FUNGAL INFECTIONS
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The invention relates to therapeutic compounds that bind to HSP90. The compounds disclosed herein bind HSP90 and alter the chaperoning capability of HSP90 proteins. The invention also relates to pharmaceutical compositions comprising these compounds, and methods of treating or preventing fungal infections.
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Page/Page column 43
(2012/10/08)
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- An efficient and mild oxidation of α-isophorone to ketoisophorone catalyzed by N-hydroxyphthalimide and copper chloride
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N-hydroxyphthalimide (NHPI) and copper chloride (CuCl2) were first utilized for aerobic oxidation of α-isophorone (α-IP) to ketoisophorone (KIP) and the effects of co-catalysts, temperature, reaction time, solvent, amount of CuCl2 and pressure of oxygen were investigated extensively. NHPI/CuCl2 turned out to be highly efficient to this oxidation with up to 91.3% conversion and 81.0% selectivity under mild conditions. And various hydrocarbons including benzylic compounds, cycloalkene and its derivatives were also oxidized smoothly under optimized conditions. Moreover, the possible reaction mechanism was proposed and verified by FT-IR spectra.
- Chen, Lihua,Tang, Ruiren,Li, Zhongying,Liang, Shan
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experimental part
p. 459 - 463
(2012/05/20)
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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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- HSP-90 BINDING COMPOUNDS, COMPOSITIONS THEREOF, AND THEIR USE FN THE TREATMENT OF AUTOIMMUNE AND INFLAMMATORY DISEASES
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The invention relates to therapeutic compounds that bind to HSP90. The compounds disclosed herein bind HSP90 and alter the chaperoning capability of HSP90 proteins. The invention also relates to pharmaceutical compositions comprising these compounds, and methods of treating diseases and disorders such as cancer, autoimmune disease and other diseases.
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Page/Page column 55; 56
(2011/04/24)
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- Preparation and regioselective SN2′ reaction of novel gem-difluorinated vinyloxiranes with RLi
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A series of hitherto unknown 3,4-epoxy-1,1-difluorobutenes were prepared from the readily accessible α,β-epoxy ketones and these compounds were found to undergo regioselective SN2′ reactions with hard RLi nucleophiles occurring at the highly positively charged terminal fluorine-possessing sp2 carbon atom in quite sharp contrast to the cases of the corresponding nonfluorinated vinyloxiranes which only attained a low level of regioselectivity. Addition of HMPA substantially improved the products' olefinic stereoselectivity. Theoretical calculations were used to qualitatively explore the nature of selectivity in these reactions.
- Ueki, Hisanori,Chiba, Takashi,Yamazaki, Takashi,Kitazume, Tomoya
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p. 7616 - 7627
(2007/10/03)
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- Synthesis of alkylated iridolactone analogs
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Bicyclic δ-lactones, iridolactones analogs with an alkyl group at the bicyclic junction, are obtained from α-alkyl-α-hydroxymethylcyclopentanones via an intramolecular Horner-Wadsworth-Emmons reaction.
- Guerrab, Zineb,Daou, Boujemaa,Fkih-Tetouani, Souad,Ahmar, Mohammed,Cazes, Bernard
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p. 5727 - 5730
(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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- Lithium naphthalenide induced reductive cleavage of α,β-epoxy ketones: An efficient procedure for the preparation of β-hydroxy ketones
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Lithium naphthalenide presents itself as a mild and efficient reagent for the cleavage of α,β-epoxy ketones to give the corresponding β-hydroxy ketones in good yields.
- Jankowska, Renata,Mhehe, George L.,Liu, Hsing-Jang
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p. 1581 - 1582
(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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- Structure-odor correlation, XXIV: Synthesis and olfactory properties of damascene and damascenone analogs
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The aldehydes rac-1, rac-2, and 3 were conveniently prepared by starting from isophorone (4). Reaction of 1-3 with (E,Z)-1-bromo-1-propene (14) afforded the rac-allylic alcohols (E,Z)-15, -18, and -20. The alcohols were oxidized to the damascone/damascenone analogs 1-(3,5,5-trimethyl-2-cyclohexen-1-yl)- (rac-16), 1-(3,5,5-trimethyl-1-cyclohexen-1-yl)-(rac-19), and 1-(3,5,5-trimethyl-1,3-cyclohexadien-1-yl)-2-buten-1-one (21), and the (E/Z) isomers were separated by FC. Their olfactory evaluation shows that the highly estimated odor of damascone (A, B) and damascenone (C) is more or less lost. This result can be explained by force-field calculation of the lowest energy conformation of 16, 19, and 21 in comparison with those of A-C. VCH Verlagsgesellschaft mbH, 1996.
- Weyerstahl, Peter,Licha, Kai
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p. 809 - 814
(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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- Hydrotalcite-Promoted Epoxidation of Electron-Deficient Alkenes with Hydrogen Peroxide
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A synthetic anionic clay, hydrotalcite (Mg/Al=2.8), promotes the epoxidation of electrondeficient alkenes with H2O2.With open-chain, α,β-unsaturated carbonyl compounds 3-hydroxy-1,2-dioxolanes are also obtained.
- Cativiela, Carlos,Figueras, Francois,Fraile, Jose M.,Garcia, Jose I.,Mayoral, Jose A.
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p. 4125 - 4128
(2007/10/02)
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- Dioxiranes. 20. Preparation and properties of some new dioxiranes
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The in situ method for producing dioxiranes has been modified to permit the isolation in ketone solution of some nonvolatile dioxiranes. The dioxiranes have been characterized spectroscopically and, in some cases, by chemical reactions.
- Murray, Robert W.,Singh, Megh,Jeyaraman, Ramasubbu
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p. 1346 - 1351
(2007/10/02)
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- Dioxirane Epoxidation of α,β-Unsaturated Ketones
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The synthesis of epoxides 3a-r is achieved in excellent yields by reaction of the α,β-unsaturated ketones 1a-c, 4,4'-disubstituted (E)-chalcones 1d-o, and 2'-hydroxy-4-substituted (E)-chalcones 1p-r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methyl)dioxirane (2b).This method constitutes a useful alternative to the Weitz-Scheffer epoxidation (alkaline H2O2) of such electron-poor substrates.Key Words: Epoxidation / Dioxiranes / Ketones, α,β-unsatured / (E)-Chalcones / (E)-2'-Hydroxychalcones / 2-Cycloen-1-ones / Caroate
- Adam, Waldemar,Hadjiarapoglou, Lazaros,Smerz, Alex
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p. 227 - 232
(2007/10/02)
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- The reaction of trialkylstannylmethyllithium with α,β-epoxy ketones and α-chloro ketones
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The reactions of trialkylstannylmethyllithium with α,β-epoxy ketones afforded mainly cyclopropanols, while α-chloro ketones afforded allyl alcohols and/or cyclopropanols, in varying amounts depending upon the molar ratio of the reagent to the substrate.
- Sato, Tadashi,Kikuchi, Toshihiro,Tsujita, Hiroshi,Kaetsu, Atsushi,Sootome, Norio,Nishida, Ken-Ichiro,Tachibana, Kazutaka,Murayama, Eigoro
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p. 3281 - 3304
(2007/10/02)
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- Dimethyldioxirane epoxidation of α,β-unsaturated ketones, acids and esters
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The corresponding epoxides were isolated in excellent yields via oxygen transfer by dimethyldioxirane (as acetone solution).
- Adam, Waldemar,Hadjiarapoglou, Lazaros,Nestler, Bernd
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p. 331 - 334
(2007/10/02)
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- THE OXIDATION OF α-β-UNSATURATED KETONES IN AQUEOUS SODIUM PERBORATE
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A series of α-β-unsaturated ketones has been prepared with sodium perborate in water and a cosolvent to produce the corresponding epoxides in good yield.The reaction constitutes a mild and convenient method for the synthesis of α-β-epoxyketones.
- Reed, Kathryn L.,Gupton, John T.,Solarz, Traci L.
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p. 3579 - 3588
(2007/10/02)
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- PALLADIUM(II)-CATALYZED EPOXIDATION OF OLEFINS WITH α-SILYLOXYALKYL PEROXYBENZOATES
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A novel oxygen-atom-transfer reaction from α-silyloxyalkyl peroxybenzoate to olefins by palladium(II) catalyst to give epoxides has been described.
- Nagata, Ryu,Matsuura, Teruo,Saito, Isao
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p. 2691 - 2694
(2007/10/02)
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- Reaction of Epoxides with Triphenylphosphine-Thiocyanogen (TPPT): Preparation of α-Thiocyanatovinyl Ketones, vis-Dithiocyanates, and vic-Dithiocyanatohydrins
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A number of epoxides smoothly react with TPPT under mild conditions to give α-thiocyanatovinyl ketones, vic-dithiocyanates, or vic-thiocyanatohydrins, depending on the structures of the epoxides used.The reactions proceed site- and stereo-specifically, to give α-thiocyanatovinyl ketones from αβ-epoxyketones, threo-dithiocyanate from trans-epoxide, erythro-dithiocyanate from cis-epoxide, and vic-thiocyanatohydrins from 1,1-disubstituted or fused epoxides, respectively.A possible mechanism for these reactions is put forward.
- Tamura, Yasumitsu,Kawasaki, Tomomi,Yasuda, Hitoshi,Gohda, Noriko,Kita, Yasuyuki
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p. 1577 - 1581
(2007/10/02)
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- Synthesis of some bicyclooct-5-en-2-ones and bicyclooctan-2-ones. Rearrangement accompanying oxidative decarboxylation with lead tetraacetate
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1-Methoxy-2-methyl-1,4-cyclohexadiene (3), 2-methoxy-1-methyl-1,3-cyclohexadiene (2), and 2-methoxy-1,5,5-trimethyl-1,3-cyclohexadiene (14) on heating with maleic anhydride give 1-methoxy-endo-7-methylbicyclooct-5-ene-syn-2,3-dicarboxylic acid anhydride (7) and its 6-methoxy-1-methyl (16a) and 6-methoxy-1,8,8-trimethyl (16b) analogues, respectively.On hydrolysis 16a and 16b give the corresponding keto dicarboxylic acids, 18a and 18b, via keto anhydrides 17a and 17b.Treatment of 18b with lead tetraacetate gives 1,8,8-trimethylbicyclooct-5-en-2-one (19) together with products in which rearrangement to a bicyclooctane system has occured.Treatment of 17b with bis(triphenylphosphino)nickel dicarbonyl gives only 19; similar treatment of 17a gives 1-methylbicyclooct-5-en-2-one (1).Reaction of bicyclooctane-2,3-dione (27) with methyllithium gives 3-hydroxy-3-methylbicyclooctan-2-one (28), its dimer 31, and a diol 30.Treatment of 5-exo-acetoxy-1,5-endo-dimethyl-6-oxobicyclooctane-anti-2,3-dicarboxylic acid (37) with lead tetraacetate gives 3-endo-acetoxy-1,3-exo-dimethylbicyclooct-5-en-2-one (33) as a minor product; the major product is derived by rearrangement to a bicyclooctane system.It is proposed that this rearrangement, like that of 18b, involves oxidative decarboxylation of a single carboxylic acid group to give a carbonium ion that undergoes rearrangement via a 1,2-acyl migration.
- Yates, Peter,Langford, Gordon E.
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p. 344 - 355
(2007/10/02)
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