- Asymmetric whole-cell bioreduction of an α,β-unsaturated aldehyde (citral): competing prim-alcohol dehydrogenase and C-C lyase activities
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Asymmetric bioreduction of (E/Z)-3,7-dimethyl-2,6-octadienal (citral) using the enoate reductase activity of whole cells of yeasts, bacteria and fungi, gave the α,β-saturated aldehyde (R)-3,7-dimethyl-6-octenal (citronellal), which constitutes an important flavour component, in up to ≥95% ee. Depending on the microorganism, various amounts of prim-alcohols (nerol/geraniol and citronellol) were formed due to the action of competing prim-alcohol dehydrogenases. Citral lyase activity-leading to the loss of a C2-fragment (acetaldehyde) forming sulcatone-and oxidation of the aldehyde moiety yielding the carboxylic acid (geranic/neric acid) were detected as additional metabolic activities.
- Hall, Melanie,Hauer, Bernhard,Stuermer, Rainer,Kroutil, Wolfgang,Faber, Kurt
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- Generation of norisoprenoid flavors from carotenoids by fungal peroxidases
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To biotechnologlcally produce norisoprenoid flavor compounds, two extracellular peroxidases (MsP1 and MsP2) capable of degrading carotenoids were isolated from the culture supematants of the basidiomycete Marasmlus scorodonlus (garlic mushroom). The encod
- Zelena, Kateryna,Hardebusch, Bjoern,Huelsdau, Baerbel,Berger, Ralf G.,Zorn, Holger
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- -SIGMATROPIC REARRANGEMENTS OF THE ACETOACETATES OF ALLYL ALCOHOLS (CARROLL REACTION) AND ALLYLPHENYL ETHERS (CLAISEN REACTION) ON THE SURFACE OF ADSORBENTS
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A method has been developed for effecting rearrangements of allylacetoacetates to γ,δ-unsaturated ketones (Carroll rearrangement) and allylaryl ethers to the corresponding allylphenols (Claisen rearrangement) under conditions of adsorption on aluminum oxide and silica gel.The method provides a sharp reduction of the temperature of these reactions and improvement of their efficiency.
- Pogrebnoi, S. I.,Kal'yan, Yu. B.,Krimer, M. Z.,Smit, V. A.
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- CARROL REARRANGEMENT ON THE SURFACE OF CHROMATOGRAPHIC GRADE ALUMINA
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Thermolysis on the surface of AL2O3 is proposed as a mild and convenient preparative method for -sigmatropic Carrol rearrangement of acetoacetic esters of tertiary allyl alcohols into respective γ,δ-unsaturated ketones.
- Pogrebnoi, S. I.,Kalyan, Y. B.,Krimer, M. Z.,Smit, W. A.
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- Biotransformation of geraniol and nerol by spores of Penicillium italicum
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A simple and efficient method was developed to carry out biotransformation reactions on volatile terpenoid compounds. Both geraniol and nerol were transformed into 6-methyl-5-hepten-2-one by sporulated surface cultures of Penicillium italicum over prolonged periods (up to 2 months). The bioconversion was followed by dynamic headspace techniques. Copyright
- Demyttenaere, Jan C.R.,De Footer, Herman L.
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- A simple and practical phase-separation approach to the recycling of a homogeneous metathesis catalyst
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The air stable asarone-derived Ru carbene 16, a robust olefin metathesis catalyst, can be easily separated after reaction by deposition on silica gel and reused up to nine times. This procedure provides products of excellent purity with low Ru content. The Royal Society of Chemistry 2006.
- Michrowska, Anna,Gulajski, Lukasz,Grela, Karol
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- Orchestration of concurrent oxidation and reduction cycles for stereoinversion and deracemisation of sec-alcohols
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Black and white are opposites as are oxidation and reduction. Performing an oxidation, for example, of a sec-alcohol and a reduction of the corresponding ketone in the same vessel without separation of the reagents seems to be an impossible task. Here we show that oxidative cofactor recycling of NADP + and reductive regeneration of NADH can be performed simultaneously in the same compartment without significant interference. Regeneration cycles can be run in opposing directions beside each other enabling one-pot transformation of racemic alcohols to one enantiomer via concurrent enantioselective oxidation and asymmetric reduction employing defined alcohol dehydrogenases with opposite stereo- and cofactor-preference. Thus, by careful selection of appropriate enzymes, NADH recycling can be performed in the presence of NADP+ recycling to achieve overall, for example, deracemisation of sec-alcohols or stereoinversion representing a possible concept for a "green" equivalent to the chemical-intensive Mitsunobu inversion.
- Voss, Constance V.,Gruber, Christian C.,Faber, Kurt,Knaus, Tanja,Macheroux, Peter,Kroutil, Wolfgang
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- Novel polymer effect in cleavage reactions of acetals and silyl ethers in aqueous media catalyzed by a polymer-supported dicyanoketene acetal
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Deprotecting reactions of acetals including acetonides, ethylene acetals, and THP ethers of alcohols, an aldehyde, and ketones, and silyl ethers of primary and secondary alcohols were investigated using dicyanoketene acetals (DCKA) and a polymersupported DCKA as a π-acid promoter in aqueous acetonitrile and a single aqueous medium. In all reactions catalytic activity of the polymer-supported DCKA was found to be much higher than that of the molecular DCKAs and an excellent polymer effect was observed. Particularly in the deacetalization reactions in water, difference of catalytic efficiency between the polymer-supported DCKA and the molecular DCKAs was remarkable.
- Masaki,Yamada,Tanaka
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- Synthesis of sesquiterpene polyene hydroperoxides by regio- and stereoselective transposition reactions
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Isomeric unsaturated alcohols (8), (16), (18) and (20), on exposure to hydrogen peroxide or water in the presence of an acid catalyst, undergo exceptionally regio- and stereoselective substitution reactions to form hydroperoxide (3) and alcohol (8) respectively. E/Z isomeric ratios of transposition products indicate that the intermediate acyclic carbocations (21) and (22) are not interconverting under the reaction conditions. Practical syntheses of α-farnesene autoxidation products have been developed based on these transposition reactions.
- Fielder, Simon,Rowan, Daryl D.,Sherburn, Michael S.
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- Two-carbons homologation of methyl ketones examplified for the synthesis of citral from 6-methyl-5-hepten-2-one
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New facile syntheses of 3,7-dimethyl-octadien-2,6-al (citral) from homologation of 6-methyl-5-hepten-2-one are reported.
- Valla, Alain,Cartier, Dominique,Laurent, Alain,Valla, Benoist,Labia, Roger,Potier, Pierre
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- A QUINONE-HYDROQUINONE COUPLE FROM THE BROWN ALGA CYSTOSEIRA STRICTA
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(2'E,6'E)-2-(10',11'-Dihydroxygeranylgeranyl)-6-methylquinol and (2'E,6'E)-2-(10',11'-dihydroxygeranylgeranyl)-6-methyl-1,4-benzoquinone have been isolated from the brown alga Cystoseira stricta.The structures of the new algal metabolites have been elucidated by spectral analysis and chemical degradation. - Key Word Index - Cystoseira stricta; Cystoseiraceae; brown algae; (2'E,6'E)-2-(10',11'-dihydrogeranylgeranyl)-6-methylquinol; (2'E,6'E)-2-(10',11'-dihydroxygeranylgeranyl)-6-methyl-1,4-benzoquinone.
- Amico, Vincenzo,Oriente, Giovanna,Piattelli, Mario,Ruberto, Giuseppe,Tringali, Corrado
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- Biocatalysis with the milk protein β-lactoglobulin: Promoting retroaldol cleavage of α,β-unsaturated aldehydes
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Enzymes with a hydrophobic binding site and an active site lysine have been suggested to be promiscuous in their catalytic activity. β-Lactoglobulin (BLG), the principle whey protein found in milk, possesses a central calyx that binds non-polar molecules. Here, we report that BLG can catalyze the retro-aldol cleavage of α,β-unsaturated aldehydes making it a naturally occurring protein capable of catalyzing retro-aldol reactions on hydrophobic substrates. Retroaldolase activity was seen to be most effective on substrates with phenyl or naphthyl side-chains. Use of a brominated substrate analogue inhibitor increases the product yield by a factor of three. BLG's catalytic activity and its ready availability make it a prime candidate for the development of commercial biocatalysts.
- Gowda, Vishruth,Foley, Brendan,Du, Jasmine,Esteb, Megan,Watanabe, Coran M. H.
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- Pd-Catalyzed Nazarov-Type Cyclization: Application in the Total Synthesis of β-Diasarone and Other Complex Cyclopentanoids
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We describe the palladium-catalyzed Nazarov-type cyclization of easily accessible (hetero)arylallyl acetates to pentannulated (hetero)arenes. This method provides ready access to various types of bi-, tri-, tetra-, and pentacyclic cyclopentanoids under ne
- Singh, Bara,Bankar, Siddheshwar K.,Ramasastry
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supporting information
p. 1043 - 1048
(2022/02/05)
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- Method for synthesizing methyl heptenone from methyl butynol
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The invention provides a method for synthesizing methyl heptenone from methyl butynolwhich. The method comprises the following steps: carrying out a rearrangement reaction on methyl butynol and 2-alkoxy propylene under the action of an acid catalyst to obtain a mixture of allenyl ketone and methylheptadienone; and carrying out selective hydrogenation on the mixture under the action of a hydrogenation catalyst to obtain the methyl heptenone product. The synthesis route is novel, firstly, the rearrangement reaction is firstly carried out to obtain allenyl ketone and methylheptadienone intermediates, and the problem of low selectivity of enol synthesis by alkynol hydrogenation is avoided; sulfonic acid resin and a Lewis acid are used for a synergistic catalytic reaction, so that the rearrangement reaction condition is mild; then hydrogenation of allenyl ketone and methylheptadienone is catalyzed by using a Lindelar catalyst and taking an alkali and quinoline as assistants so as to obtainthe methyl heptenone with high selectivity; and the method has the advantages of readily available starting raw materials, low price, high total yield of the route, good cost advantage and potential application prospect.
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Paragraph 5-11
(2020/05/02)
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- Method for preparing methyl heptenone
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The invention discloses a method for preparing methyl heptanone. According to the method, 3-methyl-2-butene-1-ol and acetone undergoes a selective dehydrogenation coupling reaction under the action ofa rhodium catalyst, alkali and an optional assistant to generate methyl heptenone. Compared with the prior art, the method has the advantages that cheap and easily available 3-methyl-2-butene-1-ol and acetone are used as raw materials; the methyl heptenone with high additional value is prepared through a one-step reaction; and the method is high in atom utilization rate, low in generation of three wastes, mild in conditions and high in selectivity and yield.
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Paragraph 0052-0071
(2020/03/09)
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- Method of preparing gamma-ketene from alpha, gamma-unsaturated diketene
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The invention provides a method of preparing gamma-ketene from alpha, gamma-unsaturated diketene. According to the method, single hydrogen silane is used as a silicon hydrogen reducing agent, a palladium complex is used as a catalyst, a Lewis acid is used as an auxiliary agent, and alpha, gamma-unsaturated diketene are subjected to silicon hydrogen reduction reactions to obtain gamma-ketene through a one-step method. The method has the advantages of mild conditions, simple operation, high product selectivity and yield, cheap and easily available silicon hydrogen reducing agent, high catalystactivity, little using amount, and low cost, and has potential of industrial scale-up.
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Paragraph 0059-0061
(2020/04/06)
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- A ruthenium complex compound for the selective hydrogenation of the dienone method
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The invention provides a selective hydrogenation of ruthenium complex α, γ - unsaturated dienone method, and in particular relates to a method for using the hydrogen in the catalyst under the action of the α, γ - unsaturated dienone is reduced to the corresponding γ - unsaturated ketone of the method, the catalyst employed for ruthenium complex, a ruthenium precursor and the ligand in-situ prepared. Major advantage of this invention is characterized in that the catalyst is composed of metal precursor and the ligand in-situ prepared, simple operation, high catalyst activity; pyridine, quinoline nitrogen-containing aromatic heterocycle such as the adding of the poisoned medicinal preparation, effectively restraining the product γ - unsaturated ketone transition hydrogenation reaction, an excellent selectivity, the cost is low.
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Paragraph 0053-0055
(2019/07/04)
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- Method for selectively hydrogenating alpha, beta-unsaturated carbonyl compound by cobalt complex
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The invention provides a method for selectively hydrogenating an alpha, beta-unsaturated carbonyl compound. The method for selectively hydrogenating the alpha, beta-unsaturated carbonyl compound comprises the steps that first, a cobalt metal precursor and a carbene ligand are coordinated in a solution to obtain a cobalt complex, and the cobalt complex selectively enables the alpha, beta-unsaturated carbonyl compound to be reduced into a corresponding saturated carbonyl compound in a hydrogen atmosphere under the activation of an activator. The method for selectively hydrogenating the alpha, beta-unsaturated carbonyl compound has the main advantages that cobalt is used as a catalyst, and metal cobalt is cheap and easy to obtain relative to noble metal such as palladium, ruthenium, osmium, iridium and platinum, and the catalyst cost is greatly reduced; secondly, the carbene ligand used in the method has the advantages of simple structure, low price, strong coordination ability with cobalt atoms compared with a commonly used phosphine ligand; and finally, the addition of the activator can further significantly increase the activity of the cobalt catalyst. The hydrogenation reaction condition is mild, the reaction rate is high, substantially no carbonyl hydrogenation side reaction occurs, and the carbonyl compound can be obtained in a high yield.
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Paragraph 0061-0063
(2019/11/20)
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- Method for synthesizing methyl heptenone from isopentenyl alcohol
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The invention provides a method for synthesizing methyl heptenone from isopentenyl alcohol. The method comprises the following steps: (1) reacting isopentenyl alcohol with concentrated hydrochloric acid in the presence of a catalyst A, splitting phase for the reacting liquid, washing and distilling the organic phase to obtain a chloro mixture of 1-chloro-3-methyl-2-butene and 3-chloro-3-methyl-1-butene; (2) directly condensing the chloro mixture with acetone in the presence of a catalyst B to obtain a single product methyl heptenone. According to the method, isopentenyl alcohol is efficientlychlorinated in the presence of metal inorganic salt functioning as a catalyst and concentrated hydrochloric acid functioning as a chlorinating agent; the chlorinating reaction liquid is split and simply distilled to obtain the chlorinated mixture, operation steps of isomerization, rectification and the like are not required; alkali solution is promoted by using N,N-dimethyl formamide as a condensation solvent, and a phase transfer catalyst is not required to be added, the condensation time is reduced, and the reaction yield is improved.
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Paragraph 0048; 0051; 0056; 0060; 0064; 0068; 0071
(2019/02/04)
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- NOVEL PROCESS FOR THE MANUFACTURE OF GAMMA,DELTA-UNSATURATED KETONES
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The present invention is directed towards an industrial sustainable process for the manufacture of gamma, delta-unsaturated ketones of formula (III ) in the presence of novel catalysts of formula (IV), wherein R1 is methyl or ethyl, R3 is methyl, R2 is a saturated or unsaturated linear, branched or cyclic hydrocarbyl group with 1 to 46 C atoms, and R and R' are independently from each other selected from the group consisting of linear C1-6-alkyl, branched C3-6-alkyl, aryl and aralkyl (see also Fig.1). The present invention is especially directed towards an industrial sustainable process for the manufacture of 6-methyl-5-hepten-2-one ("MH"; see Fig. 2), 6-methyl-5-octen-2-one ("EH"; see Fig. 3), (5EZ)-6, 10-dimethyl- 5,9-undecadien-2-one (f)-geranylacetone = "GA"; (Z)-nerylacetone = "NA"; see Fig. 4), (5fZ)-6, 10-dimethyl-5-undecen-2-one ((f)-dihydrogeranyl- acetone = "DHGA"; (Z)-dihydronerylacetone = "DHNA"; see Fig. 5) and 6, 10, 14-trimethyl-5,9, 13-pentadeca-trien-2-one (= farnesylacetone; "FA"; see Fig. 6). Preferred catalysts according to the present invention are "DPPI" (diphenyl phosphite), "DMPI" (dimethyl phosphite) and "DBPI" (dibenzyl phosphite).
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(2018/06/06)
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- NOVEL USE OF PHENYL PHOSPHINIC ACID
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The present invention is directed towards a process for the manufacture of gamma, delta-unsaturated ketones of the general formula (III) by reacting a tertiary vinyl carbinol of the general formula (I) with an isopropenyl alkyl ether of the general formula (II) in the presence of a catalyst of the general formula (IV), wherein R1 and R6 are independently from each other methyl or ethyl, R3 is methyl, and R2 is a saturated or unsaturated linear, branched or cyclic hydrocarbyl group with 1 to 46 C atoms. The present invention is also directed towards the reaction mixture as such, i.e. the mixture of the compound of formula (I), the compound of formula (II) and the catalyst of formula (IV).
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- Method for synthesizing methyl heptenone from 2-methyl-3-buten-2-ol
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The invention relates to a method for synthesizing methyl heptenone from 2-methyl-3-buten-2-ol. 2-methyl-3-butene-2-alcohol takes Saucy-Marbet reaction with 2-alkoxylpropylene in the near critical state to obtain methyl heptenone. The synthesis method has the advantages that the use of catalysts is not needed; the selectivity of the product of methyl heptenone can be improved.
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Paragraph 0046-0048; 0066
(2020/09/20)
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- Trityl Cation Catalyzed Intramolecular Carbonyl-Ene Cyclization and [2+2] Cycloaddition
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An unprecedented metal-free catalytic system composed of trityl halides and thioureas has been found to be a convenient source for the generation of trityl cation species, and this cooperative catalytic system was proved to be highly effective for intramolecular carbonyl-ene cyclization and [2+2] cycloadditions.
- Nomoto, Yuya,Horinouchi, Ryo,Nishiyama, Nobuo,Nakano, Keiji,Ichikawa, Yoshiyasu,Kotsuki, Hiyoshizo
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supporting information
p. 265 - 269
(2017/01/25)
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- Γ, δ-higher unsaturated ketone and method for purifying process for preparing
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The invention discloses a preparation process of an advanced gamma and delta-unsaturated ketone. The preparation process of the advanced gamma and delta-unsaturated ketone comprises the following steps: adding an unsaturated alcohol and organic aluminum which serves as a catalyst, adding alkyl acetylacetate, carrying out reaction, and distilling by reducing pressure, wherein the unsaturated alcohol and the organic aluminum are added under the pressure of -0.06Mpa to 0.0Mpa, and the organic aluminum is used as the catalyst. The reaction selectivity is more than 99.5%, the conversion rate is more than 98%, and the yield of the product is more than 95% correspondingly. The prepared product is purified by adopting a purification process, thus the purity of the final product is more than 99.5%, the recovery rate of the final product is more than 99%, and the generation rate of wastes is less than 0.5%.
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Paragraph 0076; 0077; 0078; 0079; 0080; 0081; 0082-0086
(2016/11/28)
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- Microwave-assisted, tetrabutylammonium hydroxide catalysed 1,4-addition of water to α,β-unsaturated ketones and α,β-ynones in aqueous solution
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Microwave-assisted, tetrabutylammonium hydroxide catalysed 1,4-addition reactions of water to α,β-unsaturated ketones and α,β-ynones take place efficiently in water. Reactions of the resulting β-hydroxy ketones lead to the formation of either C-C bond cleavage or annulation products. This journal is
- Lee, Hyejeong,Jun, Chul-Ho
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p. 48331 - 48335
(2014/12/11)
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- A reusable unsupported rhenium nanocrystalline catalyst for acceptorless dehydrogenation of alcohols through γ-C-H activation
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Rhenium nanocrystalline particles (Re NPs), of 2 nm size, were prepared from NH4ReO4 under mild conditions in neat alcohol. The unsupported Re NPs convert secondary and benzylic alcohols to ketones and aldehydes, respectively, through catalytic acceptorless dehydrogenation (AD). The oxidant- and acceptor-free neat dehydrogenation of alcohols to obtain dihydrogen gas is a green and atom-economical process for making carbonyl compounds. Secondary aliphatic alcohols give quantitative conversion and yield. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Re K-edge X-ray absorption near-edge structure (XANES), and X-ray absorption fine structure (EXAFS) data confirmed the characterization of the Re NPs as metallic rhenium with surface oxidation to rhenium(IV) oxide (ReO2). Isotope labeling experiments revealed a novel γ-CH activation mechanism for AD of alcohols. Active particles: A rhenium nanoparticle (Re NP) catalyst is generated from NH4ReO4 under mild solution conditions in neat 3-octanol at 180°C. The resulting Re NPs catalyze acceptorless dehydrogenation of alcohols through a novel C-H activation pathway, and are fully recyclable. Copyright
- Yi, Jing,Miller, Jeffrey T.,Zemlyanov, Dmitry Y.,Zhang, Ruihong,Dietrich, Paul J.,Ribeiro, Fabio H.,Suslov, Sergey,Abu-Omar, Mahdi M.
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supporting information
p. 833 - 836
(2014/01/23)
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- Polydentate pyridyl ligands and the catalytic activity of their iron(II) complexes in oxidation reactions utilizing peroxides as the oxidants
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The paper describes the synthesis of iron(II) complexes bearing new polydentate N,O-coordinating pyridyl ligands and their catalytic application in oxidation reactions employing peroxides as the oxidants. The tridentate N,O,N (10) and N,N,O (11) ligands, the tetradentate N,N,O,N ligand 12 and the pentadentate N,N,N,O,N-coordinating ligand 16 were synthesized, and obtained as oils or solids in 74-93% isolated yields. The ligands were subsequently converted to the iron complexes [Fe(10)2](OTf)2, [Fe(11)2](OTf)2, [Fe(12)(OTf)2] and [Fe(16)(OTf)](OTf), which were obtained as tan powders in 90-94% yield and characterized by various instrumental techniques. Preliminary screening experiments revealed that all complexes are catalytically active in the oxidation of secondary alcohols and benzylic methylene groups to the corresponding ketones. Optimization experiments with the complex [Fe(12)(OTf)2] yielded a system that provided under mild condition ketones from benzylic methylene groups and secondary alcohols in 63-90% isolated yields (3 mol% catalyst loading, 3 equiv. H2O2 in CH 3CN for 2 h at room temperature). Similar conditions utilizing environmentally friendly acetone as the solvent and 4 equiv. tBuOOH resulted in 36-65% isolated yields for some of the substrates, indicating a somewhat lower catalytic activity in that solvent. For the complexes [Fe(10)2](OTf)2 (two tridentate ligands), [Fe(12)(OTf)2] (one tetradentate ligand) and [Fe(16)(OTf)](OTf) (one pentadentate ligand), the product formation for a test reaction was followed over time at significantly reduced catalyst loading to determine activities. Under these conditions, the complex [Fe(10)2](OTf)2 exhibited a somewhat lower catalytic activity compared to the other two complexes. Thus, the denticity seems to have an impact on catalytic activity although it is not dramatic, and a higher denticity appears to be beneficial for catalysis.
- Lenze, Matthew,Sedinkin, Sergey L.,Bauer, Eike B.
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p. 161 - 171
(2013/06/27)
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- Reduction of citral in water under typical transfer hydrogenation conditions-Reaction mechanisms with evolution of and hydrogenation by molecular hydrogen
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The reduction of an α,β-unsaturated aldehyde, citral, was investigated over a 10 wt% Pd catalyst under transfer hydrogenation (TH) conditions in a closed system with microwave assistance. Surprisingly, it was found that hydrogen was produced quite fast under the microwave irradiation during the reaction, and the reduction of citral was proved to go mainly through consecutive pathways of hydrogen production - hydrogenation rather than those commonly considered for TH reactions. Similar reaction pathways were also observed with a homogeneous catalyst of [RuCl2(C6H 6)]2 and other typical hydrogen donors like formate salts and isopropanol, which are usually used in the typical transfer hydrogenations.
- Liu, Ruixia,Wang, Yu,Cheng, Haiyang,Yu, Yancun,Zhao, Fengyu,Arai, Masahiko
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p. 315 - 320
(2013/02/23)
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- Biotransformations of terpenes by fungi from amazonian Citrus plants
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The biotransformations of (RS)-linalool (1), (S)-citronellal (2), and sabinene (3) with fungi isolated from the epicarp of fruits of Citrus genus of the Amazonian forest (i.e., C. limon, C. aurantifolia, C. aurantium, and C. paradisiaca) are reported. The
- Moreno Rueda, Maria Gabriela,Guerrini, Alessandra,Giovannini, Pier Paolo,Medici, Alessandro,Grandini, Alessandro,Sacchetti, Gianni,Pedrini, Paola
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p. 1909 - 1919
(2013/11/06)
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- Secondary amine catalyzed retro-aldol reactions of enals and enones: One-pot conversion of enals to α-substituted derivatives
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A practical synthetic procedure to hydrolytically cleave the C,C-double bond of α,β-unsaturated aldehydes and ketones has been developed. Secondary amines are employed as organocatalysts for the retro-aldol process under simple and mild reaction conditions. Beside the generation of the parent aromatic aldehydes, the synthetic procedure has been successfully used in a one-pot reaction sequence to convert simple cinnamaldehydes into their α-aryl/alkyl substituted derivatives.
- Enders, Dieter,Nguyen, Thanh V.
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scheme or table
p. 2091 - 2095
(2012/07/14)
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- Unexpected cycloisomerizations of nonclassical carbocation intermediates in gold(I)-catalyzed homo-rautenstrauch cyclizations
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An unexpected gold(I)-catalyzed homo-Rautenstrauch rearrangement of 1-cyclopropyl propargylic esters to cyclohexenones is disclosed. This rearrangement represents new evidence for the recently discussed gold-stabilized nonclassical carbocation character of intermediates in gold catalysis. A mechanistic study proved partial chirality transfer from optically active propargyl acetates.
- Wang, Guan,Zou, Yue,Li, Zhiming,Wang, Quanrui,Goeke, Andreas
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p. 5825 - 5831
(2011/09/12)
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- MANUFACTURE OF GAMMA-DELTA-UNSATURATED KETONES
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A process for the manufacture of gamma-delta-unsaturated ketones of formula (R1)(R2)C = CH - CH2 - CH2 - CO - R3 (I), wherein R1 is methyl or ethyl; R2 is a saturated or unsaturated linear or cyclic hydrocarbon residue and R3 is methyl or ethyl, by reacting a tertiary vinyl carbinol of formula (R1)(R2)C(OH) - CH = CH2 (II) with an isopropenyl methyl or ethyl ether of formula H3C-C(OR3) = CH2 (III) in the presence of an ammonium salt as catalyst.
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(2010/05/13)
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- Catalytic decarbonylation of epoxyaldehydes: Applications to the preparation of terminal epoxides
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A catalytic decarbonylation reaction for epoxyaldehydes is reported. This reaction may be sequentially used with known asymmetric methods to access optically active mono- and disubstituted terminal epoxides, as illustrated for a key example. Georg Thieme Verlag Stuttgart.
- Morandi, Bill,Carreira, Erick M.
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experimental part
p. 2076 - 2078
(2011/04/15)
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- An efficient protocol for the oxidative hydrolysis of ketone SAMP hydrazones employing SeO2 and H2O2 under buffered (pH 7) conditions
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An effective oxidative protocol for the liberation of ketones from SAMP hydrazones employing peroxyselenous acid under aqueous buffered conditions (pH 7) has been developed. The procedure proceeds without epimerization of adjacent stereocenters or dehydration, in representative SAMP alkylation and aldol reaction adducts, respectively.
- Smith III, Amos B.,Liu, Zhuqing,Simov, Vladimir
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experimental part
p. 3131 - 3134
(2010/03/24)
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- ALLYL AND PROPARGYL ETHERS
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Allyl and propargyl ethers of the formula X-C(R1)(R2)-O-C(CH3)(R3) - OCH3 (I), wherein X is an ethynyl or vinyl group, R1 is methyl or ethyl, R2 is a saturated or unsaturated linear or cyclic aliphatic hydrocarbon residue and R3 is methyl or ethyl, a method for their preparation and their use in the manufacture of β-keto- allenes, α,β-unsaturated carbonyl compounds and γ,δ-unsaturated ketones.
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Page/Page column 13-14
(2009/12/23)
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- One-way biohydrogen transfer for oxidation of sec-alcohols
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(Chemical Equation Presented) Quasi-irreversible oxidation of sec-alcohols was achieved via biocatalytic hydrogen transfer reactions using alcohol dehydrogenases employing selected ketones as hydrogen acceptors, which can only be reduced but not oxidized. Thus, only 1 equiv of oxidant was required instead of a large excess. For the oxidation of both isomers of methylcarbinols a single nonstereoselective short-chain dehydrogenase/reductase from Sphingobium yanoikuyae was identified and overexpressed in E. coli.
- Lavandera, Ivan,Kern, Alexander,Resch, Verena,Ferreira-Silva, Bianca,Glieder, Anton,Fabian, Walter M. F.,De Wildeman, Stefaan,Kroutil, Wolfgang
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supporting information; experimental part
p. 2155 - 2158
(2009/05/27)
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- A strategy for position-selective epoxidation of polyprenols
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An effective strategy has been developed for the efficient site-selective epoxidation of poylolefinic isoprenoid alcohols, based on the use of an internal control element for intramolecular reaction. The approach is illustrated by application to a series of polyisoprenoid alcohols (polyprenols) at substrate concentration of 0.5 mM. With polyprenol substrates having the hydroxyl function at one terminus, the internal epoxidation can be directed at the double bond of the polyprenol, which is either four or five away from the terminal hydroxyprenyl subunit.
- Gnanadesikan, Vijay,Corey
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supporting information; experimental part
p. 8089 - 8093
(2009/02/01)
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- Emulation of racemase activity by employing a pair of stereocomplementary biocatalysts
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Racemization is the key step to turn a kinetic resolution process into dynamic resolution. A general strategy for racemization under mild reaction conditions by employing stereoselective biocatalysts is presented, in which racemization is achieved by employing a pair of stereocomplementary biocatalysts that reversibly interconvert an sp3 to a sp2 center. The formal interconversion of the enantiomers proceeds via a prochiral sp 2 intermediate the formation of which is catalyzed either by two stereocomplementary enzymes or by a single enzyme with low stereoselectivity. By choosing appropriate reaction conditions, the amount of the prochiral intermediate is kept to a minimum. This general strategy, which is applicable to redox enzymes (e.g., by acting on R2CHOH and R2CHNHR groups) and lyase-catalyzed addition-elimination reactions, was proven for the racemization of secondary alcohols by employing alcohol dehydrogenases. Thus, enantiopure chiral alcohols were used as model substrates and were racemized either with highly stereoselective biocatalysts or by using (rarely found) non-selective enzymes.
- Gruber, Christian C.,Nestl, Bettina M.,Gross, Johannes,Hildebrandt, Petra,Bornscheuer, Uwe T.,Faber, Kurt,Kroutil, Wolfgang
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p. 8271 - 8276
(2008/04/01)
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- Transport of ethyne in form of alpha-alkynols as ethyne precursors
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The present invention relates to a new method for a safe transport of ethyne in form of α-alkynols as precursors for ethyne. The new method comprises three steps. In a first step the synthesis of the α-alkynol(s) is performed by reacting ethyne with (a) carbonyl compound(s). The second step comprises the transport of the resulting α-alkynol(s) in a safe manner, whereas the safety requirements for this transport are not as high as for ethyne because α-alkynol(s) are normally classified for transportation as hazardous class 3. In the third step the α-alkynol(s) can be cleaved and the ethyne and the carbonyl compound(s) can be obtained in the cleavage reaction and can be separated to yield pure products for further applications.
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Page/Page column 6
(2008/06/13)
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- METHOD FOR PRODUCING CARBONYL COMPOUND
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An oily solution of water-insoluble aliphatic alcohol is allowed to react with an aqueous hydrogen peroxide solution in the presence of a catalyst containing a metal compound belonging to Group 8 to 10 of the Periodic Table in a heterogeneous solution system. As a result, a carbonyl compound can be produced from an aqueous hydrogen peroxide solution under mild conditions in high yield. Also, the reaction operation is simple and easy, a step for removing solvent after completion of the reaction is not necessary and influence and toxicity upon the environment and human body are markedly small. Thus, a carbonyl compound can be produced safely, simply and efficiently.
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Page/Page column 5
(2008/06/13)
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- PROCESS FOR THE PREPARATION OF METHYLHEPTENONE
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Methylheptenone (2-methyl-2-hepten-6-one) is prepared by reacting 2-methyl-3-buten-2-ol with isopropenyl methyl ether in the presence of hydrogen tris(oxalato)phosphate or hydrogen bis(oxalato)borate.
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Page/Page column 2-4
(2008/06/13)
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- A new, alternative, halogen-free synthesis for the fragrance compound Melonal using zeolites and mesoporous materials as oxidation catalysts
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At present Melonal (2,6-dimethyl-5-hepten-1-al) fragrance is industrially produced by a Darzens reaction from 6-methyl-5-hepten-2-one, with ethylchloroacetate as reagent. We present here a novel halogen-free synthesis strategy that involves the chemoselective oxidation of Citral (3,7-dimethyl-6-octen-1-al), a common compound in the fragrance industry, with H2O2 and Sn-Beta or Sn-MCM-41 as catalysts. The performance of tin Lewis acid sites is compared with other potential catalytic sites, and it is found that aluminium Bronsted acid sites and zirconium or titanium Lewis acid sites are less efficient and selective than Sn. In the case of Ti, epoxidation by-products could be found. The re-usability of Sn-Beta zeolite is discussed, as is the heterogeneity of the reaction.
- Corma, Avelino,Iborra, Sara,Mifsud, Maria,Renz, Michael
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- The samarium(II)-mediated intermolecular couplings of ketones and β-alkoxyacrylates: A short asymmetric synthesis of an antifungal γ-butyrolactone
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The samarium(II) iodide-mediated coupling of ketones with β-alkoxyacrylates gives β-hydroxy-γ-butyrolactones in moderate yield. The process has been applied to the asymmetric synthesis of an antifungal, γ-butyrolactone natural product.
- Kerrigan, Nessan J.,Upadhyay, Tejas,Procter, David J.
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p. 9087 - 9090
(2007/10/03)
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- Biocatalytic asymmetric hydrogen transfer employing Rhodococcus ruber DSM 44541
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Nonracemic sec-alcohols of opposite absolute configuration were obtained either by asymmetric reduction of the corresponding ketone using 2-propanol as hydrogen donor or by enantioselective oxidation through kinetic resolution of the rac-alcohol using acetone as hydrogen acceptor employing whole lyophilized cells of Rhodococcus ruber DSM 44541. The microbial oxidation/reduction system exhibits not only excellent stereo- and enantioselectivity but also a broad substrate spectrum. Due to the exceptional tolerance of the biocatalyst toward elevated concentrations of organic materials (solvents, substrates and cosubstrates), the process is highly efficient. The simple preparation of the biocatalyst and its ease of handling turns this system into a versatile tool for organic synthesis.
- Stampfer, Wolfgang,Kosjek, Birgit,Faber, Kurt,Kroutil, Wolfgang
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p. 402 - 406
(2007/10/03)
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- Acid-catalyzed reactions of 2,3-epoxy derivatives of citral with alcohols
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Acid-catalyzed reactions of 2,3-epoxy derivatives of citral (which is a widely spread naturally occurring unsaturated aldehyde) with alcohols were studied under conditions of heterogeneous catalysis and in fluorosulfonic acid. A number of new products were obtained, and possible mechanisms of their formation were proposed.
- Yarovaya,Korchagina,Salomatina,Polovinka,Barkhash
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p. 985 - 991
(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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- 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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- Precursors for fragrant ketones and fragrant aldehydes
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The present invention refers to fragrance precursors of formula I for a fragrant ketone of formula II and one or more fragrant aldehydes or ketones of formula III and IV, These fragrance precursors are useful in perfumery, especially in the fine and functional perfumery.
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- (S)-3,7-Dimethyl-2-oxo-6-octene-1,3-diol: An aggregation pheromone of the Colorado potato beetle, Leptinotarsa decemlineata (Say)
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(S)-3,7-Dimethyl-2-oxo-6-octene-1,3-diol has been identified as a male-produced pheromone from the Colorado potato beetle. Its gross structure was deduced from its mass and NMR spectra plus synthesis from geraniol. The absolute configuration was determined to be (S) by syntheses of both enantiomers from (R)- and (S)-linalool, respectively.
- Oliver, James E,Dickens, Joseph C,Glass, Thomas E
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p. 2641 - 2643
(2007/10/03)
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- Continuous preparation of unsaturated ketones
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Process for the continuous preparation of unsaturated ketones of the formula I where the dashed line can be an additional C—C bond, R1is an alkyl, and R2is an aliphatic hydrocarbon having from 1 to 37 carbons, a cycloalkyl or a cycloalkylalkyl, by reacting an unsaturated alcohol of the formula II ?with an alkyl acetoacetate of the formula III where R3is an alkyl having from 1 to 5 carbons, in the presence or organic aluminum compounds as catalyst.
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- Beta-ketoester compounds
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The beta-ketoesters of formula I are useful as precursors for organoleptic compounds, especially for flavors, fragrances and masking agents and antimicrobial compounds.
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- Ketone precursors for organoleptic compounds
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The invention discloses ketones of formula I: wherein, Y is an optionally substituted alkyl, cycloalkyl, or cycloalkylalkyl, wherein each alkyl group is straight or branched and each alkyl and cycloalkyl group is saturated or unsaturated; R1is hydrogen or a C1-6alkyl group that is substituted, saturated or unsaturated, straight or branched; A is a chromophoric substituted aromatic ring or ring system; n is an integer; and with the proviso that formula I is not 2-ethoxy-1-phenyl-ethanone. These compositions are useful for the delivery of organoleptic compounds, especially of flavors, fragrances, masking agents and antimicrobial compounds.
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- Generation of chromioenamines by reduction of O-acetyloximes with chromium(II) and their application
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Chromioenamines can be generated by treatment of O-acetyloximes with chromium(II) via two steps of one-electron reduction and successive isomerization, and the species react with aldehydes to give γ-amino alcohols after reduction with LiA1H4.
- Takai,Katsura,Kunisada
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p. 1724 - 1725
(2007/10/03)
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- Synthesis and characterization of all-E-(4,4'-13C2)-astaxanthin strategies for labelling the C15-end groups of carotenoids
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The all-E isomer of (4,4'-13C2)astaxanthin (1a) has been prepared by total synthesis starting from commercially available 99% 13C enriched acetonitrile. The labelled astaxanthin was obtained in high purity and with high isotope incorporation. For this synthesis, the C15 + C10 + C15 strategy was used. The central C10-synthon, 2,7-dimethylocta-2,4,6-triene- 1,8-dial (3), was coupled with 13C-enriched C15-phosphonium salt 2a. The new synthetic scheme for the preparation of the C15-phosphonium salt is discussed in this paper; the same scheme can be used to label all positions and combinations of positions of the C15-phosphonium salt.
- Jansen, Frans Jos H. M.,Lugtenburg, Johan
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p. 829 - 836
(2007/10/03)
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