- Vapor-phase intramolecular aldol condensation of 2,5-hexanedione to 3-methylcyclopent-2-enone over ZrO2-supported Li2O catalyst
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Vapor-phase intramolecular aldol condensation of 2,5-hexanedione to produce 3-methylcyclopent-2-enone was performed over several ZrO2-supported alkali and alkali earth metal oxides. Among the tested catalysts, ZrO2-supported Li2O showed a stable catalytic activity. A high 2,5-hexanedione conversion of 99% with a 3-methylcyclopent-2-enone selectivity of 96% was achieved over a 20?mol% Li2O-loaded ZrO2catalyst at 250?°C.
- Sun, Daolai,Chiba, Shigenori,Yamada, Yasuhiro,Sato, Satoshi
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Read Online
- Total synthesis of jiadifenolide
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As a potent neurotrophic agent, the sesquiterpenoid jiadifenolide represents a valuable small-molecule lead for the potential therapeutic treatment of neurodegenerative diseases. A stereocontrolled total synthesis of this densely functionalized natural product is reported, central to which is an adventurous samarium-mediated cyclization reaction to establish the tricyclic core and the adjacent C5 and C6 quaternary stereocenters.
- Paterson, Ian,Xuan, Mengyang,Dalby, Stephen M.
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Read Online
- Synthesis of Bio-Based Methylcyclopentadiene from 2,5-Hexanedione: A Sustainable Route to High Energy Density Jet Fuels
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The sustainable, bio-based, platform chemical, 2,5-hexanedione [HD (1)], was efficiently converted to methylcyclopentadiene [MCPD (4)] through a three-step process consisting of intramolecular aldol condensation, catalytic chemoselective hydrogenation, and dehydration. Base-catalyzed aldol condensation of 1 resulted in the formation of 3-methyl-2-cyclopenten-1-one [MCO (2)], which was then converted to 3-methyl-2-cyclopenten-1-ol [MCP (3)] by chemoselective reduction with a ternary Ru catalyst system [RuCl2(PPh3)3/NH2(CH2)2NH2/KOH]. The hydrogenation proceeded with 96 % chemoselectivity. 3 was then dehydrated over AlPO4/MgSO4 at 70 °C under reduced pressure to yield 4, which can undergo an ambient temperature [4+2]-Diels-Alder cyclization to generate dimethyldicyclopentadiene (DMDCPD), a commodity chemical useful for the preparation of high-performance fuels and polymers. Through this approach, advanced jet fuels and materials can be conveniently produced from sustainable cellulosic feedstocks.
- Woodroffe, Josanne-Dee,Harvey, Benjamin G.
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Read Online
- Tantalum vs Niobium MCF nanocatalysts in the green synthesis of chromene derivatives
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TaMCF silicas modified with alkaline metals can be considered a novel family of highly efficient bifunctional catalysts involved in the synthesis of chromene derivatives, from salicylaldehyde 2 and acetonitrile compounds, under mild conditions, showing enhanced catalytic performance than their NbMCF analogues. The observed reactivity was mainly attributed to the higher basicity of the Me/TaMCF but also the texture of the samples. The Me/TaMCF silicas showed higher Br?nsted basicity than the Nb ones as indicated by the stronger interaction between alkali metals and Ta in the UV–vis and the test reaction experiments. On the other hand, the basicity of Me/TaMCF together the reactivity degree and steric hindrance of the starting acetonitriles are key factors influencing the reaction selectivity. In conclusion, the basicity of the samples plays an important role initiating the reaction by activation of nucleophile but also a compromise between alkaline cation size and basicity is required.
- Smuszkiewicz, Agata,López-Sanz, Jesús,Sobczak, Izabela,Martín-Aranda, Rosa M.,Ziolek, Maria,Pérez-Mayoral, Elena
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- Calcium and nitrogen species loaded into SBA-15-a promising catalyst tested in Knoevenagel condensation
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Mesoporous silica of the SBA-15 type was used as a support for basic active centers generated by the incorporation of calcium species and (3-aminopropylo)trimethoxysilane (APTMS) or imidazole. The samples were characterized by low temperature N2 adsorption/desorption, XRD, XPS, FTIR spectroscopy, CO2-TPD, and elemental and thermal analyses. Calcium containing samples were analysed in 2,5-hexanedione dehydration and cyclization, while the activities of all the samples were examined in Knoevenagel condensation between benzaldehyde and malononitrile. It was demonstrated that the calcium species interacted with a silica support increasing the stabilization of organosilanes on the SBA-15 surface. A very high activity of the catalysts in Knoevenagel condensation indicated a synergistic interaction between calcium and the organic modifiers.
- Kryszak, Dorota,Stawicka, Katarzyna,Trejda, Maciej
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Read Online
- Transformation of γ-ketoaldehyde acetals into 3-substituted-2-cyclopentenones via cyanophosphates under mild conditions
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The reaction of cyanophosphates, which are readily derived from γ-ketoaldehyde acetals, with TMSN3 (3 eq)/Bu2SnO (0.3 eq) in refluxing toluene directly furnished 3-substituted-2-cyclopentenones in modest to good yield under mild conditions. The present method was further applied toward the synthesis of dechlorotrichodenone C isolated from Trichoderma asperellum.
- Yoneyama, Hiroki,Takatsuji, Kumi,Ito, Aiko,Usami, Yoshihide,Harusawa, Shinya
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- Tris(2-aminoethyl)amine/metal oxides hybrid materials—preparation, characterization and catalytic application
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Three different metal oxides (basic MgO, basic-acidic Al2O3 and acidic-basic Nb2O5) characterized by comparable surface areas (MgO—130 m2/g; Al2O3—172 m2/g and Nb2O5—123 m2/g) and pore systems (domination of mesopores with narrow pore size distribution) were modified with tris(2-aminoethyl)amine (TAEA) via two methods: (i) direct anchoring of amine on metal oxide and (ii) anchoring of amine on metal oxide functionalized with (3-chloropropyl)trimethoxysilane. The obtained hybrid materials were characterized in terms of effectiveness of modifier anchoring (elemental analysis), their structural/textural properties (nitrogen adsorption/desorption, XRD), acidity/basicity of support (2-propanol dehydration and dehydrogenation, dehydration and cyclization of 2,5-hexanedione), states of modifier deposited on supports (XPS, FTIR, UV–VIS) and the strength of interaction between the modifier and the support (TG/DTG). It was evidenced that acidic-basic properties of metal oxides as well as the procedure of modification with TAEA determined the ways of amine anchoring and the strength of its interaction with the support. The obtained hybrid materials were tested in Knoevenagel condensation between furfural and malononitrile. The catalysts based on MgO showed superior activity in this reaction. It was correlated with the way of TAEA anchoring on basic MgO and the strength of modifier anchoring on the support. To the best of our knowledge tris(2-aminoethyl)amine has not been used as a modifier of solid supports for enhancement of the catalyst activity in Knoevenagel condensation.
- Stawicka, Katarzyna,Ziolek, Maria
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- Producing methylcyclopentadiene dimer and trimer based high-performance jet fuels using 5-methyl furfural
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Methylcyclopentadiene dimer and trimer based fuels are synthesized from 5-methyl furfural for the first time with yields as high as 74.4%. They exhibit both high density and high thermal stability that are better than those of widely used fossil based jet fuels such as JP-10 and JP-7, and represent types of high-performance fuels. This work also provides a potential and scale-up feasible route for synthesizing high-performance jet fuels from biomass.
- Dai, Yiying,Liu, Qing,Liu, Yakun,Liu, Yanan,Ma, Chi,Nie, Genkuo,Pan, Lun,Shi, Chengxiang,Zhang, Xiangwen,Zou, Ji-Jun
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p. 7765 - 7768
(2020/12/01)
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- Preparation method of 3-methyl-2-cyclopentene-1-one
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The invention provides a preparation method of 3-methyl-2-cyclopentene-1-one. A device comprises a coiled tube type reactor and two plunger pumps, the output ends of the plunger pumps are connected with the coiled tube type reactor, and the coiled tube type reactor is placed in an oil bath pan at 120-130 DEG C. The preparation method comprises the following steps: S1, preparing a 2, 5-hexanedioneaqueous solution and a 20% sodium hydroxide solution; S2, respectively immersing the plunger pumps into the 2, 5-hexanedione aqueous solution and the 20% sodium hydroxide solution, and setting the flow rate to be 10-18 mL/min; and S3, placing a 1 L four-necked bottle at the outlet of the reactor, cooling with heat-conducting oil at the temperature of 0-5 DEG C in an external bath, stopping the reaction and sampling after receiving the reaction liquid for 30 minutes, extracting with acetic acid, and carrying out GC analysis. According to the invention, a continuous reaction technology is adopted, and the reaction selectivity is regulated by adjusting the molar ratio, the feeding rate and the residence time of materials; and the reaction solution is collected and cooled after the reaction isfinished, thereby avoiding the quick decomposition of the product in the hot alkali liquor. Water is used as a solvent, and reaction is carried out at a low temperature, so environmental pollution isreduced, and energy consumption is reduced. And the yield of the prepared 3-methyl-2-cyclopentene-1-one reaches 70-75%.
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Paragraph 0023-0025; 0028-0038; 0045-0054; 0056-0063
(2020/12/15)
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- Production of oxygen-containing alicyclic compounds (by machine translation)
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[Problem] to provide, in a one-step reaction synthesizes an alicyclic compound containing oxygen, high yield production of oxygen-containing compound is a cycloaliphatic. [Solution] one or more hydroxy or carbonyl group 2, or a hydroxyl group having the carbon number of 5 or more aliphatic carbonyl group 2 in accordance with one or more oxygen-containing compound, a basic catalyst is brought into contact with an oxygen-containing alicyclic compound by cyclodehydration reaction, oxygen-containing alicyclic compound. [Drawing] no (by machine translation)
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Paragraph 0035; 0037; 0038
(2020/04/24)
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- Preparation method of alkyl-substituted tetrahydrodicyclopentadiene dimers and application thereof as jet fuel (by machine translation)
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The invention discloses a preparation method of a hanging type tetrahydroalkyl substituted dicyclopentadiene dimer or a mixture thereof, and the preparation :(1) method of the hanging type tetrahydroalkyl substituted ;(2) dicyclopentadiene dimers or mixtures thereof according to ;(3) the invention has the advantages that the prepared hanging ;(4) type tetrahydroalkyl substituted dicyclopentadiene dimers or mixtures thereof are higher in heat sinking. value and lower in viscosity . (by machine translation)
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Paragraph 0048-0052
(2019/12/25)
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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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- Coupling of Methanol and Carbon Monoxide over H-ZSM-5 to Form Aromatics
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The conversion of methanol into aromatics over unmodified H-ZSM-5 zeolite is generally not high because the hydrogen transfer reaction results in alkane formation. Now circa 80 % aromatics selectivity for the coupling reaction of methanol and carbon monoxide over H-ZSM-5 is reported. Carbonyl compounds and methyl-2-cyclopenten-1-ones (MCPOs), which were detected in the products and catalysts, respectively, are considered as intermediates. The latter species can be synthesized from the former species and olefins. 13C isotope tracing and 13C liquid-state NMR results confirmed that the carbon atoms of CO molecules were incorporated into MCPOs and aromatic rings. A new aromatization mechanism that involves the formation of the above intermediates and co-occurs with a dramatically decreased hydrogen transfer reaction is proposed. A portion of the carbons in CO molecules are incorporated into aromatic, which is of great significance for industrial applications.
- Chen, Zhiyang,Ni, Youming,Zhi, Yuchun,Wen, Fuli,Zhou, Ziqiao,Wei, Yingxu,Zhu, Wenliang,Liu, Zhongmin
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supporting information
p. 12549 - 12553
(2018/09/11)
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- Effect of Cp*Iridium(III) Complex and acid co-catalyst on conversion of furfural compounds to cyclopentanones or straight chain ketones
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In this paper, Cp*Ir (III) Complex and acid co-catalyst system was developed. By using Cp*Ir and γ-Al2O3 (Lewis acid), 5-hydroxymethylfurfural (5-HMF) can be converted efficiently to 3-hydroxymethyl cyclopentanone (HCPN). Meanwhile, Cp*Ir and Br?nsted acid can promote conversion of 5-HMF to 1-Hydroxy-2,5-hexanedione (HHD). The effect of Lewis acid and Br?nsted acid on the hydrogenation of furan derivatives was studied. Mechanism of conversion of 5-HMF to HCPN was discussed in detail and mechanism proposed by our predecessors was revised. Instead of being an intermediate for the formation of HCPN, it is believed that, HHD is a product of another reaction pathway. HHD condensed via Aldol reaction to produce 3-methylcyclopenten-2-ol-1-one (MCP) instead of HCPN. Under the promotion of Lewis acid, 5-HMF firstly convert to the precursor of HHD. After that, the reaction is through 4 π-electrocyclic ring closure process and HCPN was formed ultimately. Furthermore, we found that our Cp*Ir and acid co-catalyst system is suitable for a variety of furfural compounds. By using Cp*Ir, Br?nsted acid can promote conversion of furfural compounds to straight chain ketones and Lewis acid can promote the rearrangement of furfural compounds to cyclopentanone derivatives.
- Xu, Yong-Jian,Shi, Jing,Wu, Wei-Peng,Zhu, Rui,Li, Xing-Long,Deng, Jin,Fu, Yao
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p. 266 - 273
(2017/07/13)
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- 3-methyl-2-cyclopentene-1-ketone catalytic preparation method
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The invention discloses a 3-methyl-2-cyclopentene-1-ketone catalytic preparation method. The method includes steps: step S1, adding 2,5-hexanedione into a weak-polarity organic solvent, adding a solid catalyst, and allowing reaction for 6-10h at 150-250 DEG C; step S2, after reaction is finished, filtering, and drying the solid catalyst for recycling; collecting an organic phase of filtrate, and separating and refining to obtain a target product 3-methyl-2-cyclopentene-1-ketone, wherein the solid catalyst takes modified nano zeolite powder as a carrier and copper nitrate as a precursor to load copper oxide to the modified nano zeolite powder by means of impregnation, drying and calcining. A preparation method of the modified nano zeolite powder includes: dispersing 30-40 parts of nano zeolite powder to into 45-55 parts of triethylene tetramine being 5-15% in mass fraction, stirring for 25-35min at 40-50 DEG C, adding 5-15 parts of Zn(NO3)2.6H2O, stirring for 20-30min, cooling, filtering and drying to obtain the modified nano zeolite powder. The 3-methyl-2-cyclopentene-1-ketone catalytic preparation method is high in conversion rate, and the catalyst is recyclable.
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Paragraph 0021-0074
(2017/12/01)
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- Mesoporous niobiosilicate NbMCF modified with alkali metals in the synthesis of chromene derivatives
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We report the synthesis, characterization and activity of new series of catalysts based on Niobium Mesoporous Cellular Foams (NbMCF), modified with alkaline metal elements. These materials exhibit very different acid-base properties attributed to the Nb source for the preparation of the catalysts and the presence and loading of different alkaline metals. The Me/NbMCF materials (where Me are alkaline metals) were tested in the reaction of 2-hydroxybenzaldehyde and ethyl cyanoacetate, under solvent-free conditions, at room temperature, leading to mixtures of the corresponding chromenes 4 and 5, as mixtures of diastereomers erythro/threo, in a 2:1 ratio, respectively, with good to excellent yields. Our experimental results indicate that the metal loading on the catalysts and the acid-base character, and the texture parameters are probably determining factors in the reactivity and the observed diastereoselectivity. The computational study suggests that the presence of alkaline oxides on Me/NbMCF catalyst, exhibiting strong basicity, activates the formation of the nucleophile species, the corresponding enolate, and initiates the reaction. However, the cation size has a deep impact on the stability of the reactant complex so that the effective aldolization could be obstructed by the presence of the bulkier centers.
- Smuszkiewicz, Agata,Lopez-Sanz, Jesús,Sobczak, Izabela,Ziolek, Maria,Martín-Aranda, Rosa M.,Soriano, Elena,Pérez-Mayoral, Elena
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p. 133 - 142
(2016/09/28)
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- Production of 2,5-hexanedione and 3-methyl-2-cyclopenten-1-one from 5-hydroxymethylfurfural
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A novel approach for the production of 2,5-hexanedione (HDN) and 3-methyl-2-cyclopenten-1-one (3-MCO) from 5-hydroxymethylfurfural (HMF) by water splitting with Zn is reported for the first time. The use of high temperature water (HTW) conditions is the key for the efficient conversion of HMF to HDN and 3-MCO. Parameters regarding the Zn amount, temperature and reaction time are optimized and HDN and 3-MCO are produced in 27.3% and 30.5% yields, respectively. The roles of HTW and ZnO obtained by oxidation of Zn in water for the conversion of HMF, together with intermediate structures, are discussed to understand the mechanism of the reaction.
- Ren, Dezhang,Song, Zhiyuan,Li, Lu,Liu, Yunjie,Jin, Fangming,Huo, Zhibao
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supporting information
p. 3075 - 3081
(2016/06/06)
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- Method for preparing 2,5-hexanedione and 3-methyl cyclopentenone from 5-hydroxymethyl furfural
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The invention provides a method for preparing 2,5-hexanedione and 3-methyl cyclopentenone from 5-hydroxymethyl furfural. The method includes the following steps that after 5-hydroxymethyl furfural, a reducing agent and a solvent are mixed, in an inert atmosphere, a hydrothermal reaction is conducted at the temperature of 100-250 DEG C; after the hydrothermal reaction is completed, the product is subjected to solid-liquid separation, and 2,5-hexanedione and 3-methyl cyclopentenone are harvested. Compared with the prior art, the method has the following advantages that a biomass derivative 5-hydroxymethyl furfural is used as a raw material for synthesizing 2,5-hexanedione and 3-methyl cyclopentenone, 5-hydroxymethyl furfural can be prepared from biomass resource lignocellulose (coming from plants widely existing in the nature), fossil energy does not need to be consumed, and global energy problems at present can be partially relieved.
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Paragraph 0028; 0029; 0030; 0031; 0032
(2016/12/01)
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- Expanding the Scope of the Gold(I)-Catalyzed Rautenstrauch Rearrangement: Protic Additives
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The synthesis of substituted 2-cyclopentenones using a commercially available gold(I) catalyst is described under flexible reaction conditions. During the course of our investigations, we discovered that using a proton source as an additive is required to obtain the desired substituted cyclopentenones in good yields.
- Bürki, Cédric,Whyte, Andrew,Arndt, Sebastian,Hashmi, A. Stephen K.,Lautens, Mark
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supporting information
p. 5058 - 5061
(2016/10/14)
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- Nb and Zr modified MWW zeolites-characterisation and catalytic activity
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Hydrogen forms of MCM-22 and delaminated MCM-56 zeolites were modified with niobium and zirconium species. The structure/texture and surface properties, as well as the catalytic activity for dibutyl sulfide oxidation, of the two types of modified zeolites were compared. The presence of Br?nsted (BAS) and Lewis (LAS) acid sites was detected after pyridine adsorption in all the prepared materials. The highest number of BAS and LAS was observed for HMCM-22. The number of BAS significantly decreased after metal modification because of the interaction between the metal sources and the BAS. External silanol groups of zeolites also participate in metal anchoring. The catalysts obtained were tested for liquid phase dibutyl sulfide oxidation with hydrogen peroxide. The texture of the zeolites and the nature of the metal modifier have a crucial effect on the oxidation of dibutyl sulfide. MCM-56 zeolites are more active than their counterparts of MCM-22 type. Application of niobium containing zeolites significantly increases the reaction rate, leading to 95% conversion after 3 h. The remarkable role of the Nb species is due to its interaction with H2O2 towards peroxo/superoxo species. Modification of both zeolites with zirconium does not increase their activity because of the strong interaction of zirconium species with sulfur compounds. This journal is
- Wojtaszek-Gurdak, Anna,Ziolek, Maria
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p. 22326 - 22333
(2015/03/14)
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- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
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The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
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The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Synthesis of biomass-derived methylcyclopentane as a gasoline additive via aldol condensation/hydrodeoxygenation of 2,5-hexanedione
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A novel approach to produce biomass-derived gasoline is the hydrolysis of 2,5-dimethylfuran (DMF) to produce 2,5-hexanedione followed by base-catalyzed intramolecular aldol condensation of this product to form 3-methylcyclopent-2-enone (MCP). By proper choice of catalysts and conditions, MCP yields of 98% can be achieved. We further show that hydrogenation of MCP over Pt/NbOPO4 gives methylcyclopentane with virtually quantitative yields. Methylcyclopentane is an attractive gasoline substitute for ethanol, since its octane number is similar to ethanol and its gravimetric energy density is 58% higher. This journal is
- Sacia, Eric R.,Deaner, Matthew H.,Louie, Ying Lin,Bell, Alexis T.
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supporting information
p. 2393 - 2397
(2015/04/27)
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- Selective Hydrogenation of Phenol to Cyclohexanone over Pd-HAP Catalyst in Aqueous Media
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The production of pure cyclohexanone under mild conditions over catalysts with high reactivity, selectivity, compatibility, stability, and low cost is still a great challenge. Here we report a hydroxyapatite-bound palladium catalyst (Pd-HAP) to demonstrate its excellent performance on phenol hydrogenation to cyclohexanone. Based on catalyst characterization, the Pd nanoclusters (≈0.9 nm) are highly dispersed and bound to phosphate in HAP. Only basic active sites on HAP surface are detected. At 25°C and ambient H2 pressure in water, phenol can be 100% converted into cyclohexanone with 100% selectivity. This system shows a universal applicability to temperature, pH, solvent, low H2 purity, and pressure. The catalyst reveals high stability to be recycled without deactivation or morphology change; and Pd nano-clusters barely aggregate even at 400°C. During the reaction, HAP adsorbs phenol, and Pd nanoclusters activate and spillover H2. The mechanism is also investigated, proposed, and verified.
- Xu, Guangyue,Guo, Jianhua,Zhang, Ying,Fu, Yao,Chen, Jinzhu,Ma, Longlong,Guo, Qingxiang
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p. 2485 - 2492
(2015/08/24)
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- Surface and catalytic properties of Ce-, Zr-, Au-, Cu-modified SBA-15
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Au- and CeO2-containing catalysts, supported on SBA-15 mesoporous molecular sieves and loaded with additives such as Cu and Zr species, were obtained and characterised. Cerium oxides are preferentially located in the bulk of SBA-15, whereas Zr species on its surface. Gold and copper loaded on supports strongly interact resulting in the electron transfer from Cu + to metallic gold, thus enhancing redox properties. Moreover, cerium species interact with gold, increasing redox properties of the system. The presence of copper increases the gold dispersion. Ce- and Zr-containing supports contain Lewis acid sites (LAS). The number of LAS is increased by the modification with copper species, whereas gold loading diminishes the LAS content. The presence of Zr species is responsible for Bronsted acidity and directs the oxidation of methanol to dimethyl ether. Copper enhances the selectivity to methyl formate. Gold and cerium are responsible for total oxidation of methanol, which is enhanced by modification with copper. The most attractive catalyst for low temperature total oxidation of methanol is bimetallic AuCu/CeSBA-15.
- Kaminski, Piotr,Ziolek, Maria
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p. 249 - 262
(2014/04/03)
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- METHODS FOR PRODUCING FUELS, GASOLINE ADDITIVES, AND LUBRICANTS
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The present disclosure generally relates to the production of fuels, gasoline additives, and/or lubricants, and precursors thereof. The compounds used to produce the fuels, gasoline additives, and/or lubricants, and precursors thereof may be derived from biomass. The fuels, gasoline additives, and/or lubricants, and precursors thereof may be produced by a combination of intermolecular and/or intramolecular aldol condensation reactions, Guerbet reactions, hydrogenation reactions, and/or oligomerization reactions.
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Paragraph 0157; 0158
(2015/01/06)
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- Relationship between basicity, reducibility and partial oxidation properties of chromium containing MCM-41
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MCM-41 mesoporous solids were modified with chromium species using Cr(NO3)3 and CrO3 as precursors. The impact of metal amount and metal sources on the structural and textural parameters of the materials obtained was investigated. Their surface properties were analyzed using XRD, UV-Vis, H2-TPR (the state of Cr species) as well as test reactions (2-propanol decomposition and cyclization and dehydration of 2,5-hexsanedione). The catalytic activity of Cr/MCM-41 materials was tested in methanol partial oxidation. The relationships of reducibility, kind of chromium species, basicity of material surface and the catalysts performance in partial oxidation of methanol were examined and discussed. The impact of basicity on methanol oxidation was clearly documented. Di- and polychromate species were found to be responsible for high yields of formaldehyde.
- Trejda, MacIej,Brys, Malgorzata,Ziolek, Maria
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p. 62940 - 62946
(2015/02/19)
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- The sila-Pummerer reaction of γ-silyl substituted cycloalkanoyl sulfoxides: The first examples and a new approach to 3-substituted cycloalk-2-enones
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The thermal decomposition of 3-(α-trimethylsilyl)alkyl substituted 2-(phenylsulfinyl)cycloalkanones occurs via the γ-sila-Pummerer reaction, affording 3-substituted cycloalk-2-enones and unstable trimethylsilyl benzenesulfenate as an elimination by-product. The starting γ-silyl substituted cycloalkanoyl sulfoxides were obtained through the conjugate addition reaction of nucleophilic reagents to 2-(phenylsulfinyl)cycloalk-2- enones. The tandem conjugate addition/γ-sila-Pummerer reaction investigated here provides a new route to 3-substituted cycloalk-2-enones.
- Mikina, Maciej,Miko?ajczyk, Marian
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p. 3954 - 3956
(2014/07/08)
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- Microwave-assisted oxidation of alcohols by hydrogen peroxide catalysed by tetrabutylammonium decatungstate
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This work deals with catalytic activity of tetrabutylammonium decatungstate(VI) in the oxidation of selected alcohols with hydrogen peroxide as an oxidant using 1,2-dichloroethane/water or acetonitrile/water as a solvent system. Different forms of heating were compared. The highest conversions of substrates were achieved in the two phase system acetonitrile/water using microwave irradiation combined with elevated pressure. Finally, optimum parameters for these reactions in a microwave pressurised reactor were established and discussed.
- Galica, Mateusz,Kasprzyk, Wiktor,Bednarz, Szczepan,Bogdal, Dariusz
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p. 1240 - 1244
(2013/07/27)
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- Self-coupling of secondary alcohols by Ni/CeO2 catalyst
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Supported nickel catalysts are studied for the liquid phase CC self-coupling of aliphatic secondary alcohols under additive free conditions in N2 atmosphere. Among various Ni catalysts, 1 or 3 wt% Ni/CeO 2 catalysts pre-reduced in H2 shows highest yield (94%) of a dimer product (a higher ketone) for the self-coupling of 1-octanol at 130 C, and the catalyst is reused. The catalysts are also effective for self-coupling of various secondary alcohols, providing the first heterogeneous catalytic system for the self-coupling of secondary alcohols under mild conditions. Effects of support material and oxidation state of Ni on the activity are studied and it is found that both CeO2 and metallic Ni are indispensable for the reaction. A possible reaction mechanism is proposed, in which ketones, formed by dehydrogenation of alcohol, undergone Aldol condensation to give α,β-unsaturated ketone which is finally hydrogenated by in situ formed NiH species.
- Shimura, Katsuya,Kon, Kenichi,Hakim Siddiki,Shimizu, Ken-Ichi
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p. 137 - 142
(2013/07/26)
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- The first observation of γ-sila-pummerer rearrangement
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2-Sulfinyl-3-trimethylsilylmethylcycloalkanones unexpectedly undergo γ-sila-Pummerer rearrangement. The first examples of this new type of rearrangement are presented.
- Mikina, Maciej
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p. 454 - 458
(2013/07/26)
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- Catalytic properties of new ternary Nb-Sb-V oxide - A comparative study with mechanical mixture of single oxides and binary systems
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The study presents a comparative analysis of catalytic properties of new Nb2SbVO10 ternary oxide against those of a mechanical mixture of single oxides and a mixture of single with binary oxide, all of the same chemical composition. Moreover, the material without antimony (Nb 9VO25) was tested. Acid-base and redox properties were studied in the following test reactions: 2-propanol decomposition, acetonylacetone (AcOAc) cyclisation and methanol oxidation. The properties of ternary oxide and the mechanical mixture of single oxides are not significantly different. The main difference is in the generation of more active Lewis acid-base pairs in ternary oxide, which is demonstrated by the higher production of ether in the intermolecular dehydration of 2-propanol. Acidic/basic and redox properties of the oxide catalysts containing Nb, Sb, V, O (atomic ratio: 2:1:1:10) strongly depend on the presence of binary oxide, which significantly enhances the basicity of the catalysts. The highest basicity was found for pure binary oxide Nb9VO25 but this catalyst without Sb exhibits much lower activity in the transformation of both alcohols.
- Ziolek, Maria,Golinska-Mazwa, Hanna,Filipek, Elzbieta,Piz, Mateusz
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experimental part
p. 159 - 167
(2012/07/28)
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- Polymer-mediated reactions. A Nazarov-like cyclization
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The polymer PEDOT+ mediates a Nazarov-like cyclization of dienones, in an heterogeneous system and in hydrocarbon solvents. The polymer-mediated reactions show clear differences in product formation when compared to the same reaction with tosic acid, or when compared to reports in the literature. Comparable or improved yields are observed, as well as the ability to give a -Nazarov product in cases where treatment with acid fails to give cyclization, or leads to an undesirable rearrangement. In addition, the ability to recycle the polymer makes this a potentially useful protocol for an important organic chemical reaction. Georg Thieme Verlag Stuttgart · New York.
- Pavlik, Christopher,Morton, Martha D.,Invernale, Michael A.,Berghorn, Ian D.,Sotzing, Gregory A.,Smith, Michael B.
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supporting information; experimental part
p. 2195 - 2199
(2011/11/06)
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- New Nb and Ta-FAU zeolites - Direct synthesis, characterisation and surface properties
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Niobium and tantalum containing Y zeolites were prepared in a one-pot synthesis and via solid-state ion exchange. The first method led to the incorporation of Nb and Ta into the zeolite framework as documented by XRD, UV-vis, XPS and test reactions. The efficiency of the metal introduction was higher for tantalum than for niobium. The presence of Lewis acid sites was proved by pyridine adsorption and cracking of cumene, whereas basic hydroxyls on the surface were evaluated on the basis of 3-methyl-2-cyclopentenone formation in the cyclisation of acetonyl acetone.
- Trejda,Wojtaszek,Floch,Wojcieszak,Gaigneaux,Ziolek
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experimental part
p. 170 - 177
(2011/01/12)
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- Mesoporous sodalite: A novel, stable solid catalyst for base-catalyzed organic transformations
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Mesoporous sodalite with a mesoporous/microporous hierarchical structure was successfully synthesized using an organosilane surfactant. It showed about 10-fold high surface area and 4-fold large pore volume, as compared with sodalite with solely microporous structure. The basicity of MPSOD was higher than that of CsNaX or KAlMCM-41. The catalytic activities of this mesoporous zeolite were evaluated for various base catalyzed reactions involving bulky and small substrates, viz. Knoevenagel condensation, Claisen-Schmidt condensation in liquid phase, and acetonylacetone cyclization in vapor phase. The catalyst showed higher activity and longer lifetime than CsNaX and KAlMCM-41.
- Shanbhag, Ganapati V.,Choi, Minkee,Kim, Jeongnam,Ryoo, Ryong
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body text
p. 88 - 92
(2009/09/30)
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- Cobalt-Catalyzed Oxidations in Volumetrically Expanded Liquids by Compressed Gases
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Oxidations of hydrocarbons, cycloalkanes and alkenes, arylalkanes, and a variety of other organic substrates are accomplished by cobalt-N-hydroxysuccinimide co-catalyzed reactions with dioxygen under unusually mild, near ambient conditions of temperature and pressure. The improved safety of the oxidation method and the high yields of product obtained make use of a unique combination of cobalt (II) complexes with N-hydroxysuccinimide. These autoxidation reactions do not have prolonged initiation times. Many of these reactions can be safely performed under normal chemical laboratory conditions and do not require specialized equipment or reagents.
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Page/Page column 8
(2008/12/06)
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- Mild manganese(III) acetate catalyzed allylic oxidation: Application to simple and complex alkenes
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Manganese(III) acetate catalyzed allylic oxidation of alkenes to the corresponding enones was investigated, showing excellent regioselectivity and chemoselectivity (functional group compatibility). Δ5-Steroids were transformed into bioactive Δ5-en-7-ones under a nitrogen atmosphere, whereas simple alkenes were converted into the corresponding enones under an oxygen atmosphere in good yields.
- Shing, Tony K. M.,Yeung, Ying-Yeung,Su, Pak L.
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p. 3149 - 3151
(2007/10/03)
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- 2-CYCLOPENTEN-1-ONE OXIME DERIVATIVES INHIBITING PRODUCTION OF TNF-ALPHA
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2-cyclopenten-1-one oxime derivatives represented by Formula (I), or pharmaceutically acceptable salts thereof inhibit the production of TNF-α or PDE4, and therefore show therapeutic effect in inflammatory or immunological disorders mediated through TNF-α or PDE4.
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Page/Page column 33-34
(2008/06/13)
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- One-pot β-substitution of enones with alkyl groups to β-alkyl enones
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Vinylic hydrogens at the β-position of enones were effectively substituted with alkyl groups in a one-pot procedure to afford β-alkyl enones in good to high isolated yields by conjugate addition of higher-order dialkyl cyanocuprates to enones, followed by a reaction with N-tert-butylbenzenesulfinimidoyl chloride at -78 °C. The Royal Society of Chemistry 2005.
- Matsuo, Jun-Ichi,Aizawa, Yayoi
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p. 2399 - 2401
(2007/10/03)
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- Selective dehydrogenation of alcohols and diols catalyzed by a dihydrido iridium PCP pincer complex
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The PCP pincer complex, IrH2{C6H3-2,6-(CH2P-t-Bu 2)2} (1) catalyzes the transfer dehydrogenation of primary and secondary alcohols. Dehydrogenation occurs across the C - O bond rather than the C - C bonds and the corresponding aldehydes or ketones are obtained as the sole products arising from the dehydrogenation reactions. Methanol is an exception to this pattern of reactivity and undergoes only stoichiometric dehydrogenation with 1 to give the carbonyl complex, Ir(CO){C6H3-2,6-(CH2P-t-Bu2) 2} (2). The products are obtained in nearly quantitative yields when the reactions are carried out in toluene solutions. Under the same conditions, 2,5-hexanediol is converted to the annulated product, 3-methyl-2-cyclopenten-1-one which has been isolated in 91% yield in a preparative scale reaction.
- Morales-Morales,Redon,Wang,Lee,Yung,Magnuson,Jensen
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p. 823 - 829
(2007/10/03)
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- An easy deoxygenation of conjugated epoxides
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An easy and high yielding transformation of epoxyketones and phenyl substituted epoxides to trans olefins in a convergent diastereoselective process is reported. The method was applied to the selective C-25 hydroxy- functionalisation of 3-keio-Δ4-cholestan-3-one, a key intermediate for the synthesis of C-25 hydroxy vitamin D3. (C) 2000 Elsevier Science Ltd.
- Righi, Giuliana,Bovicelli, Paolo,Sperandio, Anna
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p. 1733 - 1737
(2007/10/03)
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- Rates and Equilibria of the Michael-Type Addition of Benzenethiol to 2-Cyclopenten-1-ones
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The triethylamine-catalyzed addition reactions of benzenethiol to 2-cyclopenten-1-one and its 2-and 3-methyl derivatives have been found to be appreciably reversible in chloroform solution. Rates and equilibria have been carefully measured at 25°C in order to assess the negative influence on addition exerted by methyl groups substituted on the carbon-carbon double bond. 2-Methyl-2-cyclopenten-1-one has been found to react with benzenethiol under kinetic control to give the cis adduct as the sole detectable product in a highly stereoselective anti addition process. However, on prolonged reaction times the system slowly evolved toward a new state of equilibrium in which the more stable trans adduct, derived from a syn addition mode, was the predominant isomer.
- Van Castelli, Valeria Axel,Bernardi, Fernando,Cort, Antonella Dalla,Mandolini, Luigi,Rossi, Ivan,Schiaffino, Luca
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p. 8122 - 8126
(2007/10/03)
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- Environmentally benign procedures for the preparation and isolation of 3-methylcyclopent-2-en-1-one
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A moderately yielding (50±4%) method for obtaining 3-methylcyclopent-2-en-1-one from hexane-2,5-dione in ≥99.5% purity was developed, using 2.1% (w/v) of aqueous KOH at reflux. However, the yield was increased to 80±5% by using considerably lower concentrations of base (0.1%) and higher temperature (200°C) with a conventionally heated autoclave or a microwave batch reactor. The preparation was scaled up with a larger autoclave and also with a continuous flow microwave reactor. The dione impurity was removed from the enone by preferential adsorption on an anion-exchange resin in the bisulfite form. The product was recovered from the aqueous phase with a hydrophobic resin. This environmentally benign, non-extractive isolation method has potential for broad applicability in cleaner production.
- Bagnell, Laurence,Bliese, Marianne,Cablewski, Teresa,Strauss, Christopher R.,Tsanaktsidis, John
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p. 921 - 925
(2007/10/03)
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- Aldol Reaction and Robinson-Type Annelation Catalyzed by Lanthanoid Triisopropoxides
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Lanthanoid triisopropoxides are active catalysts for aldol reactions.Aldehydes give the corresponding β-hydroxyaldehydes at low temperatures in good yields, whereas ketones are less reactive, but form condensation products at high temperatures.Exceptionally, γ- or δ-diketones easily undergo condensation to give five- and six-membered unsaturated ketones in high yields.The lanthanoid propoxides, catalyzing the Michael addition of ketones to α,β-unsaturated ketones, which give δ-diketones, are also good catalysts for the Robinson-type annelation.In these reactions, the catalytic activity of the lanthanum propoxide is higher than those of the heavy lanthanoid propoxides, and is almost comparable to that of sodium isopropoxide.Since aluminum triisopropoxide shows poor activity, the lanthanoid propoxides are considerably basic for trivalent metal alkoxides.
- Okano, Tamon,Satou, Yoshikazu,Tamura, Motoshi,Kiji, Jitsuo
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p. 1879 - 1886
(2007/10/03)
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- Intramolecular aldol condensations: Rate and equilibrium constants
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Rate and equilibrium constants have been determined for both the aldol addition and the elimination steps in the intramolecular condensation reactions of 2,5-hexanedione, 2,6-heptanedione, 1-phenyl-1,5-hexanedione, and 5-oxohexanal. The overall thermodynamics are similar for cyclization of 2,5-hexanedione and 2,6-heptanedione; conversion of 2,5-hexanedione to the corresponding enone is actually more favorable, but the cyclization of 2,5-hexanedione is 2400 times slower than that of 2,6-heptanedione. As expected on the basis of intermolecular analogs, the addition step is less favorable and slower for 1-phenyl-1,5-hexanedione, and the addition step for 5-oxohexanal is more favorable though similar in rate to that for heptanedione. Detailed analysis of the kinetics and equilibrium for all of these compounds, as well as 2-(2-oxopropyl)benzaldehyde, in terms of Marcus theory, leads to the same intrinsic barriers for the intramolecular reactions as were seen previously for the intermolecular reactions. This means that rate constants for intramolecular aldol reactions should be predictable from the energetics of the reactions and that the effective molarity can be calculated. Methods for estimating thermodynamic quantities for reactants and products of these reactions have been examined.
- Guthrie,Guo
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p. 11472 - 11487
(2007/10/03)
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- Process for preparing cyclopentenones
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A process for preparing a cyclopentenone by forming a two-phase mixture of a 1,4-diketone, a water immiscible organic solvent, and an aqueous base solution, and heating the mixture so as to convert the 1,4-diketone to a cyclopentenone which collects in the organic solvent phase.
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- Phosphane Alkylenes, 53. - Synthesis of α,β-Unsaturated Cycloalkanones from Bis - A Method for the Transformation of Acid Anhydrides into Carbocyclic and Heterocyclic Compounds
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Alkaline hydrolysis of bis 3 leads to 2-cycloalken-1-ones 6.Intramolecular Wittig reaction of an intermediately formed monoacyl ylide 4 and intramolecular aldol condensation of a diketone 5, resulting from hydrolysis of both ylide functions, are discussed as possible reaction mechanisms.The oxidation of 3 with H2O2 * Ph3PO yields 7- and 8-membered 2-cycloalkene-1,4-diones 12, presumely via mono ylides 11 carrying an aldehyde group in the ω-position.The reactions of 3 with aldehydes (molar ratio 1:1) lead to the formation of mono Wittig compounds 15 which can cyclize affording 5- and 6-membered 3-alkenyl-2-cycloalken-1-ones 16.Since the ylides 3 are easily available from acid anhydrides the reaction sequences represent versatile approaches for the transformation of acid anhydrides into 2-cycloalken-1-ones. Key Words: Phosphonium ylides / Wittig reactions, intramolecular / Aldol condensations, intramolecular / 2-Cycloalken-1-ones / 2-Cycloalken-1,4-diones
- Bestmann, Hans Juergen,Pichl, Rainer,Zimmermann, Reiner
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p. 725 - 732
(2007/10/02)
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- Cyclocarbonylation of acyclic 1,3-dienes via their tricarbonyl iron complexes: Cyclopenten-2-ones and dicarbonyl cyclopentadienyl iron halides
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Tricarbonyl iron complexes of acyclic 1,3-dienes can be converted to conjugated cyclopentenones by decomplexation with aluminium halides. Most complexes of simple dienes need drastic conditions for the cyclocarbonylation to occur (100 Atm CO, 100°C), with the exception of 1,1,3-trialkylbutadiene complexes which are nearly quantitatively converted into cyclopentenones at room temperature, even in the absence of a CO atmosphere. Under the same mild conditions, the other complexes lead in modest yields to cyclopentadienyl dicarbonyl iron halides by a cyclocarbonylation reaction followed by an aluminium halide promoted deoxygenation.
- Franck-Neumann,Michelotti,Simler,Vernier
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p. 7361 - 7364
(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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