- Influence of heterogenization on catalytic behavior of mono- and bimetallic nanoparticles formed in poly(styrene)-block-poly(4-vinylpyridine) micelles
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Influence of heterogenization on catalytic properties of block copolymer micellar catalysts derived from polystyrene-block-poly-4-vinylpyridine and containing Pd monometallic and bimetallic PdAu, PdPt, and PdZn nanoparticles has been studied in selective hydrogenation of the triple bond of 3,7-dimethyloctaen-6-yne-1-ol-3 (dehydrolinalool). We demonstrate that the heterogenization can both increase and decrease catalytic activity depending on the type of NPs. In the absence of a modifying metal (Pd monometallic nanoparticles) or for PdZn nanoparticles where Zn is the electron donor, the activity of heterogenized catalysts increases, while for PdAu and PdPt based catalysts, where the modifying metal is the electron acceptor, the activity decreases. These changes are explained by the increased polarity of the catalyst after deposition on alumina (addition of a component with a higher dielectric constant) offset by poor accessibility of some catalytic sites of nanoparticles containing electron deficient Pd atoms.
- Sulman, Esther M.,Matveeva, Valentina G.,Sulman, Mikhail G.,Demidenko, Galina N.,Valetsky, Pyotr M.,Stein, Barry,Mates, Tom,Bronstein, Lyudmila M.
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Read Online
- Evidence of an equilibrium between selenides and osmium(VIII) reagents and selenoxides and osmium(VI) reagents
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Driving the equilibrium between selenides and osmium(VIII) reagents with selenoxides and osmium(VI) by a subsequent reaction (rearrangement of allyl selenoxides to allyl alcohols or addition of osmium(VIII) species on C=C double bonds) to one side, allows the transformation of methyl geranyl selenides to linalool and of methyl citronellyl selenoxide to 6,7-dihydroxy citronellyl selenide.
- Krief, Alain,Destree, Alexandra,Durisotti, Virginie,Moreau, Nicolas,Smal, Caroline,Colaux-Castillo, Catherine
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Read Online
- Structure and Properties of Bimetallic Colloids Formed in Polystyrene-block-Poly-4-vinylpyridine Micelles: Catalytic Behavior in Selective Hydrogenation of Dehydrolinalool
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Catalytic properties of palladium and bimetallic (PdAu, PdPt, and PdZn) nanoparticles formed in block copolymer micelles derived from polystyrene-block-poly-4-vinylpyridine (PS-b-P4VP) were studied in dehydrolinalool (DHL) hydrogenation. FTIR spectroscopy on CO adsorption and XPS show that the second metal (Au, Pt, or Zn) acts as a modifier toward Pd, changing both its electronic structure and its surface geometry. In turn, this change provides higher catalytic activity of bimetallic particles formed in PS-b-P4VP micelles compared to Pd micelles, which can be ascribed mainly to an increase in the number of active centers on the particle surface. High selectivity of DHL hydrogenation (99.8% at 100% conversion) was achieved for all the Pd and bimetallic micellar catalysts, by chemical modification of the nanoparticle surface with pyridine units. Kinetic study of DHL hydrogenation, along with computational kinetic models, allowed us to describe a hydrogenation mechanism with these catalysts.
- Bronstein, Lyudmila M.,Chernyshov, Dmitrii M.,Volkov, Ilya O.,Ezernitskaya, Marina G.,Valetsky, Peter M.,Matveeva, Valentina G.,Sulman, Esther M.
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Read Online
- Method for efficiently preparing enol through selective hydrogenation of alkynol
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The invention provides a method for efficiently preparing enol through selective hydrogenation of alkynol. A conventional tank reactor and a micro-channel reactor are combined for use, and the micro-channel reactor can be used for quickly preparing an enol product after immobilizing a rare earth metal doped catalyst, so that the reaction time is shortened, and the production efficiency is improved. And a phosphine compound is added as a side reaction inhibitor to improve the selectivity.
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Paragraph 0052-0061
(2021/03/24)
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- Method for preparing allyl alcohol compound by reduction of propargyl alcohol compound
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A hydrazide compound is used as a reducing agent, an organic amine is used as an auxiliary, and the propargyl alcohol compound is selectively reduced to obtain an allyl alcohol compound under the presence of a solvent and a certain temperature. The method does not need Pd catalyst which is expensive, and the reducing agent and auxiliary agent are cheap and easily available, easy to separate, free of residue in the product, simple in reaction operation process, mild in reaction condition, high in target product selectivity and the like.
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Paragraph 0059-0060
(2021/11/10)
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- Divergent Total Syntheses of Yaequinolone-Related Natural Products by Late-Stage C-H Olefination
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Divergent total syntheses of 10 yaequinolone-related natural products have been achieved for the first time by late-stage C-H olefination of 3,4-dioxygenated 4-aryl-5-hydroxyquinolin-2(1H)-ones, core structures of this family of natural products. A robust synthetic methodology to construct the core structures has been established, and the C-H olefination reaction has been carried out with synthetically useful yields and high levels of site-selectivity under mild reaction conditions in the presence of a Pd/S,O-ligand catalyst.
- Ces, Sabela Vega,Fernández-Ibá?ez, M. ángeles,Jia, Wen-Liang
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supporting information
p. 6259 - 6277
(2021/05/29)
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- SELECTIVE HYDROGENATION OF ALKYNOLS TO ALKENOLS IN THE PRESENCE OF A PHOSPHORUS COMPOUND
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The present invention relates to a process of hydrogenating an aIkynoI selectively to an alkenol by hydrogen using a hydrogenation catalyst which is palladium supported on a carrier in the presence of an additive which is an organic phosphorus compound bearing either a phosphine or a phosphine oxide group and with the proviso that if the additive bears a phosphino group that the additive bears two or more phosphino groups.
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Page/Page column 16
(2020/12/11)
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- Hydroxypyridine ligand and preparation method and catalytic application thereof (by machine translation)
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The invention provides a hydroxypyridine ligand, a preparation method thereof and application, for catalyzing allyl alcohol isomerism, wherein the structural formula of the hydroxypyridine ligand is as follows : One or more, R wherein, R represents the substituent C1 - C20 selected from, alkyl, phenyl, naphthyl, heteroaryl, methoxy, fluoro, chloro, bromo, trifluoromethyl, methoxycarbonyl, amine has a higher catalytic activity, than that of a ligand 2 - such as an amine alcohol α, ω - hydroxyquinoline reported in the known literature and having a double-tooth chelating effect, and a metal tungsten bonding capability. The present invention provides, a; ligand 1,3 - and a, dihalide coupling, which can be rapidly, efficiently obtained . The, ligand has, a higher catalytic activity than the, metal tungsten bonding capability. (by machine translation)
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Paragraph 0080-0082
(2020/05/11)
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- Method for preparing linalool
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The invention provides a method for preparing linalool. The method specifically comprises the following steps: taking 6-methyl-5-heptene-2 one as a raw material, carrying out ethynylation reaction toprepare dehydrolinalool, removing water in a reaction system, carrying out conventional distillation or rectification for separating dehydrolinalool, and carrying out selective hydrogenation to synthesize linalool. Impurities with the molecular weight of 170 (M = 170) can be generated in the treatment process of the 6-methyl-5-heptene-2 one ethynylation reaction liquid, and the content of the impurities should be strictly controlled to be 0.01% or below in order to regulate and control the final product linalool aroma. In order to control the content of the impurity, the generation of the impurity can be optimized and inhibited in the aspect of a post-treatment mode of a 6-methyl-5-heptene-2 one acetylation reaction solution, or the impurity is removed by adopting an efficient rectification mode.
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Paragraph 0030; 0035-0039; 0044-0048; 0051-0053
(2020/05/01)
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- A methyl Heptenone synthetic Linalool method
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This invention discloses a methyl Heptenone efficient synthesis of the Linalool method, the method comprises: vinyl Grignard reagent in under the action of a Lewis acid catalyst, high selectivity to methyl Heptenone carbonyl addition, one-step reaction to obtain the target product Linalool. The major advantage of this invention is the use of the Lewis acid, vinyl Grignard reagent to improve the selectivity of the carbonyl, reduce the occurrence of side reactions, effectively improves the reaction yield, can be as high as 96% or more; secondly, compared with the present commonly used acetylene hydrogenation law - part, the method of mild reaction conditions, without the need of high-voltage equipment, without the need of using odor of ammonia, the resulting product fragrance is pure, more close to the natural Linalool, can bring about relatively good economic benefits.
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Paragraph 0043; 0044
(2019/05/15)
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- Synergic actions of BEA-type zeolites and ultrasonic irradiation in conversion of geraniol
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The geraniol conversion reaction was initiated by the simultaneous action of micro- and micro-mesoporous BEA-type zeolites and ultrasonic irradiation (UMR-300B hybrid reactor, 25 kHz, 100-900 W; SRF-1, 20-60 kHz, 100 W). Geraniol by ultrasonic irradiation at 27-100 °C, had a low degree of conversion, upto 2 %. Geraniol was a resistant to ultrasound in argon atmosphere solutions of N,Ndimethylformamide and methanol. In methanolic solution, geraniol was actively converted to linalool and to methyl ethers of linalool and nerol with the selectivity of 80 % on zeolite BEA-25 under ultrasonic irradiation in air at 30 °C. Using BEA-type zeolite/ultrasonicassisted reaction was increased the degree of conversion of geraniol, the selectivity and yield to linalool and nerol on the most active RBEA-25 zeolite by prolonged ultrasonic irradiation (1.5-5 h) or under combined ultrasound and microwave irradiation (US 300 W/MW 550 W, 1.5 h, 80 °C).
- Ramishvili, Ts.,Tsitsishvili,Ivanova,Kokiashvili,Bukia,Kurtsikidze
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p. 438 - 444
(2019/01/14)
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- Mild alkaline hydrolysis of hindered esters in non-aqueous solution
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Sterically hindered esters of carboxylic acids, which are considered very resistant to saponification, were rapidly and efficiently saponified in a non-aqueous medium using NaOH in MeOH/CH2Cl2 (1:9) at room temperature. Furthermore, this reaction protocol was extended and successfully applied to the hydrolysis of tosylates and N-tosyl indoles.
- Theodorou, Vassiliki,Alagiannis, Michalis,Ntemou, Nikoleta,Brentas, Alexios,Voulgari, Pinelopi,Polychronidou, Vasiliki,Gogou, Marina,Giannelos, Marios,Skobridis, Konstantinos
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p. 308 - 319
(2018/11/26)
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- Structural and functional insights into asymmetric enzymatic dehydration of alkenols
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The asymmetric dehydration of alcohols is an important process for the direct synthesis of alkenes. We report the structure and substrate specificity of the bifunctional linalool dehydratase isomerase (LinD) from the bacterium Castellaniella defragrans that catalyzes in nature the hydration of β-myrcene to linalool and the subsequent isomerization to geraniol. Enzymatic kinetic resolutions of truncated and elongated aromatic and aliphatic tertiary alcohols (C5-C15) that contain a specific signature motif demonstrate the broad substrate specificity of LinD. The three-dimensional structure of LinD from Castellaniella defragrans revealed a pentamer with active sites at the protomer interfaces. Furthermore, the structure of LinD in complex with the product geraniol provides initial mechanistic insights into this bifunctional enzyme. Site-directed mutagenesis confirmed active site amino acid residues essential for its dehydration and isomerization activity. These structural and mechanistic insights facilitate the development of hydrating catalysts, enriching the toolbox for novel bond-forming biocatalysis.
- Nestl, Bettina M.,Geinitz, Christopher,Popa, Stephanie,Rizek, Sari,Haselbeck, Robert J.,Stephen, Rosary,Noble, Michael A.,Fischer, Max-Philipp,Ralph, Erik C.,Hau, Hoi Ting,Man, Henry,Omar, Muhiadin,Turkenburg, Johan P,Van Dien, Stephen,Culler, Stephanie J.,Grogan, Gideon,Hauer, Bernhard
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p. 275 - 281
(2017/02/23)
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- Terpene Cyclizations inside a Supramolecular Catalyst: Leaving-Group-Controlled Product Selectivity and Mechanistic Studies
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The tail-to-head terpene cyclization is arguably one of the most complex reactions found in nature. The hydrogen-bond-based resorcinarene capsule represents the first man-made enzyme-like catalyst that is capable of catalyzing this reaction. Based on noncovalent interactions between the capsule and the substrate, the product selectivity can be tuned by using different leaving groups. A detailed mechanistic investigation was performed to elucidate the reaction mechanism. For the cyclization of geranyl acetate, it was found that the cleavage of the leaving group is the rate-determining step. Furthermore, the studies revealed that trace amounts of acid are required as cocatalyst. A series of control experiments demonstrate that a synergistic interplay between the supramolecular capsule and the acid traces is required for catalytic activity.
- Zhang, Qi,Catti, Lorenzo,Pleiss, Jürgen,Tiefenbacher, Konrad
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supporting information
p. 11482 - 11492
(2017/08/30)
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- Method for continuously preparing linalool from allylic alcohol by isomerization process
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The invention provides a method for continuously preparing linalool from allylic alcohol by an isomerization process. The method comprises the following steps: preparing a vanadium-amine complex catalyst, adding a reacting product and a catalyst, controlling isomerization reaction conditions, constantly adding the reacting product, and constantly rectifying, wherein the vanadium-amine complex catalyst is prepared by adding 1 part by weight of xylene, 0.01-0.1 part by weight of a vanadium compound and 0.01-0.1 part by weight of nitrogen base, starting to stir and heat, insulating for 1-3 hours at 140 DEG C, cooling to below 50 DEG C, and filtering to reclaim the catalyst. According to the method, the catalyst system has high reaction selectivity, the selectivity of linalool is 93.2-96.2 percent, the yield of linalool is 92.7-94.5 percent, the scrap rate is 2.7-4.0 percent, and the linalool content is 98.5-98.7 percent. The catalyst has low unit consumption.
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Paragraph 0026; 0027; 0028; 0029; 0030; 0031
(2016/11/24)
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- One-step Synthesis of Core-Gold/Shell-Ceria Nanomaterial and Its Catalysis for Highly Selective Semihydrogenation of Alkynes
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We report a facile synthesis of new core-Au/shell-CeO2 nanoparticles (Au@CeO2) using a redox-coprecipitation method, where the Au nanoparticles and the nanoporous shell of CeO2 are simultaneously formed in one step. The Au@CeO2 catalyst enables the highly selective semihydrogenation of various alkynes at ambient temperature under additive-free conditions. The core-shell structure plays a crucial role in providing the excellent selectivity for alkenes through the selective dissociation of H2 in a heterolytic manner by maximizing interfacial sites between the core-Au and the shell-CeO2.
- Mitsudome, Takato,Yamamoto, Masaaki,Maeno, Zen,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 13452 - 13455
(2015/11/10)
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- Isotope sensitive branching and kinetic isotope effects to analyse multiproduct terpenoid synthases from Zea mays
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Multiproduct terpene synthases TPS4-B73 and TPS5-Delprim from Zea mays exhibit isotopically sensitive branching in the formation of mono- and sesquiterpene volatiles. The impact of the kinetic isotope effects and the stabilization of the reactive intermediates by hyperconjugation along with the shift of products from alkenes to alcohols are discussed.
- Gatto, Nathalie,Vattekkatte, Abith,K?llner, Tobias,Degenhardt, J?rg,Gershenzon, Jonathan,Boland, Wilhelm
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supporting information
p. 3797 - 3800
(2015/03/30)
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- A domain swapping approach to elucidate differential regiospecific hydroxylation by geraniol and linalool synthases from perilla
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Geraniol and linalool are acyclic monoterpenes found in plant essential oils that have attracted much attention for their commercial use and in pharmaceutical studies. They are synthesized from geranyl diphosphate (GDP) by geraniol and linalool synthases, respectively. Both synthases are very similar at the amino acid level and share the same substrate; however, the position of the GDP to which they introduce hydroxyl groups is different. In this study, the mechanisms underlying the regiospecific hydroxylation of geraniol and linalool synthases were investigated using a domain swapping approach and sitedirected mutagenesis in perilla. Sequences of the synthases were divided into ten domains (domains I to IV-4), and each corresponding domain was exchanged between both enzymes. It was shown that different regions were important for the formation of geraniol and linalool, namely, domains IV-1 and -4 for geraniol, and domains III-b, III-d, and IV-4 for linalool. These results suggested that the conformation of carbocation intermediates and their electron localization were seemingly to be different between geraniol and linalool synthases. Further, five amino acids in domain IV-4 were apparently indispensable for the formation of geraniol and linalool. According to three-dimensional structural models of the synthases, these five residues seemed to be responsible for the different spatial arrangement of the amino acid at H524 in the case of geraniol synthase, while N526 is the corresponding residue in linalool synthase. These results suggested that the side-chains of these five amino acids, in combination with several relevant domains, localized the positive charge in the carbocation intermediate to determine the position of the introduced hydroxyl group.
- Sato-Masumoto, Naoko,Ito, Michiho
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- Characterization of a novel hormone-sensitive lipase family esterase from Rhizomucor miehei with tertiary alcohol hydrolysis activity
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A novel esterase gene (designated RmEstB) from the thermophilic fungus Rhizomucor miehei was cloned and functionally expressed in Escherichia coli. Sequence analysis revealed a 960-bp open reading frame encoding a protein of 319 amino acids. The deduced protein sequence contained an HGGG motif, suggesting that the enzyme is a hormone-sensitive lipase (HSL) family esterase. It showed highest identity of 52% with the esterase from Pseudomonas mandelii. The recombinant esterase was purified to homogeneity at 5.1-fold purification with a recovery yield of 85%. The molecular mass of RmEstB was estimated to be 37 kDa by SDS-PAGE. RmEstB was most active at pH 7.5 and 50 °C. The enzyme was highly stable in the presence of 30% ethanol, methanol, acetone, isopropanol, dimethyl sulfoxide and acetonitrile. RmEstB showed a broad range of substrate specificities toward various p-nitrophenol (pNP) esters (C2-C10) and triglycerides (C2-C6), with the highest specific activities obtained for pNP acetate (255 U/mg) and triacetin (1330 U/mg), respectively. In addition, RmEstB efficiently catalyzed the hydrolysis of sterically hindered esters of tertiary alcohols. This study presents a novel fungal HSL family esterase with potential for some industrial applications.
- Yan, Qiao-Juan,Yang, Shao-Qing,Duan, Xiao-Jie,Xu, Hai-Bo,Liu, Yu,Jiang, Zheng-Qiang
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- Thermal behavior of pinan-2-ol and linalool
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Linalool is an important intermediate for syntheses of isoprenoid fragrance compounds and vitamins A and E. One process option for its production is the thermal gas-phase isomerization of cis- and trans-pinan-2-ol. Investigations of this reaction were performed in a flow-type apparatus in a temperature range from 350-600 °C and a residence time range of 0.6-0.8 s. Rearrangement of the bicyclic alcohol led to linalool, plinols arising from consecutive reactions of linalool and other side products. Effects of residence time, temperature, surface-to-volume-ratio, carrier gas, and the presence of additives on yield and selectivity were studied. Furthermore, the effects of such parameters on ene-cyclization of linalool affording plinols were investigated. Results indicate that manipulation of the reaction in order to affect selectivity is difficult due to the large free path length to other molecules in the gas phase. However, conditions have been identified allowing one to increase the selectivity and the yield of linalool throughout pyrolysis of pinan-2-ol.
- Leiner, Janne,Stolle, Achim,Ondruschka, Bernd,Netscher, Thomas,Bonrath, Werner
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p. 8358 - 8375
(2013/08/23)
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- Novel route to a fruitful mixture of terpene fragrances in particular phellandrene starting from natural feedstock geraniol using weak acidic boron based catalyst
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Myrcene, ocimene and in particular phellandrene were selectively generated as products by dehydration of the natural feedstock geraniol over a weak acidic boron pentasil zeolite catalyst in a gas phase reaction. Additionally linalool was formed by rearrangement reaction. The total selectivity of these 4 terpenes is up to 99%.
- Eisenacher, Matthias,Beschnitt, Stefan,H?lderich, Wolfgang
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experimental part
p. 214 - 217
(2012/09/08)
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- Linalool dehydratase-isomerase, a bifunctional enzyme in the anaerobic degradation of monoterpenes
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Castellaniella (ex Alcaligenes) defragrans strain 65Phen mineralizes monoterpenes in the absence of oxygen. Soluble cell extracts anaerobically catalyzed the isomerization of geraniol to linalool and the dehydration of linalool to myrcene. The linalool dehydratase was present in cells grown on monoterpenes, but not if grown on acetate. We purified the novel enzyme ~1800-fold to complete homogeneity. The native enzyme had a molecular mass of 160 kDa. Denaturing gel electrophoresis revealed one single protein band with a molecular mass of 40 kDa, which indicated a homotetramer as native conformation. The aerobically purified enzyme was anaerobically activated in the presence of 2 mM DTT. The linalool dehydratase catalyzed in vitro two reactions in both directions depending on the thermodynamic driving forces: a water secession from the tertiary alcohol linalool to the corresponding acyclic monoterpene myrcene and an isomerization of the primary allylalcohol geraniol in its stereoisomer linalool. The specific activities (Vmax) were 140 nanokatals mg-1 for the linalool dehydratase and 410 nanokatals mg-1 for the geraniol isomerase, with apparent Km values of 750 μM and 500 μM, respectively. The corresponding open reading frame was identified and revealed a precursor protein with a signal peptide for a periplasmatic location. The amino acid sequence did not affiliate with any described enzymes. We suggest naming the enzyme linalool dehydratase-isomerase according to its bifunctionality and placing it as a member of a new protein family within the hydrolyases (EC 4.2.1.X).
- Brodkorb, Danny,Gottschall, Matthias,Marmulla, Robert,Lueddeke, Frauke,Harder, Jens
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experimental part
p. 30436 - 30442
(2011/11/12)
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- Sesquiterpene synthases Cop4 and Cop6 from Coprinus cinereus: Catalytic promiscuity and cyclization of farnesyl pyrophosphate geometric isomers
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Sesquiterpene synthases catalyze with different catalytic fidelity the cyclization of farnesyl pyrophosphate (FPP) into hundreds of known compounds with diverse structures and stereochemistries. Two sesquiterpene synthases, Cop4 and Cop6, were previously isolated from Coprinus cinereus as part of a fungal genome survey. This study investigates the reaction mechanism and catalytic fidelity of the two enzymes. Cyclization of all-trans-FPP ((E,E)-FPP) was compared to the cyclization of the cis-trans isomer of FPP ((Z,E)-FPP) as a surrogate for the secondary cisoid neryl cation intermediate generated by sesquiterpene synthases, which are capable of isomerizing the C2-C3 π bond of all-trans-FPP. Cop6 is a "high-fidelity" α-cuprenene synthase that retains its fidelity under various conditions tested. Cop4 is a catalytically promiscuous enzyme that cyclizes (E,E)-FPP into multiple products, including (-)-germacrene D and cubebol. Changing the pH of the reaction drastically alters the fidelity of Cop4 and makes it a highly selective enzyme. Cyclization of (Z,E)-FPP by Cop4 and Cop6 yields products that are very different from those obtained with (E,E)-FPP. Conversion of (E,E)-FPP proceeds via a (6R)-β-bisabolyl carbocation in the case of Cop6 and an (E,E)-germacradienyl carbocation in the case of Cop4. However, (Z,E)-FPP is cyclized via a (6S)-β-bisabolene carbocation by both enzymes. Structural modeling suggests that differences in the active site and the loop that covers the active site of the two enzymes might explain their different catalytic fidelities.
- Lopez-Gallego, Fernando,Agger, Sean A.,Abate-Pella, Daniel,Distefano, Mark D.,Schmidt-Dannert, Claudia
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scheme or table
p. 1093 - 1106
(2011/03/20)
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- NEW REACTION WITH PRIMARY ALLYLIC ALCOHOLS
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The invention relates to a process of reacting a primary allylic alcohol with a compound containing a) a metal selected from the group consisting of Ag, Au, Ce, Mn, Ni, Ru, Re, Zn and Co preferably Ag and b) an oxidant like TEMPO (2,2',6,6'-tetra-methylpiperidin- 1-oxyl) or its derivates and c) a co-oxidants selected from the group of peroxodisulfates (PDS), H2SO5, H2O2, NaOCl, O2, KOCl, and air.
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Page/Page column 9
(2008/12/08)
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- Oxidative rearrangement of tertiary allylic alcohols employing oxoammonium salts
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(Chemical Equation Presented) Practical and highly efficient methods for oxidative rearrangement of tertiary allylic alcohols to β-substituted α,β-unsaturated carbonyl compounds employing oxoammonium salts are described. The methods developed are applicable to acyclic substrates as well as medium membered ring substrates and macrocyclic substrates. The counteranion of the oxoammonium salt plays crucial roles on this oxidative rearrangement.
- Shibuya, Masatoshi,Tomizawa, Masaki,Iwabuchi, Yoshiharu
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p. 4750 - 4752
(2008/09/20)
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- Syntheses and reactions of allyl phenylselenides. A convenient method of the allyl methylcarbamates synthesis
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Allyl phenylselenides from terpene systems are convenient precursors for the synthesis of the terpene allyl alcohols and allyl methylcarbamates. Using optically active allyl phenylselenides corresponding optically active oxygen and nitrogen derivatives were obtained. A new one-step method of the allyl methylcarbamates synthesis from allyl phenylselenides was described.
- Scianowski,Tafelska-Kaczmarek
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p. 529 - 534
(2008/09/19)
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- Cyclization by intramolecular carbolithiation of alkyl- and vinyllithiums prepared by the action of aromatic radical anions on phenyl thioethers. High stereoselectivity in the cyclization accelerated by an allylic lithium oxyanion
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The reductive lithiation of alkyl and vinyl phenyl thioethers by aromatic radical anions is shown to be the most general method yet known for preparing organolithiums capable of intramolecular carbometalation of unactivated alkenes to produce five-membered rings and in one case a four-membered ring (in a far higher yield than known cases). The relative rates of cyclization for alkyllithiums are secondary > tertiary > primary, and the yields are very high. In the secondary case, the stereoselectivity is extremely high, producing a cyclopentylmethyllithium with a trans-2-alkyl substituent. A remarkable finding is that for all of the organolithiums a lithium oxyanionic group in the proximal allylic position to the alkene greatly accelerates the cyclization and leads almost exclusively to a trans relationship between the CH2Li group and the OLi group, the opposite relationship from that observed in intramolecular carbolithiations by allyllithiums. A mechanistic rationale for this divergence is discussed. One of the two types of proximal homoallylic lithium oxyanions exerts an analogous effect. An intriguing limitation, even occurring with the highly reactive secondary organolithium and in the presence of an allylic oxyanionic group, is the failure of intramolecular carbolithiation when a methyl group is at the terminus of the alkene.
- Deng, Kai,Bensari-Bouguerra, Ahlem,Whetstone, Joseph,Cohen, Theodore
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p. 2360 - 2372
(2007/10/03)
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- Oxidative rearrangement of cyclic tertiary allylic alcohols with IBX in DMSO
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(Chemical Equation Presented) A practical and environmentally friendly method for oxidative rearrangement of five- and six-membered cyclic tertiary allylic alcohols to β-disubstituted α,β-unsaturated ketones by the IBX/DMSO reagent system is described. Several conventional protecting groups (e.g., Ac, MOM, and TBDPS) are compatible under the reaction conditions prescribed.
- Shibuya, Masatoshi,Ito, Shinichiro,Takahashi, Michiyasu,Iwabuchi, Yoshiharu
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p. 4303 - 4306
(2007/10/03)
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- Palladium Nanoparticles by Electrospinning from Poly(acrylonitrile-co-acrylic acid)-PdCl2 Solutions. Relations between Preparation Conditions, Particle Size, and Catalytic Activity
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Catalytic palladium (Pd) nanoparticles on electrospun copolymers of acrylonitrile and acrylic acid (PAN-AA) mats were produced via reduction of PdCl2 with hydrazine. Fiber mats were electrospun from homogeneous solutions of PAN-AA and PdCl2 in dimethylformamide (DMF). Pd cations were reduced to Pd metals when fiber mats were treated in an aqueous hydrazine solution at room temperature. Pd atoms nucleate and form small crystallites whose sizes were estimated from the peak broadening of X-ray diffraction peaks. Two to four crystallites adhere together and form agglomerates. Agglomerate sizes and fiber diameters were determined by scanning and transmission electron microscopy. Spherical Pd nanoparticles were dispersed homogeneously on the electrospun nanofibers, The effects of copolymer composition and amount of PdCl2 on particle size were investigated. Pd particle size mainly depends on the amount of acrylic acid functional groups and PdCl2 concentration in the spinning solution. Increasing acrylic acid concentration on polymer chains leads to larger Pd nanoparticles. In addition, Pd particle size becomes larger with increasing PdCl2 concentration in the spinning solution. Hence, it is possible to tune the number density and the size of metal nanoparticles. The catalytic activity of the Pd nanoparticles in electrospun mats was determined by selective hydrogenation of dehydrolinalool (3,7-dimethyloct-6-ene-l-yne-3-ol, DHL) in toluene at 90°C. Electrospun fibers with Pd particles have 4.5 times higher catalytic activity than the current PoVAl2O3 catalyst.
- Demir, Mustafa M.,Gulgun, Mehmet A.,Menceloglu, Yusuf Z.,Erman, Burak,Abramchuk, Sergei S.,Makhaeva, Elena E.,Khokhlov, Alexei R.,Matveeva, Valentina G.,Sulman, Mikhail G.
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p. 1787 - 1792
(2007/10/03)
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- Bismuth triflate: An efficient catalyst for the formation and deprotection of tetrahydropyranyl ethers
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The tetrahydropyranylation of alcohols under solvent-free conditions is efficiently catalyzed by bismuth triflate (0.1 mol %). The experimental procedure is simple and works well with a variety of alcohols and phenols. The catalyst is insensitive to air and small amounts of moisture, easy to handle and relatively nontoxic. The deprotection of THP ethers is also catalyzed by bismuth triflate (1.0 mol %). ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
- Stephens, Jacqueline R.,Butler, Phillip L.,Clow, Curtis H.,Oswald, Matthew C.,Smith, Russell C.,Mohan, Ram S.
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p. 3827 - 3831
(2007/10/03)
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- A Convenient Method for Protection and Deprotection of Alcohols and Phenols as Alkylsilyl Ethers Catalyzed by Iodine under Microwave Irradiation
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Irradiation of alcohols or phenols with tert-butyldimethylsilyl chloride (TBDMSCl) or trimethylsilyl chloride (TMSCl) in presence of catalytic amount (20 mol%) of iodine in a microwave oven for 2 min gives the corresponding silyl ethers in excellent yield. Iodine in methanol deprotects the silyl ether into its parent alcohol or phenol under similar reaction conditions.
- Saxena, Ira,Deka, Nabajyoti,Sarma, Jadab C.,Tsuboi, Sadao
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p. 4185 - 4191
(2007/10/03)
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- Hydrogenation on granular palladium-containing catalysts: I. Hydrogenation of tertiary acetylene alcohols
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Commercial granular palladium catalyst (0.5% of Pd on γ-Al 2O3) was modified by treating with zinc acetate (type 1) or successively with zinc acetate and ammonia (type 2). The treatment significantly increased the hydrogenation selectivity for a triple bond into a double bond: to 85.3-93.1% with the type 1 catalyst and to 96.3-97.8% with the type 2 catalyst. A construction of an autoclave with a fixed bed of the granular catalyst is described.
- Tolkacheva,Kislyi,Taits,Semenov
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p. 150 - 152
(2007/10/03)
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- A New, Simple, and Selective Palladium-Catalyzed Cleavage of Triethylsilyl Ethers
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(Equation Presented) A simple procedure for the cleavage of triethylsilyl (TES) ethers in the presence of 10 wt % Pd/C in methanol or 95% ethanol is reported. This method allows selective removal of alkyl TES ethers in the presence of aromatic TES ethers or tert-butyldimethylsilyl (TBS) protecting groups.
- Rotulo-Sims, Delphine,Prunet, Joelle
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p. 4701 - 4704
(2007/10/03)
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- Compounds having protected hydroxy groups
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The present invention relates to compounds with protected hydroxy groups of formula (I) These compounds are precursors for organoleptic agents, such as fragrances, and masking agents and for antimicrobial agents. When activated, the compounds of formula (I) are cleaved and form one or more organoleptic and/or antimicrobial compounds.
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- Synthesis and reactions of organic compounds with a nitrogen atom. Part XVII. Reactions of acyclic and monocyclic chlorides with phenyltelluro- and phenylselenosodium
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The reaction of neryl (3), geranyl (4), (+)-carvotanacetyl (5), (-)-carvyl (6) and perillyl (7) chlorides with phenylseleno-(1) or phenyltellurosodium (2), and then with chloramine-T afforded α,β-unsaturated toluenesulfonamides 8-11, which were reduced with sodium in liquid ammonia to allylic amines 12-15. Allylic phenyltellurides were oxidized by air to carbonyl compounds 29-31 or alcohol 28.
- Bakowska-Janiszewska,Scianowski,Uzarewicz
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p. 649 - 656
(2007/10/03)
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- Purification and characterization of an α-L-rhamnosidase from Pichia angusta X349
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An intracellular α-L-rhamnosidase from Pichia angusta X349 was purified to homogeneity through four chromatographic steps. The α-L-rhamnosidase appeared to be a monomeric protein with a molecular mass of 90 kDa. The enzyme had an isoelectric point at 4.9, and was optimally active at pH 6.0 and at around 40°C. The Ki for L-rhamnose inhibition was 25 mM. The enzyme was inhibited by Cu2+, Hg2+, and p-chloromercuribenzoate. The α-L-rhamnosidase was highly specific for α-L-rhamnopyranoside and liberated rhamnose from naringin, rutin, hesperidin, and 3-quercitrin. The α-L-rhamnosidase was active at the ethanol concentrations of wine. It efficiently released monoterpenols, such as linalool and geraniol, from an aroma precursor extracted from Muscat grape juice.
- Yanai, Takaaki,Sato, Michikatsu
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p. 2179 - 2185
(2007/10/03)
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- Acid-catalyzed hydrolysis of alcohols and their β-D-glucopyranosides
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The hydrolysis, in model wine at pH 3, of the allylic, homoallylic, and propargylic glycosides, geranylβ-D-glucopyranoside, [3'-(1'-cyclohexenyl)- 1'-methyl-2'-propynyl]-β-D-glucopyranoside, (3'RS,9'SR)(3'-hydroxy-5'- megastigmen-7-yn-9-yl)-β-D-glucopyranoside, (3',5',5'-trimethyl-3'- cyclohexenyl)-β-D-glucopyranoside, E-(7'-oxo-5',8'-megastigmadien-3'-yl)-β- D-glucopyranoside (3-hydroxy-β-damascone-β-D-glucopyranoside), and their corresponding aglycons has been studied. In general, aglycons were more rapidly converted to transformation products than were the corresponding glucosides. Glycoconjugation of geraniol in grapes is a process that reduces the flavor impact of this compound in wine, not only because geraniol is an important flavor component of some wines but also because the rate of formation of other flavor compounds from geraniol during bottle-aging is reduced. However, when flavor compounds such as β-damascenone are formed in competition with flavorless byproducts, such as 3-hydroxy-β-damascone, by acid-catalyzed hydrolytic reactions of polyols, then glycoconjugation is a process that could enhance as well as suppress the formation of flavor, depending on the position of glycosylation. (3'RS,9'SR)-(3'-Hydroxy-5'- megastigmen-7'-yn-9'-yl)-β-D-glucopyranoside hydrolyzed more slowly but gave a higher proportion of β-damascenone in the products than did the aglycon at 50 °C. Reaction temperature also effected the relative proportion of the hydrolysis products. Accelerated studies do not parallel natural processes precisely but only approximate them.
- Skouroumounis, George K.,Sefton, Mark A.
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p. 2033 - 2039
(2007/10/03)
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- P(MeNCH2CH2)3N: An efficient catalyst for the desilylation of tert- butyldimethylsilyl ethers
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tert-Butyldimethylsilyl (TBDMS) ethers of primary, secondary, and tertiary alcohols and phenolic TBDMS ethers are desilylated to their corresponding alcohols and phenols, respectively, in DMSO, at 80 °C, in 68- 94% yield in the presence of 0.2-0.4 equiv of P(MeNCH2CH2)3N. Using P(i- PrNCH2CH2)3N as the catalyst, 85-97% yields of desilylated alcohols were obtained from TBDMS ethers of 1-octanol, 2-phenoxyethanol, and racemic α- phenyl ethanol. These are the first examples of desilylations of silyl ethers catalyzed by nonionic bases. Both catalysts were much less effective for the desilylation of tert-butyldiphenylsilyl (TBDPS) ethers (22-45% yield) under the same conditions as used for TBDMS ethers. Possible pathways involving nucleophilic attack of the anion of the solvent molecule (generated by the catalyst) at the Si-O bond of silyl ether or a prior activation of the silyl ether by the catalyst via a P-Si interaction followed by nucleophilic attack of the solvent anion are proposed on the basis of 1H and 31P NMR experimental data.
- Yu, Zhengkun,Verkade, John G.
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p. 2065 - 2068
(2007/10/03)
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- A facile route to acyclic substituted α,β-unsaturated aldehydes: The allene claisen rearrangement
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(equation presented) Sigmatropic rearrangement of allenyl ethers furnishes α,β-unsaturated aldehydes in good yield.
- Parsons, Philip J.,Thomson, Peter,Taylor, Andrew,Sparks, Timothy
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p. 571 - 572
(2007/10/03)
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- Convenient cleavage of water-insoluble allylic substrates in the presence of per(2,6-di-O-methyl)-β-cyclodextrin
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The removal of allylic protecting groups promoted by a water soluble palladium complex of the trisulfonated triphenylphosphine is achieved in very high yields (95-100%) on a wide range of water-insoluble substrates in a genuine two-phase system by using the per(2,6-di-O-methyl)-β-cyclodextrin as inverse phase transfer catalyst. The catalytic activities were up to 1000 times higher than those observed without cyclodextrin.
- Widehem, Rodrigue,Lacroix, Thibaut,Bricout, Herve,Monflier, Eric
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p. 722 - 724
(2007/10/03)
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- Epoxides from myrcene: New versatile tools for the synthesis of functionalized acyclic terpenoids
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Mono-epoxides prepared from myrcene, were used as synthetic intermediates to obtain citral, linalool, geranylacetone and pseudo-ionone.
- Fauchet,Miguel, B. Arreguy-San,Taran,Delmond
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p. 3673 - 3684
(2007/10/03)
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- Enzymatic alcoholysis of alkoxymethyl alkanoates: A possible approach for the kinetic resolution of tertiary alcohols
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The pivaloyloxymethyl and butanoyloxymethyl derivatives of tert-butanol and linalool (1.4) are readily accepted by hydrolases. Linalool derivative 4b is alcoholysed stereoselectively by Candida rugosa lipase (E=9.7).
- Franssen, Maurice C.R.,Goetheer, Earl L.V.,Jongejan, Hugo,De Groot, Aede
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p. 8345 - 8348
(2007/10/03)
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- Facile one-pot transformation of 2,3-epoxy alcohols into allylic alcohols: First total synthesis of (-)-4-O-(6'-hydroxy- 7'(9')-dehydro- 6',7'-dihydrogeranyl)coniferol
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An efficient and practical synthesis of optically active allylic alcohols from 2,3-epoxy alcohols by the in situ formation of the epoxy iodides and their subsequent reduction with phosphine hydroxyiodide has been established. Using this reaction as the key step, we synthesized (-)-4-O- (6'-hydroxy-7'(9')-dehydro-6',7'-dihydrogeranyl)coniferol.
- Liu, Zuosheng,Lan, Jiong,Li, Yulin
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p. 3755 - 3762
(2007/10/03)
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- Selective Hydrogenation of Dehydrolinalool and Dehydroisophytol in a Liquid Film Moving over Pd-Ru Foil
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Selective hydrogenation of dehydrolinalool (DHL) and dehydroisophytol (DHI) on a catalyst made of a palladium-ruthenium (6 wt percent) alloy rolled into a foil 0.05 mm thick was studied.Hydrogenation of the acetylene alcohols was conducted without a solvent in a flow reactor, while a film of the liquid moved over the surface of the catalyst rolled up into a frustum of a cone rotating about its axis.The compounds were hydrogenated at several temperatures by hydrogen, which reached the surface of the catalyst by diffusion through the liquid.Hydrogenation selectivity was improved by adding CO to hydrogen.In the presence of CO, the reaction in the kinetic region was first-order with respect to hydrogen and zeroth-order with respect to the alcohols undergoing hydrogenation.Under identical conditions, DHL was hydrogenated more selectively and at a rate two times higher than DHI.Maximum selectivity (0.995) was attained at 383 K; hydrogen and CO pressures were 0.15 and 0.05 MPa, respectively, for DHL and 0.05 and 0.25 MPa for DHI.In the presence of CO, hydrogenation of DHL and DHI followed qualitatively similar patterns.
- Maganyuk, A. P.,Gizhevskii, S. F.,Gryaznov, V. M.
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p. 1244 - 1247
(2007/10/03)
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- Zeolite Assisted Dehydration of Terpenic Alcohols : Convenient Synthesis of 1,3-Dienes and Oxepane
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Terpenic alcohols undergo facile dehydration over H-ZSM-5 to yield 1,3-dienes, such as farnesenes, ocimene, myrcene and isoprene. Studies on homoallylic alcohol (1e) gave oxepane (2e).
- Reddy, P. Veera,Bhat, Sujata V.
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p. 688 - 689
(2007/10/03)
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- Tellurium in the 'no-solvent' organic synthesis of allylic alcohols
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Elemental tellurium can be reduced by rongalite (HOCH2SO2Na·2H2O)-KOH in the solid phase by application of ultrasound or by microwave irradiation. Without solvent, the organic substrate leg sulfonate ester of an oxiranemethanol) is added with further sonication or irradiation to yield the desired organic product leg allylic alcohols) and elemental Te which may be recycled Phase-transfer conditions (water-toluene) also are satisfactory.
- Xu, Qinyu,Chao, Bin,Wang, Yongmei,Dittmer, Donald C.
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p. 12131 - 12146
(2007/10/03)
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- Dependence of the rates of dehydrolinalool hydrogenation over membrane catalysts from palladium-eighth group metal alloys on their electronic structure
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The calculations of the electron work function, the filling number of the d band, and the density of states at the Fermi level for various binary alloys of Pd with Fe, Ni, Ru, Rh, and Pt allows us to explain the changes in the catalytic activity of the alloys in dehydrolinalool hydrogenation. It is found that the catalytic activity of the alloys increases when the electron work function is reduced compared to that of pure Pd, and the activity decreases when both the density of states at the Fermi level and the filling of the d-band of the alloys decrease. A semiempirical equation is proposed that accounts for the above parameters of the electronic structure and permits fitting the calculated values of the reaction rates to the experimental ones with a correlation coefficient of 0.87.
- Karavanov,Batyrev,Roshan,Leiro
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p. 674 - 676
(2007/10/03)
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- Allylic amine formation by imination of allylic tellurides
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The imination of allylic phenyl tellurides with [N-(p-toluenesulfonyl)imino]phenyliodinane or chloramine-T affords the corresponding allylic amines via [2,3]sigmatropic rearrangement of the tellurimide intermediates in high yields. Application to chiral cinnamyl 2-(1-dimethylaminoethyl)ferrocenyl telluride results in the formation of the corresponding chiral allylic amine, 3-phenyl-3-tosylaminopropene, with 93% ee.
- Nishibayashi, Yoshiaki
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p. 6725 - 6728
(2007/10/02)
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- Concomitant Epoxide Deoxygenation and Deacetylation of Glycidyl Acetates Induced by Telluride Ion
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Treatment of glycidyl acetates with telluride ion (Te(2-)) produced by reduction of elemental Te with LiEt3BH yields allylic alcohols by loss of the epoxide oxygen atom and the acetyl group from the ester.If the glycidyl acetate is disubstituted at C-3, a rearrangement to an isomeric allylic alcohol competes with the deoxygenation-deacetylation.Triethylborane, a byproduct in the reduction of Te, is believed to play an important role as a Lewis acid since when it is absent or removed by addition of fluoride ion the reaction is extremely slow.
- Dittmer, Donald C.,Zhang, Yanzhi,Discordia, Robert P.
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p. 1004 - 1010
(2007/10/02)
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