- Concurrent Strong Acid and Base Catalysis. Synthesis of Cyclopentenones
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2-Alkyl-2-cyclopenten-1-ones were prepared in one operation from γ-keto aldehyde acetals by acid-catalyzed hydrolysis of the acetal and base-catalyzed aldol cyclization using mixed ion-exchange resins.
- Stowell, John C.,Hauck, Henry F.
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Read Online
- Vinyl esters as ethylene equivalents in the Khand annulation reaction
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A preparatively convenient and mild method for modified Khand cycloadditions is described; vinyl esters are employed as the olefinic reaction partner to provide cyclopentenone products more normally obtained with ethylene.
- Kerr, William J.,McLaughlin, Mark,Pauson, Peter L.,Robertson, Sarah M.
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Read Online
- Catalytic intermolecular Pauson - Khand reactions in supercritical ethylene
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Ethylene is not only a substrate, but also a solvent: Catalytic intermolecular Pauson - Khand reactions of terminal alkynes were carried out in supercritical ethylene to provide 2-substituted cyclopentenones in moderate to high yields. Under these conditions, even a low pressure of CO (5 atm) is sufficient for the reaction to take place.
- Jeong, Nakcheol,Hwang, Sung Hee
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Read Online
- Characterization of initial reaction intermediates in heated model systems of glucose, glutathione, and aliphatic aldehydes
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To understand the effect of lipid degradation on Maillard formation of meaty flavors, initial reaction intermediates in model systems of glucose–glutathione with hexanal, (E)-2-heptenal, or (E,E)-2,4-decadienal were identified by HPLC–MS and by NMR. Besides Amadori compounds, hemiacetals and thiazolidines via addition of sulfhydryl to carbonyl or to the conjugated olefinic bond were found. Concentrations of all intermediates increased with reaction time while degradation of the intermediates with a glutathione moiety helped formation of thiazolidines with cysteinylglycine. The unsaturated aldehydes (E)-2-heptenal and (E,E)-2,4-decadienal exhibited high reactivity against glucose for glutathione, yielding higher levels of intermediate compounds than from glucose. Heating prepared intermediates reversibly released the original aldehydes, which caused various compounds formed by retro-aldol, oxidation, etc. to react with H2S and NH3. Among them, formation pathways including 3-nonen-2-one, 2-hexanoylfuran, and six dialkylthiophenes (e.g., 2-ethyl-5-(1-methylbutyl)thiophene) were proposed for the first time.
- Wang, Tianze,Zhen, Dawei,Tan, Jia,Xie, Jianchun,Cheng, Jie,Zhao, Jian
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- Synthesis of Unsaturated Spiroacetals, Cyclopentanone Derivatives, in the Presence of Natural Aluminosilicate Modified with Zirconium Cations
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Abstract: Conditions for the condensation of cyclopentanone and n-valeric aldehyde to 2-pentylidenecyclopentanone in the presence of an alcoholic solution of piperidine have been developed. The isomerization of the latter in a continuous-flow system over γ-Al2O3 yields 2-pentylcyclopent-2-en-1-one. The condensation of the obtained unsaturated ketones with ethane-1,2-diol in the presence of a heterogeneous catalyst, a natural aluminosilicate (perlite) modified with zirconyl sulfate, has been studied. The optimum conditions for the preparation of the corresponding unsaturated spiroacetals have been found. The synthesized compounds can be used as synthetic fragrances for different purposes.
- Abbasov,Alimardanov, Kh. M.,Abbaszade,Guseinova,Azimli
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p. 603 - 607
(2019/06/24)
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- Aldol Condensation of Cyclopentanone with Valeraldehyde Over Metal Oxides
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Kinetics of the cross aldol condensation of valeraldehyde with cyclopentanone was investigated in a batch reactor under atmospheric pressure at 130?°C using heterogeneous metal modified oxides, such as CeO2–MgO, FeO–MgO, FeO–CaO as well as pristine CaO as catalysts. The catalysts were prepared either by evaporation impregnation or deposition precipitation methods and characterized by XRD, TEM, SEM, nitrogen adsorption, ammonia and CO2 TPD. The results revealed that an optimum amount of strong basic sites gives the highest ratio between cross condensation and self-condensation products of valeraldehyde. The highest yield of the desired product 2-pentylidenecyclopentanone (66%) was obtained with FeO–MgO prepared by the deposition precipitation methods. Graphical Abstract: Cross-condensation of valeraldehyde with cyclopentanone was investigated over heterogeneous Fe–CaO, CeO–MgO, FeO–CaO and CaO catalysts at 130?°C using cyclopentanone as a solvent and reactant. The highest yield of the desired product, 2-pentylidene-cyclopentanone, finding applications as fragrances, flavours and pharmaceuticals, was 66% obtained over FeO–MgO catalyst exhibiting both acid and basic sites.[Figure not available: see fulltext.].
- M?ki-Arvela, P?ivi,Shcherban, Nataliya,Lozachmeur, Chloé,Er?nen, Kari,Aho, Atte,Smeds, Annika,Kumar, Narendra,Peltonen, Janne,Peurla, Markus,Russo, Vincenzo,Volcho, Konstantin P.,Murzin, Dmitry Yu.
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p. 1383 - 1395
(2019/02/26)
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- Method for preparing amyl cyclopentenone through organic solvent-free isomerization in methyl dihydrojasmonate synthesis
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The invention discloses a method for preparing amyl cyclopentenone through organic solvent-free isomerization in methyl dihydrojasmonate synthesis. The method comprises: stirring and mixing p-toluenesulfonic acid and acetic anhydride in a reactor, heating to a temperature of 120 +/-2 DEG C while stirring, adding pentylidene cyclopentanone in a dropwise manner, carrying out thermal insulation stirring for 2-4 h at a temperature of 118-122 DEG C after the adding, cooling after the reaction is finished, regulating the pH value of the reaction solution to 7.5-9 by using a sodium carbonate solution, and carrying out standing layering to obtain an oil phase, wherein the oil phase is crude amyl cyclopentenone. According to the present invention, during the isomerization, no organic solvent is used so as to achieve clean and environmentally-friendly production.
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Paragraph 0013-0015
(2020/01/03)
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- Preparation method of methyl dihydrojasmonate
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The invention discloses an efficient synthesis method of methyl dihydrojasmonate. Under catalysis of homogeneous rhodium and organic nitric oxide, 1-heptyne and ethylene have Pauson-Khand reaction, 2-amyl-2-cyclopentenone is rapidly and efficiently obtained, and an intermediate is subjected to addition and decarboxylation by dimethyl malonate to obtain the methyl dihydrojasmonate. The efficient synthesis method mainly has the advantages that 1-heptyne and ethylene Pauson-Khand reaction yield is effectively improved by the aid of the organic nitric oxide, and usage of rhodium catalysts is reduced. Compared with a traditional methyl dihydrojasmonate production method, the method has the advantages that route steps are short, atom economy is high, the cost is low, and the method is suitable for scale production of the methyl dihydrojasmonate.
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Paragraph 0026; 0027; 0056; 0057; 0060; 0062
(2018/05/01)
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- Chemo-Enzymatic Oxidative Rearrangement of Tertiary Allylic Alcohols: Synthetic Application and Integration into a Cascade Process
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A chemo-enzymatic catalytic system, comprised of Bobbitt's salt and laccase from Trametes versicolor, allowed the [1,3]-oxidative rearrangement of endocyclic allylic tertiary alcohols into the corresponding enones under an Oxygen atmosphere in aqueous media. The yields were in most cases quantitative, especially for the cyclopent-2-en-1-ol or the cyclohex-2-en-1-ol substrates without an electron withdrawing group (EWG) on the side chain. Transpositions of macrocyclic alkenols or tertiary alcohols bearing an EWG on the side chain were instead carried out in acetonitrile by using an immobilized laccase preparation. Dehydro-Jasmone, dehydro-Hedione, dehydro-Muscone and other fragrance precursors were directly prepared with this procedure, while a synthetic route was developed to easily transform a cyclopentenone derivative into trans-Magnolione and dehydro-Magnolione. The rearrangement of exocyclic allylic alcohols was tested as well, and a dynamic kinetic resolution was observed: α,β-unsaturated ketones with (E)-configuration and a high diastereomeric excess were synthesized. Finally, the 2,2,6,6-tetramethyl-1-piperidinium tetrafluoroborate (TEMPO+BF4?)/laccase catalysed oxidative rearrangement was combined with the ene-reductase/alcohol dehydrogenase cascade process in a one-pot three-step synthesis of cis or trans 3-methylcyclohexan-1-ol, in both cases with a high optical purity. (Figure presented.).
- Brenna, Elisabetta,Crotti, Michele,De Pieri, Matteo,Gatti, Francesco G.,Manenti, Gabriele,Monti, Daniela
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supporting information
p. 3677 - 3686
(2018/06/04)
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- DEHYDROGENATION REACTION
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The present invention relates to the field of organic synthesis and more specifically it concerns a process for the dehydrogenation of compound of formula (I) catalyzed by palladium (Pd0) in elemental metallic form.
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Page/Page column 11-12
(2018/04/02)
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- METHODS OF PREPARING a,?-UNSATURATED OR a-HALO KETONES AND ALDEHYDES
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Copper(II) bromide mediated oxidation of acylated enol and use of the reaction in the synthesis of α,β-unsaturated or α-bromo ketones or aldehydes are disclosed. The method provides an efficient and practical process for manufacturing dehydrohedione (DHH) and many other versatile α,β-unsaturated or α-bromo ketones or aldehydes in large scales to avoid using precious metal compounds.
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Paragraph 0087; 0116; 0117; 0120; 0121-0123
(2017/07/14)
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- CIRCULAR ECONOMY METHODS OF PREPARING UNSATURATED COMPOUNDS
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Methods of preparing unsaturated compounds or analogs through dehydrogenation of corresponding saturated compounds and/or hydrogenation of aromatic compounds are disclosed.
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Paragraph 0068
(2018/01/18)
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- Method for synthesizing (1R,2S)-methyl dihydrojasmonate
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The invention discloses a novel method for synthesizing (1R,2S)-methyl dihydrojasmonate by using an asymmetric Michael addition reaction. The method comprises the steps: firstly, subjecting cyclopentanone, which serves as a starting raw material, to an aldol reaction with n-valeraldehyde under alkaline conditions to produce 2-pentylidene cyclopentanone 2, and then, carrying out double-bond transposition under acidic conditions, so as to obtain 2-n-pentyl-2-cyclopentenone 3; then, carrying out a Michael addition reaction with dimethyl malonate in the presence of a chiral amino-acid lithium salt, and carrying out silicagel-column chromatographic separation twice, so as to obtain (1S,2S)-2-n-pentyl-3-dimethyl malonate cyclopentanone 4; and finally, carrying out a hydrolyzed decarboxylation reaction, thereby obtaining (1R,2S)-methyl dihydrojasmonate. According to the method, the synthesis route is simple and direct, the reaction conditions are mild, and the target compound can be prepared by only four-step reactions.
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- Method for one-step synthesis of 2-amyl-2-cyclopentenone
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The invention provides a method for one-step synthesis of 2-amyl-2-cyclopentenone. The method is characterized by comprising the steps of dropwise adding a mixed solution of n-valeraldehyde and cyclopentanone to alkali liquor containing a composite catalyst in a mixed gas atmosphere, and synthesizing 2-amyl-2-cyclopentenone through one-step reaction, wherein the mixed gas is the mixed gas of nitrogen and hydrogen. According to the method, 2-amyl-2-cyclopentenone is synthesized through a one-step method, the total yield is high, the cost of raw materials and auxiliary materials is relatively low, the conversion rate of n-valeraldehyde is 99.4%-99.8%, the selectivity is 87.23%-90.68%, and the yield of 2-amyl-2-cyclopentenone is 87.05%-90.5%. The used composite catalyst can be applied for more than 25-40 times. According to the method, byproducts are few, the prepared product is high in purity, the generated wastewater is relatively less, and the environment is protected.
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Paragraph 0059-0062
(2017/08/16)
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- α,β-Unsaturated ketones via copper(II) bromide mediated oxidation
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A protocol for effecting a rapid Saegusa-type oxidation of enol acetates is reported. This new method relies on the in situ elimination of an α-bromo intermediate to generate α,β-unsaturated ketones using copper(II) bromide. The methodology developed was applied to a range of substrates including a cyclohexanone, which could be directly converted to the corresponding phenol derivative. A catalytic system in which a non-masked ketone was successfully oxidised using substoichiometric CuBr2 was also developed as a proof of principle.
- Sharley, James S.,Collado Pérez, Ana María,Ferri, Estela Espinos,Miranda, Amadeo Fernandez,Baxendale, Ian R.
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supporting information
p. 2947 - 2954
(2016/05/19)
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- Method of manufacturing methylcyclopentanone deriv. (by machine translation)
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PROBLEM TO BE SOLVED: To provide an efficient method for producing a cyclopentanone derivative usable as an intermediate for a methyl (3-oxocyclopentyl)acetate derivative useful as a perfumery material.SOLUTION: The method for producing the cyclopentanone derivative expressed by general formula (III) comprises Michael addition reaction of a 2-cyclopenten-1-one derivative and an ester compound in the presence of a solid base catalyst containing a phosphazene base or a guanidine base. In the formula, Ris a 1-10C hydrocarbon group; Ris 1-4C alkyl; and Ris 1-4C alkyl or alkoxyl.
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- A highly selective aldol condensation of cyclopentanone with valeraldehyde over hydrotalcite-type catalysts
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The aldol condensation using cyclopentanone with valeraldehyde was conducted at hydrotalcites catalysis. The catalyst was obtained by calcining the hydrotalcite precursor (Mg/Al = 3:1) at 773 K. Its reaction performance was evaluated on the various molar ratios of cyclopentanone to n-valeraldehyde. A good catalytic selectivity of 90 % and a high conversion of 93 % were achieved under mild conditions.
- Xu,Cao,Ma,Peng
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p. 3847 - 3849
(2013/05/22)
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- Oxidative conversion of silyl enol ethers to α,β-unsaturated ketones employing oxoammonium salts
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The oxidative conversion of silyl enol ethers to α,β-unsaturated ketones using a less-hindered class of oxoammonium salts (AZADO +BF4-) is described. The reaction proceeds via the ene-like addition of oxoammonium salts to silyl enol ethers.
- Hayashi, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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supporting information; experimental part
p. 154 - 157
(2012/02/16)
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- METHOD FOR PRODUCING OF 2-ALKYL-2-CYCLOALKEN-1-ONE
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The present invention relates to [1] a process for producing a 2-alkyl-2-cycloalken-1-one represented by the following general formula (2), which includes the step of subjecting a 2-(1-hydroxyalkyl)cycloalkan-1-one to dehydration and isomerization in the co-existence of an acid and a platinum group metal catalyst, and [2] a process for producing an alkyl(3-oxo-alkylcycloalkyl)acetate which is useful as a perfume material, using the 2-alkyl-2-cycloalken-1-one: wherein n is an integer of 1 or 2; and R1 and R2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms with the proviso that R1 and R2 may form a ring through a carbon atom adjacent thereto.
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- PROCESS FOR PRODUCING A 2-ALKYL-2-CYCLOALKENE-1-ONE
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The present invention relates to a process for producing a 2-alkyl-2-cycloalken-1-one represented by the following general formula (2), including the step of reacting a 2-alkylidene cycloalkanone in the presence of a palladium and/or platinum catalyst which is treated in the following steps (a) and (b); and a method for activating the palladium and/or platinum catalyst including the following steps (a) and (b): Step (a): activating the palladium and/or platinum catalyst in an atmosphere containing a hydrogen gas; and Step (b): replacing the hydrogen gas being present as the atmosphere for the catalyst in the step (a), with an inert gas to remove the hydrogen gas out of the reaction system, wherein m is 0 to 3; n is 1 or 2; R1 and R2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; and R3 is an alkyl group having 1 to 5 carbon atoms. In accordance with the present invention, the 2-alkyl-2-cycloalken-1-one can be produced with a high purity and a high productivity.
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Page/Page column 8
(2011/01/12)
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- METHOD FOR PRODUCING OF 2-ALKYL-2-CYCLOALKEN-1-ONE
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The present invention relates to [1] a process for producing a 2-alkyl-2-cycloalken-1-one represented by the following general formula (2), which includes the step of subjecting a 2-(1-hydroxyalkyl)cycloalkan-1-one to dehydration and isomerization in the co-existence of an acid and a platinum group metal catalyst, and [2] a process for producing an alkyl(3-oxo-alkylcycloalkyl)acetate which is useful as a perfume material, using the 2-alkyl-2-cycloalken-1-one: wherein n is an integer of 1 or 2; and R1 and R2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms with the proviso that R1 and R2 may form a ring through a carbon atom adjacent thereto.
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Page/Page column 11-12
(2011/01/12)
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- Synthesis of functionalized resorcinols by rhodium-catalyzed [5+1] cycloaddition reaction of 3-acyloxy-1,4-enynes with CO
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A novel [5+1] type carbonylative cycloaddition reaction has been developed using a Rh complex as catalyst. This reaction can convert readily available 3-acyloxy-1,4-enynes and CO to a wide range of functionalized resorcinols in good yields. A mechanism involving Rh-catalyzed cyclocarbonylation of 3-acyloxy-1,4-enynes accompanied by a 1,2-acyloxy shift is proposed for the present [5+1] type cycloaddition reaction. The Royal Society of Chemistry 2010.
- Brancour, Celia,Fukuyama, Takahide,Ohta, Yuko,Ryu, Ilhyong,Dhimane, Anne-Lise,Fensterbank, Louis,Malacria, Max
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supporting information; experimental part
p. 5470 - 5472
(2010/09/18)
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- Cycloalkanone composition
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The present invention relates to a cycloalkanone composition which contains cycloalkanone (1) in an amount of 70 wt% or more based on the composition, wherein the content of a dimer of a cycloalkanone represented by formula (2) is 0.055 or less in terms of weight ratio to the cycloalkanone (1), a process for producing the same, a process for producing a composition containing alkyl acetate (5) by using the cycloalkanone composition, and an alkyl acetate composition obtained by the process wherein n is an integer of 1 or 2, R1 and R2 each represent H, a C1 to C8 alkyl group etc., and R3 represents a C1 to C3 alkyl group.
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Page/Page column 5
(2008/06/13)
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- Method of producing acetate derivative
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The present invention relates to a method of producing an acetate derivative represented by the formula (II) by demonocarboxylating dimalonate represented by the formula (I), wherein water is supplied while the concentration of water in a demonocarboxylating reaction solution is controlled to 0.4% by weight or less to run demonocarboxylation: wherein n denotes an integer of 1 or 2, R1 and R2 represent H, a C1-8 alkyl group or the like and R3 represents a C1-3 alkyl group.
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Page/Page column 6
(2008/06/13)
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- Process for producing cycloalkanone derivatives
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The present invention provides a process for producing 2-(1-hydroxyalkyl)cycloalkanone and/or 2-(1-hydroxyaryl)cycloalkanone in high yield and selectivity, as well as a process using the same to produce a cycloalkanone derivative useful as a perfume material and a physiologically active substance. Disclosed is a process for producing compound (3), which includes subjecting a cycloalkanone, and aldehyde (2) containing carboxylic acid (1), to aldol condensation in the presence of water and a basic catalyst, wherein the molar amount (referred to hereinafter as A) of the basic catalyst added is not less than the molar amount (referred to hereinafter as B) of the carboxylic acid (1) contained in the aldehyde (2) and the difference between A and B, that is, (A - B) is 0.06 mol or less per mol of the aldehyde (2) , as well as a process for producing compounds (7) and (8) by using the compound (3) obtained by the above process.
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- A Pauson-Khand-type reaction between alkynes and olefinic aldehydes catalyzed by rhodium/cobalt heterobimetallic nanoparticles: An olefinic aldehyde as an olefin and CO source
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Co/Rh (Co:Rh = 2:2) heterobimetallic nanoparticles derived from Co 2Rh2(CO)12 react with alkynes and α,β-unsaturated aldehydes such as acrolein, crotonaldehyde, and cinnamic aldehyde and release products resulting from [2 + 2 + 1]cycloaddition of alkyne, carbon monoxide, and alkene. α,β-Unsaturated aldehydes act as a CO and alkene source. These reactions produce 2-substituted cyclopentenones.
- Park, Kang Hyun,Jung, Il Gu,Chung, Young Keun
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p. 1183 - 1186
(2007/10/03)
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- Method for producing 2-(alkyl)cycloalkenone
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A method for producing 2-(alkyl)cycloalkenone and a method for producing alkyl(3-oxo-2-alkylcycloalkyl) acetate and 5-alkyl-5-alkanolide which are useful as flavoring materials and physiologically active substances using the same are provided. A method for producing Compound (2) including the steps of: dehydrating Compound (1) using an acid catalyst until the conversion ratio of dehydration reaction reaches 20 to 90% based on Compound (1), thereby obtaining a mixture containing Compound (1) and Compound (3); and isomerizing Compound (3) while dehydrating the remaining Compound (1), and a method for producing Compound (5) or (6) using obtained Compound (2).
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- Process for producing 2-alkyl-2cyclopentenones
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Industrially advantageous processes for producing a 2-alkyl-2-cyclopentenone in high yields starting from a 2-(1-hydroxyalkyl)cyclopentanone or a 2-alkylidenecyclopentanone, which are obtainable from a cyclopentanone and a carbonyl compound. A 2-(1-hydroxyalkyl)cyclopentanone represented by the following general formula (1): (wherein R1, R2, R3, R4, R5, R6 and R7 each independently represents hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have one or more substituents or an aromatic group which may have one or more substituents, and each of (1) R6 or R7 with R3 and (2) R6 or R7 with R4 or R5 may be together combined to form a ring which may have a double bond) is subjected to dehydrative isomerization in the presence of a bromine compound and/or an iodine compound.
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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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- The utility of vinyl ethers and vinyl esters in the Khand reaction. The value of vinyl esters as ethylene equivalents and a modified synthesis of (+)-taylorione as an example
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The behaviour of various oxygenated alkenes in the Khand cyclisation reaction has been studied. Although several vinyl ethers reacted to give the expected oxygenated cyclopentenone products, usually with good levels of regioselectivity, the use of vinyl esters was found to afford, as the major products, reduced cyclopentenones in which the carbon-oxygen bond had been cleaved. This unexpected reaction was developed into an alternative procedure to using ethylene gas in the Khand reaction and was found to be applicable with a variety of alkyne substrates. The method was then extended to form the key step in the synthesis of the natural product (+)-taylorione (and (+)-nortaylorione).
- Kerr, William J.,McLaughlin, Mark,Pauson, Peter L.,Robertson, Sarah M.
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p. 104 - 117
(2007/10/03)
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- Method for producing jasmonate derivatives and intermediates thereof
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The present invention provides a method for efficiently producing a 2-alkyl-2-cyclopentenone as well as a method for producing a jasmonate derivative by using the same. That is, in the present invention, the compound (2) is obtained by reacting an amine and a hydrogen halide with the compound (1) at a specific ratio to carry out isomerization reaction or by reacting a catalyst comprising an amine and a hydrogen halide with the compound (3) to carry out dehydration-isomerization reaction. Further, this compound (2) is reacted with a malonic acid diester and then reacted with water to obtain a jasmonate derivative (5): wherein each of R1 and R2 represents H, a C1-8 alkyl group or the like, and R3 represents a C1-3 alkyl group.
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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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- Development of modified Pauson-Khand reactions with ethylene and utilisation in the total synthesis of (+)-taylorione
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Two complementary Pauson-Khanol annulation protocols for use with the gaseous alkene, ethylene, are described. These N-oxide promoted reactions (10 examples) are shown to proceed under both mild autoclave condition or, more conveniently, at atmospheric pressure. The developed methodology has been utilised as the key transformation in the total synthesis of the sesquiterpene (+)-taylorione which has been realised in a good overall yield from readily available (+)-2-carene.
- Donkervoort, Johannes G.,Gordon, Alison R.,Johnstone, Craig,Kerr, William J.,Lange, Udo
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p. 7391 - 7420
(2007/10/03)
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- A CONVENIENT METHOD FOR THE PRODUCTION OF 2-SUBSTITUTED 2-CYCLOPENTEN-1-ONES FROM ALKYL (ALKENYL) 2-CHLOROCYCLOPROPYL KETONES
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2-Substituted 2-cyclopenten-1-ones were obtained with good yields by the reaction of the respective 2-chlorocyclopropyl ketones with an aqueous solution of sodium hydroxide.
- Kulinkovich, O. G.,Sorokin, V. L.
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p. 196 - 197
(2007/10/02)
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- Vinylsilane-terminated cycloacylation: A general synthetic approach to four- to six-membered cyclic ketones and its regiochemical features
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Intramolecular acylations of m-trimethylsilyl-m-alkenoyl chlorides (m = 4 and 5) are described which afford the expected α-alkylidenecycloalkanone and/or the unexpected cycloalkenone, depending markeldy upon the substitution pattern on the vinylsilane moiety and/or the chain length (m).
- Kishi,Mikami,Nakai
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p. 8111 - 8118
(2007/10/02)
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- Process for preparing oxocyclopentene derivatives
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A process for preparing oxocyclopentenes of the formula: STR1 wherein R1 is hydrogen, lower alkyl or lower alkenyl and R2 is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, substituted or unsubstituted aryl, ar(lower)alkyl, thienyl or cycloalkyl, which comprises subjecting a furan-carbinol of the formula: STR2 wherein R1 is as defined above and R3 is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, substituted or unsubstituted aryl, ar(lower)alkyl, thienyl or cycloalkyl to rearrangement, subjecting the resultant hydroxycyclopentenone of the formula: STR3 wherein R1 and R3 are each as defined above to hydrogenation and subjecting the resulting hydroxycyclopentanone of the formula; STR4 wherein R1 and R2 are each as defined above to dehydration.
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- Syntesis of 2-Cycloalken-1-ones
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The bromination of 2-alkyl- and 2-phenyl-1-cycloalkanones with N-bromosuccinimide and subsequent dehydrobromination with aniline gave the corresponding 2-cycloalken-1-ones.
- Shimazaki, Makoto,Huang, Zhi-Hui,Goto, Mikiko,Suzuki, Noriko,Ohta, Akihiro
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p. 677 - 678
(2007/10/02)
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- Potassium Fluoride on Alumina - a Versatile Reagent for Isomerisation of Olefins
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Olefins undergo smooth isomerization to the thermodynamically more stable form on treatment with potassium fluoride coated on alumina.
- Radhakrishna, A.S.,Suri, S.K.,Rao, K.R.K.Prasad,Sivaprakash, K.,Singh, B.B.
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p. 345 - 348
(2007/10/02)
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- ORGANOTIN HOMOENOLATE EQUIVALENTS - ACCESS TO β-ACYL- AND β-ARYL-PROPIONALDEHYDES THROUGH HETEROSUBSTITUTED ALLYLTINS AND VINYLTINS
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Although, α-ethoxycrotyltributyltin can be used as an equivalent of the homoenolate anion CH3-CHCH2CHO in reactions with acyl chlorides, the non-substituted α-ethoxyallyltributyltin could not be employed in this way. γ-Methoxyvinyltins, easily prepared by hydrostannation of propargylic ethers, are successfully employed as synthetic equivalents of the homoenolate anions -CH2CH2CHO and -CH2CH2COCH3 in reactions with acyl chlorides.A silylated γ-methoxyvinyltin, which is both a vinyltin and an allylsilane, reacts with acyl chlorides and aryl bromides as a promising equivalent of the homoenolate anion -CH2CH2CHO and tolerates a wide range of other reactive functional groups.
- Verlhac, Jean-Baptiste,Pereyre, Michel,Quintard, Jean-Paul
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p. 6399 - 6412
(2007/10/02)
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- Synthesis of 2-Alkyl-2-cyclopenten-1-ones. A Versatile Kinetic Alkylation-Ozonolysis Procedure for the Preparation of γ-Ketoaldehydes
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A range of 2-alkyl-2-cyclopenten-1-ones including the prostaglandin precursor 2-(6-methoxycarbonylhexyl)-2-cyclopenten-1-one and the jasmonoid precursor 2--2-cyclopenten-1-one, have been prepared by a short synthetic route which begins with 6-methyl-5-hepten-2-one and generates the key 1,4-ketoaldehyde intermediates by a kinetic alkylation-ozonolysis procedure.
- Geraghty, Niall W. A.,Morris, Noreen M.
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p. 603 - 607
(2007/10/02)
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- The effect of ultrasound and of phosphine and phosphine-oxides on the Khand reaction
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Ultrasonic irradation allows the Khand reaction to be conducted rapidly at low temperatures.Addition of phosphine oxides to the reaction mixture significantly increases yields in most cases.
- Billington, David C.,Helps, I. Malcolm,Pauson, Peter L.,Thomson, William,Willison, Debra
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p. 233 - 242
(2007/10/02)
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- A NEW FACILE SYNTHESIS OF 2-ALKYLCYCLOPENT-2-ENONES
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A new, simple and short route to 2-alkylcyclopent-2-enones starting from inxpensive terminal epoxides is described.
- Bonsignore, S.,Dalcanale, E.,Martinengo, T.
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p. 2241 - 2250
(2007/10/02)
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- SYNTHESIS WITH MANGANIC SALTS; PART III: SYNTHESIS OF 1,4-DIKETONES THROUGH MANGANIC ACETATE-MEDIATED ADDITION OF KETONE TO ISOPENTENYL SULFONES. ACETOXYLATION OF Β,Γ-UNSATURATED KETONES BY MANGANOUS AND CUPRIC ACETATES
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Conditions have been found to selectively add ketones to isopentenyl sulfones.The major product, a ketone bearing a methylene group at the γ position, gave upon ozonolysis the corresponding 1,4-diketone.The usefulness of the overall process was illustrated by the efficient syntheses of jasmone and of one half of pyrenophorine.The γ-acetoxy conjugated enones that invariably formed during these additions resulted from the oxidation of an isomeric β,γ-unsaturated ketone by manganous and cupric acetates.Such an acetoxylation has been used to prepare 6β-acetoxy-cholestenone from cholesterol and also to prepare chrysanthemic acid.
- Breuilles, Pascal,Uguen, Daniel
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p. 705 - 720
(2007/10/02)
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- A Regioselective Synthesis of Cyclopentenones from 4-Thianone
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Alkyl-substituted 3-cyclopentenones 4 and 5 were prepared in moderate to good yields starting from 4-thianone by the selective alkylation and Ramberg-Baecklund-type reactions.One route starts with 6-alkyl-1,4-dioxa-8-thiaspirodecane 8,8-dioxides (8) and another with 7-alkyl-1,4-dioxa-7-(p-tolylsulfonyl)-8-thiaspirodecane 8,8-dioxides (15), followed by acid-catalyzed cleavage of the 1,3-dioxolane ring of 1,4-dioxaspironon-7-enes 9 and 16 to afford 4 and 5.
- Matsuyama, Haruo,Miyazawa, Yasuyuki,Takei, Yuji,Kobayashi, Michio
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p. 1703 - 1710
(2007/10/02)
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- A CONVENIENT METHOD FOR THE PREPARATION OF 1-ACETOXY-1-METHOXY-4-ALKANONES
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1-Acetoxy-1-methoxy-4-alkanones were obtained by the action of acetic acid on ethereal solutions of the corresponding alkyl trans-2-methoxycyclopropyl ketones. 1-Acetoxy-1-methoxy-4-decanone synthesized by this method was converted by the action of aqueous sodium hydroxide to 2-amyl-2-cyclopentenone in good yield.
- Kulinkovich, O. G.,Tishchenko, I. G.,Romashin, Yu. N.,Zaitsev, Yu. A.
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p. 1064 - 1067
(2007/10/02)
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- AN EFFICIENT SYNTHETIC METHOD OF METHYL (+/-)-JASMONATE
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An efficient synthetic method of methyl (+/-)-jasmonate is described. 2-Pentynyl-2-cyclopentenone, the key intermediate in this route, was synthesized by applying the palladium-catalyzed enone formation from allyl β-keto carboxylate as a key reaction.
- Kataoka, Hideaki,Yamada, Toshiro,Goto, Kuniaki,Tsuji, Jiro
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p. 4107 - 4112
(2007/10/02)
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- 1,4-Ketoaldehydes via Michael-Addition of deprotonated Aldimines to 2-(N-Methylanilino)-acrylonitrile
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A new method for the synthesis of the title compounds by a one-pot three component coupling reaction is described.It consists of the reaction of an enolateanion- and an enolcation-equivalent with subsequent alkylation of an acylanion-equivalent.
- Ahlbrecht, Hubertus,Daacke, Axel von
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