- Investigation of homopolymerization rate of perfluoro-4,5-substituted-2- methylene-1,3-dioxolane derivatives and properties of the polymers
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Five perfluoro-4,5-substituted-2-methylene-1,3-dioxolane monomers were synthesized. These monomers were found to readily polymerized by a free radical initiator in bulk and/or in solutions. Homopolymerization rates were determined using in situ 19F NMR measurements and found to be 0.25 to 1.66 × 10-4 mol L-1 s-1 in 1,1,2-trichlorotrifluoroethane at 41°C using the perfluorodibenzoyl peroxide as an initiator. The rates depend on the substituents on the 4 and 5 positions of the dioxolane. The purified polymers were thermally stable (up to 350°C). They show low refractive indexes (1.33-1.36 at 532 nm). They are transparent from UV to near IR region and have high glass transition temperatures (100-170°C).
- Yang, Yu,Mike?, Franti?ek,Yang, Liang,Liu, Weihong,Koike, Yasuhiro,Okamoto, Yoshiyuki
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Read Online
- AMBER ODORANT
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The present invention concerns compound of formula (I) in the form of any one of its stereoisomers or as a mixture thereof, and wherein R1 represents a hydrogen atom, a C1-3 alkyl group or C2-3 alkenyl group; X represents an oxygen atom when R2 represents a C1-4 alkyl group or C2-4 alkenyl group or X represents a CH2-O group when R2 represents a C2-4 alkenyl group or a MeC=O group. The use as a perfuming ingredient of the invention's compound and the invention's compound as part of a perfuming composition or of a perfuming consumer product are also part of the present invention.
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Page/Page column 29
(2020/12/11)
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- Microwave-Enhanced Coupling of Carboxylic Acids with Liquid Ketones and Cyclic Ethers Using Tetrabutylammonium Iodide/ t-Butyl Hydroperoxide
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The oxidative coupling of carboxylic acids with liquid ketones and cyclic ethers has been accomplished in minutes using t-butyl hydroperoxide in the presence of tetrabutylammonium iodide under microwave irradiation in the absence of a solvent. In addition to drastically shortening the reaction times, the use of microwaves resulted, in general, in yields equal to or higher than those obtained by conventional heating.
- Macías-Benítez, Pablo,Moreno-Dorado, F. Javier,Guerra, Francisco M.
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p. 6027 - 6043
(2020/05/22)
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- Exploring the catalytic activity of Lewis-acidic uranyl complexes in the nucleophilic acyl substitution of acid anhydrides
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The catalytic activities of several uranyl complexes, such as N,N′-disalicylidene-o-phenelyenediaminato(ethanol)dioxouranium(vi) (UO2(salophen)EtOH), bis(dibenzoylmethanato)(ethanol)dioxouranium(vi) (UO2(dbm)2EtOH), pentakis(N,N-dimethylformamide)dioxouranium(vi) ([UO2(DMF)5]2+), and tetrakis(triphenylphosphine oxide)dioxouranium(vi) ([UO2(OPPh3)4]2+), were examined in the nucleophilic acyl substitution of acid anhydrides. Among them, [UO2(OPPh3)4]2+ was the most efficient to give ethyl acetate and acetic acid from acetic anhydride (Ac2O) and ethanol, and was resistant towards decomposition during the catalytic reaction. Several nucleophiles were also subjected to the catalytic acylation reaction using acetic and pivalic anhydride. Kinetic and spectroscopic studies suggested that [UO2(OPPh3)4]2+ interacts with Ac2O to form [UO2(Ac2O)(OPPh3)3]2+. Interaction of this actual catalyst with additional Ac2O determines the rate of the overall nucleophilic acyl substitution reaction.
- Takao, Koichiro,Akashi, Shin
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p. 12201 - 12207
(2017/03/08)
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- N-Isocyanimino-Triphenylphosphorane (Ph 3Pnnc) as an Efficient Reagent for the Preparation of Fully Substituted 1,3,4-Oxadiazoles via Intramolecular Aza-Wittig Reaction in Water
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An efficient green protocol for the synthesis of 1,3,4-oxadiazoles derivatives via a one-pot three-component reaction of aromatic carboxylic acids, N-isocyanimino-Triphenylphosphorane and ester derivatives of 2-oxopropyl alcohol (2-oxopropyl benzoate, 2-oxopropyl-4-bromobenzoate and 2-oxopropyl acetate) in water at room temperature have been developed. The present methodology offers several advantages such as a simple procedure, high yields, environmental friendliness and the absence of any volatile and hazardous organic solvents.
- Jafari, Ali,Ramazani, Ali,Asiabi, Pegah Azimzadeh,Sadri, Fariba,Joo, Sang Woo
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p. 2246 - 2254
(2015/12/20)
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- Regioselective hydration of terminal alkynes catalyzed by a neutral gold(I) complex [(IPr)AuCl] and one-pot synthesis of optically active secondary alcohols from terminal alkynes by the combination of [(IPr)AuCl] and Cp?RhCl[(R, R)-TsDPEN]
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A neutral gold(I) complex [(IPr)AuCl] (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) was found to be a highly effective catalyst for the hydration of terminal alkynes, including aromatic alkynes and aliphatic alkynes. The desired methyl ketones were obtained in high yields with complete regioselectivities. Furthermore, a series of optically active secondary alcohols could be obtained in high yield with good to excellent enatioselectivities via one-pot sequential hydration/asymmetric transfer hydrogenation (ATH) from terminal alkynes by the combination of of [(IPr)AuCl] and Cp?RhCl[(R,R)-TsDPEN] (Cp? = pentamethylcyclopentadienyl, TsDPEN = N-(p-toluenesulfonyl)-1,2-diphenylethylenediamine). Notably, this research exhibited the potential of the direct use of neutral gold(I) complexes instead of cationic ones as catalysts for the activation of multiple bonds for organic synthesis.
- Li, Feng,Wang, Nana,Lu, Lei,Zhu, Guangjun
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p. 3538 - 3546
(2015/04/14)
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- The reaction of N-isocyaniminotriphenylphosphorane with ester derivatives of 2-oxopropyl alcohol (2-Oxopropyl 4-Bromobenzoate, 2-Oxopropyl Benzoate, and 2-Oxopropyl Acetate) in the presence of aromatic carboxylic acids: A one-pot efficient three-component reaction for the synthesis of fully substituted 1,3,4-oxadiazole derivatives
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Reactions of N-isocyaniminotriphenylphosphorane with ester derivatives of 2-oxopropyl alcohol (2-oxopropyl 4-bromobenzoate, 2-oxopropyl benzoate, and 2-oxopropyl acetate) in the presence of aromatic carboxylic acids proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions and no side reactions were observed.
- Ramazani, Ali,Ahmadi, Yavar,Karimi, Zahra,Rezaei, Aram
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p. 1447 - 1451
(2013/02/23)
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- A one-pot efficient four-component reaction for the synthesis of 2-(arylamino)-2-(5-aryl-1,3,4-oxadiazol-2-yl)propyl benzoate (or acetate) derivatives
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Reactions of (N-isocyanimino) triphenylphosphorane with 2-oxopropylbenzoate (or acetate) in the presence of aromatic carboxylic acids and primary amines proceed smoothly at room temperature and in neutral conditions to afford sterically congested 1,3,4-oxadiazole derivatives in high yields. The reaction proceeds smoothly and cleanly under mild conditions, and no side reactions were observed.
- Ramazani, Ali,Ahmadi, Yavar,Malekzadeh, Asemeh Mashhadi,Rezaei, Aram
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scheme or table
p. 692 - 698
(2012/01/03)
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- Lead(IV) acetate mediated cleavage of β-hydroxy ethers: Enantioselective synthesis of α-acetoxy carbonyl compounds
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α-Acetoxy aldehydes or α-acetoxy ketones can be efficiently synthesized by treating 2,3-epoxy primary alcohols with lead tetraacetate. The reaction, which proceeds with complete regio- and stereoselectivity facilitates the enantioselective synthesis of α-acetoxy carbonyl compounds from allyl alcohols, via Sharpless epoxidation. Cyclic β-hydroxy ethers, with an oxygenated five-, six- or seven-membered ring, are transformed into α-acetoxy ethers.
- Alvarez-Manzaneda, Enrique,Chahboun, Rachid,Alvarez, Esteban,Alvarez-Manzaneda, Ramón,Mu?oz, Pedro E.,Jimenez, Fermín,Bouanou, Hanane
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experimental part
p. 8910 - 8917
(2011/12/01)
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- Synthesis of a dimethylfuran-containing macrolide insect pheromone
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The synthetic pathway to the furan-containing macrolide pheromone (1) of Galerucella beetles was shortened from 13 steps in the original synthesis to 10 steps, and the overall yield was increased greater than six-fold. A concise Reformatsky-based sequence of reactions was utilized to construct the key precursor, 2,3-dimethyl-2-butenolide. Reduction of the butenolide with diisobutylaluminum hydride afforded 3,4-dimethylfuran. A one-pot sequence of lithiation, alkylation by a tetrahydropyranyl (THP)-containing iodide, a second lithiation, and, finally, formylation gave the required tetrasubstituted furan intermediate, 3,4-dimethyl-5-[5-(tetrahydrofuran-2-yloxy)pentyl]-2-furaldehyde. To continue construction of the three-carbon acyl side chain, the aldehyde was converted to an unsaturated ester by a Horner-Wadsworth-Emmons (HWE) condensation with triethyl phosphonoacetate. After reduction of the double bond in the ester side chain and removal of protective groups, the lactone ring was closed using the Mitsunobu method, which is milder, is simpler, and could be accomplished with less solvent than the previous (Yamaguchi) method.
- Petroski, Richard J.,Bartelt, Robert J.,Vermillion, Karl
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experimental part
p. 1389 - 1405
(2009/09/26)
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- Low pressure carbonylation of heterocycles
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Heterocycles, e.g., epoxides, are carbonylated at low pressure with high percentage conversion to cyclic, ring expanded products using the catalyst where L is tetrahydrofuran (THF).
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Page/Page column 4
(2008/06/13)
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- Practical β-lactone synthesis: Epoxide carbonylation at 1 atm
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A readily prepared bimetallic catalyst is capable of effecting epoxide carbonylation to produce β-lactones at substantially lower CO pressures than previously reported catalyst systems. A functionally diverse array of β-lactones is produced in excellent yields at CO pressures as low as 1 atm. This procedure allows for epoxide carbonylation on a multigram scale without the requirement of specialized, high-pressure equipment.
- Kramer, John W.,Lobkovsky, Emil B.,Coates, Geoffrey W.
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p. 3709 - 3712
(2007/10/03)
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- Chemo-enzymatic preparation of hydroxymethyl ketones
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A series of hydroxymethyl ketones 4a-g were obtained from the corresponding halogenomethyl ketones 2a-g via their transformation into acetoxymethyl ketones 3a-g by 18-crown-6 catalysed substitution with NaOAc followed by Novozyme 435 catalysed ethanolysis. This convenient chemo-enzymatic route provides a mild, heavy-metal-free alternative to the direct α-hydroxylations of methyl ketones 1a-g.
- Paizs, Csaba,Tosa, Monica,Majdik, Cornelia,Bodai, Viktoria,Novak, Lajos,Irimie, Florin-Dan,Poppe, Laszlo
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p. 2400 - 2402
(2007/10/03)
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- FTIR spectroscopic study of the OH-induced oxidation of two linear acetates: Ethyl and n-propyl acetates
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OH-induced oxidation mechanisms of ethyl and n-propyl acetates have been investigated at room temperature (298 ± 5 K) and atmospheric pressure by photolysing CH3ONO/acetate/NO mixtures with FTIR spectroscopy as analytical device. The main oxidation products and their yields were as follows: from ethyl acetate, acetic acid (0.75 ± 0.13), acetoxyacetaldehyde (0.15 ± 0.05), acetic anhydride (0.02 ± 0.01), formic acetic anhydride (0.02 ± 0.01) and peroxyacetyl nitrate (PAN); from n-propyl acetate, acetoxyacetaldehyde (0.22 ± 0.06), formic acetic anhydride (0.28 ± 0.03), acetic acid (0.15 ± 0.02), acetaldehyde (0.35 ± 0.10), peroxypropionyl nitrate (PPN) and probably acetoxypropionaldehyde (0.30 ± 0.10). From these data, oxidation schemes of these two acetates were elucidated. This study reveals in particular the specifc reactivity of acetates by confirming the novel α-ester rearrangement proposed recently by Tuazon et al. (J. Phys. Chem. A, 1998, 102, 2316) and then by showing that oxygenated alkoxyl radicals may not follow the same rules of reactivity as other alkoxyl radicals. This last observation shows the necessity for further experiments to understand the influence of the oxygenated function on alkoxyl reactivity.
- Picquet-Varrault,Doussin,Durand-Jolibois,Carlier
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p. 2595 - 2606
(2007/10/03)
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- The kinetic regularities, products, and mechanism of the thermal decomposition of dimethyldioxirane. The contribution of molecular and radical reaction channels
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The products and kinetics of the thermal decomposition of dimethyldioxirane (DMDO) were studied. The reaction proceeds via three parallel pathways: isomerization to methyl acetate, oxygen atom insertion into the C - H bond of a solvent molecule (acetone), and the solvent-induced homolysis of the O - O bond in the DMDO molecule. The contribution of the latter reaction channel is ca. 23% at 56 °C. The overall kinetic parameters of DMDO thermolysis in oxygen atmosphere were determined. The free radical-induced DMDO decomposition occurs in an inert atmosphere. The formal kinetics of this reaction was investigated. The mechanism of the DMDO thermolysis is discussed.
- Khursan,Grabovskii,Kabal'nova,Galkin,Shereshovets
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p. 1338 - 1348
(2007/10/03)
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- Fine particulate matter (PM) and organic speciation of fireplace emissions
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This paper presents a summary of fireplace particle size and organic speciation data gathered to date in an ongoing project. Tests are being conducted in a residential wood combustion (RWC) laboratory on three factory- built fireplaces. RWC wood smoke particles 10 μm (PM10) consist primarily of a mixture of organic compounds that have condensed into droplets; therefore, the size distribution and total mass are influenced by temperature of the sample during its collection. During the series 1 tests (15 tests), the dilution tunnel used to cool and dilute the stack gases gave an average mixed gas temperature of 47.3 °C and an average dilution ratio of 4.3. Averages for the PM2.5 (particles 2.5 μm) and PM10 fractions were 74 and 84%, respectively. For the series 2 tests, the dilution tunnel was modified, reducing the average mixed gas temperatures to 33.8 °C and increasing the average dilution ratio to 11.0 in tests completed to date. PM2.5 and PM10 fractions were 83 and 91%, respectively. Since typical winter time mixed gas temperatures would usually be less than 10 °C, these size fraction results (even from the series 2 tests) probably represent the lower bound; the PM10 and PM2.5 size fractions might be higher at typical winter temperatures. The particles collected on the first stage (cutpoint ? 11.7 μm) were light gray and appeared to include inorganic ash. Particles collected on the remainder of the stages were black and appeared to be condensed organics because there was noticeable lateral bleeding of the collected materials into the filter substrate. Total particulate emission rates ranged from 10.3 to 58.4 g/h; corresponding emission factors ranged from 3.3 to 14.9 g/kg of dry wood burned. A wide range of Environmental Protection Agency (EPA) Method 8270 semivolatile organic compounds were found in the emissions; of the 17 target compounds quantified, major constituents are phenol, 2-methylphenol, 4- methylphenol, 2,4-dimethylphenol, and naphthalene. An account is given on fireplace particle size and organic speciation data gathered to date in an ongoing project. Total particulate matter emission rates and the results of analyses for semivolatile organics in the emissions are discussed.
- Purvis, Carol R.,Mccrillis, Robert C.,Kariher, Peter H.
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p. 1653 - 1658
(2007/10/03)
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- Molecule-Induced Homolysis versus "Concerted Oxenoid Oxygen Insertion" in the Oxidation of Organic Compounds by Dimethyldioxirane
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Evidence for a molecule-induced homolysis of dimethyldioxirane by several classes of organic compounds (alkanes, alkenes, ethers, alcohols, aldehydes, iododerivatives) is reported. Carbon-centered radicals, arising from alkanes, ethers, and aldehydes, are trapped by CBrCl3 or protonated quinolines. The dramatic influence of oxygen in these reactions, as well as the formation of products of induced homolysis of the dioxirane by carbon-centered radicals (CH4, CH3OH, CH3COOCH3, ROCOCH3, CH3COOCH2COCH3), strongly supports a radical mechanism. With alkenes and iodo derivatives the induced homolysis would lead to diradical intermediates, whose very fast fragmentation would prevent detection, but circumstantial evidence supports a radical mechanism.
- Bravo, Anna,Fontana, Francesca,Fronza, Giovanni,Minisci, Francesco,Zhao, Lihua
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p. 254 - 263
(2007/10/03)
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- Chemistry of C-2 glyceryl radicals: Indications for a new mechanism of lipid damage
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Precursors for the selective generation of C-2 glyceryl radicals were synthesized, and the chemical behavior of the corresponding radicals was investigated by ESR spectroscopy, product analysis, and kinetic measurements. It was found that cleavage of the β-C,O bond proceeds rapidly, if a hydroxyl group is present at the radical carbon center. The rate constant for the elimination of a β-acetoxy group from radical 30 was dependent on the solvent (k(E) = 4 x 105 s-1 in methanol, k(E) = 2 x 107 s-1 in toluene). With these results and ab initio calculations a concerted elimination mechanism is suggested. α-Methoxy-substituted C-2 glyceryl radicals 42 and 43 showed heterolytic β-C,O bond cleavage under formation of radical cations. With ester-substituted radicals 24 and 35 no elimination could be observed. To demonstrate the biological significance of these findings, C-2 lysolecithin radical 53 was generated, which led to fast β-elimination.
- Müller, Stephan N.,Batra, Rohit,Senn, Martin,Giese, Bernd,Kisel, Micail,Shadyro, Oleg
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p. 2795 - 2803
(2007/10/03)
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- On the triggering of free radical reactivity of dimethyldioxirane
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Performing the reaction in the presence of CCl3Br, and/or in inert gas atmosphere, dramatically changes the reation kinetics, rate-law and product distribution of adamantane oxyfunctionalization by dimethyldioxirane (1a). The kinetics of decomposition of the dioxirane is also markedly influenced by the addition of CCl3Br and by depletion of O2 gas. The data suggest that these conditions can trigger dioxirane radical reactions; these are widely different from the straightforward, highly selective concerted O-insertion into C-H bonds which would take place in the absence of CCl3Br and of conditions inducing radical reactivity.
- Curci, Ruggero,Dinoi, Anna,Fusco, Caterina,Lillo, Maria A.
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p. 249 - 252
(2007/10/02)
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- Induced Homolysis of Dimethyldioxirane by Alkanes and Alkyl Radicals in Oxidation Processes. The Dramatic Role of Molecular Oxygen and Radical Inhibitors
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The oxidation of alkanes by dimethyldioxirane is dramatically affected by the presence of molecular oxygen and radical inhibitors, supporting the hypothesis of a free-radical mechanism for these extraordinarily selective reactions; the factors affecting the free-radical selectivity are suggested.
- Bravo, Anna,Fontana, Francesca,Fronza, Giovanni,Mele, Andrea,Minisci, Francesco
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p. 1573 - 1574
(2007/10/02)
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- Oxidation of alkyl and aryl iodides, phenylacetaldehyde and alkenes by dimethyldioxirane. Reaction products and mechanism
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Alkyl and aryl iodides are smoothly oxidized to iodosoderivatives and phenylacetaldehyde is oxidized to phenylacetic acid or benzyl acetate by dimethyldioxirane depending on the presence or not of oxygen. These results and the epoxidation or the allylic oxidation of alkenes by the same reagent are explained by a general free-radical mechanism.
- Bravo, Anna,Fontana, Francesca,Fronza, Giovanni,Minisci, Francesco,Serri, Anna
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p. 6945 - 6948
(2007/10/02)
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- Asymmetric Reduction of 1-Acetoxy-2-alkanones with Baker's Yeast: Purification and Characterization of α-Acetoxy Ketone Reductase
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An α-acetoxy ketone reducing enzyme has been purified and characterized from the cell-free extract of bakers' yeast (Saccharomyces cerevisiae). Only one NADPH-dependent dehydrogenase that catalyzed the reduction of α-acetoxy ketone was found in bakers' yeast. The molecular weight of the enzyme was estimated to be 36 kDa by SDS-polyacrylamide gel electrophoresis. The enzyme was composed of a single polypeptide chain. The enzyme had reducing activity for both aliphatic and aromatic α-acetoxy ketones, although no reducing activity toward α-chloro ketones and α-hydroxy ketones was found. The enzyme catalyzed the reduction of not only α-acetoxy ketones, but also β-keto esters. Studies on the chromatographic behavior and stereospecificity indicated that the enzyme was identical with one of the β-keto ester reductases purified from bakers' yeast.
- Ishihara, Kohji,Nakajima, Nobuyoshi,Tsuboi, Sadao,Utaka, Masanori
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p. 3314 - 3319
(2007/10/02)
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- Chemistry of Dioxiranes. 21. Thermal Reactions of Dioxiranes
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Thermolysis of dioxiranes in solutions of their parent ketones or in mixtures of the parent ketone and a foreign ketone leads to the formation of esters.The results are explained by postulating a free-radical mechanism involving H atom abstraction from the ketones.The resulting radicals are converted to the observed esters by reaction with acyloxy radicals derived from homolysis of the dioxiranes.Autodecomposition of dimethyldioxirane in acetone solution at room temperature gives methyl acetate at a very slow rate.When catalyzed by BF3 etherate the same decomposition proceeds much more rapidly and is accompanied by acetol formation.
- Singh, Megh,Murray, Robert W.
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p. 4263 - 4270
(2007/10/02)
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- Palladium(II)-catalyzed acetalization of allylic acetates and its utilization for the synthesis of 2-cyanovinyl ketones
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α-Cyanoallyl acetate (1 a), when treated with methanol in the presence of bis(acetonitrile)dichloropalladium(II) catalyst, is acetalized at the terminal olefinic carbon to give 1-cyano-3,3-dimethoxypropyl acetate (2). γ-Substituted α-cyanoallyl acetates give 3-substituted 1-cyano-3-oxo-propyl acetates 5 from which 2-cyanovinyl ketones 11 are obtained in good yields.
- Hosokawa,Aoki,Murahashi
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p. 558 - 561
(2007/10/02)
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- Ozonolyses of Olefins with Chloro Substituents in Vinylic Positions on Polyethylene
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Ozonolyses of the chloro-substituted 5- and 6-membered cycloolefins 20a, 20b and 30a-c on polyethylene afforded the corresponding chloro-substituted ozonides.The thermal decomposition of these ozonides is described.Ozonolyses of the same olefins in solution and of the acyclic chloro olefins 5 and 8 both on polyethylene and in solution gave no ozonides.
- Griesbaum, Karl,Greinert, Reinhard
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p. 391 - 397
(2007/10/02)
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- Reactions of Thallium(III) Carboxylates with Ketones
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In the reaction of ketones RCOCH3 (R = CH3, C2H5, n-C3H7, i-C3H7, n-C4H9, i-C4H9, tert-C4H9) with thallium(III) acetate in methanol, thallation at CH3 or at α-C in R has been observed by NMR spectroscopy.J(203/205Tl-1H) in RCOCH2X is nearly independent of R (ca. 1290 Hz), but in R'CHXCOCH3 (R' = H, CH3, C2H5) it increases with increasing chain length.RCOCH2X and R'CHXCOCH3 decompose to give the corresponding acetoxylated ketones, e.g.CH3COCH2OCOCH3.Analogous thallation products have been observed in the reaction of acetone and C2H5COCH3 with thallium(III) iso-butyrate. - Keywords: Thallation, Ketones, Thallium(III) Acetate, Thallium(III) iso-Butyrate
- Vollmerhaus, Mechthild,Huber, Friedo
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p. 141 - 143
(2007/10/02)
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