- Synthetic ferripyrophyllite: Preparation, characterization and catalytic application
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Sheet silicates, also known as phyllosilicates, contain parallel sheets of tetrahedral silicate built up by [Si2O5]2- entities connected through intermediate metal-oxygen octahedral layers. The well-known minerals talc and pyrophyllite are belonging to this group based on magnesium and aluminium, respectively. Surprisingly, the ferric analogue rarely occurs in nature and is found in mixtures and conglomerates with other materials only. While partial incorporation of iron into pyrophyllites has been achieved, no synthetic protocol for purely iron-based pyrophyllite has been published yet. Here we report about the first artificial synthesis of ferripyrophyllite under exceptional mild conditions. A similar ultrathin two-dimensional (2D) nanosheet morphology is obtained as in talc or pyrophyllite but with iron(iii) as a central metal. The high surface material exhibits a remarkably high thermostability. It shows some catalytic activity in ammonia synthesis and can serve as catalyst support material for noble metal nanoparticles.
- Qiao, Yunxiang,Theyssen, Nils,Spliethoff, Bernd,Folke, Jan,Weidenthaler, Claudia,Schmidt, Wolfgang,Prieto, Gonzalo,Ochoa-Hernández, Cristina,Bill, Eckhard,Ye, Shengfa,Ruland, Holger,Schüth, Ferdi,Leitner, Walter
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p. 850 - 857
(2021/02/03)
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- Zeolite-Encapsulated Pt Nanoparticles for Tandem Catalysis
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Encapsulation of metal nanoparticles in a zeolite matrix is a promising route to integrate multiple sequential reactions into a one-pot and one-step tandem catalytic reaction. We report a cationic polymer-assisted synthetic strategy to encapsulate Pt nanoparticles (NPs) into MFI zeolites. Degrees of encapsulation of Pt NPs in the synthesized catalysts exceeding 90% were demonstrated via kinetic studies of model reactions involving substrates with different molecular dimensions. HZSM-5 zeolite-encapsulated Pt NPs are able to selectively mediate the tandem aldol condensation and hydrogenation of furfural and acetone to form hydrogenated C8 products with a combined yield of 87%. In contrast, hydrogenation and decarbonylation of furfural dominate on Pt NPs supported on HZSM-5 at otherwise identical conditions. The high selectivity toward the tandem reaction on the encapsulated catalyst is attributed to the distribution of metal and acid sites, which limits the access of furfural to Pt sites and promotes the acid-catalyzed aldol condensation. This is the first demonstration that the product distribution in a tandem reaction is manipulated by tailoring the architecture of catalytic materials via encapsulation.
- Cho, Hong Je,Kim, Doyoung,Li, Jing,Su, Dong,Xu, Bingjun
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supporting information
p. 13514 - 13520
(2018/10/20)
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- A Heterogeneous Metal-Free Catalyst for Hydrogenation: Lewis Acid–Base Pairs Integrated into a Carbon Lattice
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Designing heterogeneous metal-free catalysts for hydrogenation is a long-standing challenge in catalysis. Nanodiamond-based carbon materials were prepared that are surface-doped with electron-rich nitrogen and electron-deficient boron. The two heteroatoms are directly bonded to each other to form unquenched Lewis pairs with infinite π-electron donation from the surrounding graphitic structure. Remarkably, these Lewis pairs can split H2 to form H+/H? pairs, which subsequently serve as the active species for hydrogenation of different substrates. This unprecedented finding sheds light on the uptake of H2 across carbon-based materials and suggests that dual Lewis acidity–basicity on the carbon surface may be used to heterogeneously activate a variety of small molecules.
- Ding, Yuxiao,Huang, Xing,Yi, Xianfeng,Qiao, Yunxiang,Sun, Xiaoyan,Zheng, Anmin,Su, Dang Sheng
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supporting information
p. 13800 - 13804
(2018/10/20)
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- Solvent effects in hydrodeoxygenation of furfural-acetone aldol condensation products over Pt/TiO2 catalyst
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The solvent effects on hydrodeoxygenation (HDO) of 4-(2-furyl)-3-buten-2-one (F-Ac) over Pt/TiO2 catalyst were investigated at T = 200 °C and P(H2) = 50 bar. The initial reactant is the main product of aldol condensation between furfural and acetone, which constitutes a promising route for the production of bio-based chemicals and fuels. A sequence of experiments was performed using a selection of polar solvents with different chemical natures: protic (methanol, ethanol, 1-propanol, 2-propanol, 1-pentanol) and aprotic (acetone, tetrahydrofuran (THF), n,n-dimethylformamide (DMF)). In case of protic solvents, a good correlation was found between the polarity parameters and conversion. Consequently, the highest hydrogenation rate was observed when 2-propanol was used as a solvent. In contrast, the hydrogenation activity in presence of aprotic solvents was related rather to solvent-catalyst interactions. Thus, the initial hydrogenation rate declined in order Acetone > THF > DMF, i.e. in accordance with the increase in the nucleophilic donor number and solvent desorption energy. Regarding the product distribution, a complex mixture of intermediates was obtained, owing to the successive hydrogenation (aliphatic C[dbnd]C, furanic C[dbnd]C and ketonic C[dbnd]O bonds), ring opening (via C[sbnd]O hydrogenolysis) and deoxygenation reactions. Based on the proposed reaction scheme for the conversion of F-Ac into octane, the influence of the studied solvents over the cascade catalytic conversion is discussed. A significant formation of cyclic saturated compounds such as 2-propyl-tetrahydropyran and 2-methyl-1,6-dioxaspiro[4,4]nonane took place via undesirable side reactions of cyclization and isomerization. The best catalytic performance was found when using acetone and 2-propanol as solvents, achieving significant yields of 4-(2-tetrahydrofuryl)-butan-2-ol (28.5–40.4%) and linear alcohols (6.3–10.4%). The better performance of these solvents may be associated with a lower activation energy barrier for key intermediate products, due to their moderate interaction with the reactant and the catalyst. In case of methanol and DMF, undesired reactions between the reactant and the solvent took place, leading to a lower selectivity towards the targeted hydrodeoxygenated products.
- Ramos, Rubén,Ti?ler, Zdeněk,Kikhtyanin, Oleg,Kubi?ka, David
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p. 174 - 183
(2016/12/06)
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- kind of eggplant Nepal furan perfume and its synthetic method (by machine translation)
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The invention relates to kind of eggplant Nepal furan perfume and its synthetic method. The perfume has eggplant Nepal furan precursor structure similar to, the main functional group include [...] and acetylprotoaescigenin, has a similar fragrance eggplant Nepal furan. Only two-step reaction can be used for synthesizing the states kind of eggplant Nepal furan compound. Synthetic route to furfuran compound to be de-protonated reagent after dehydrogenation, the reaction of an olefin with a leaving group to produce intermediate; then Wacker oxidation reaction of such eggplant Nepal furyl compound is obtained. (by machine translation)
- -
-
Paragraph 0015
(2016/10/31)
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- Enhancing the Catalytic Properties of Ruthenium Nanoparticle-SILP Catalysts by Dilution with Iron
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The partial replacement of ruthenium by iron ("dilution") provided enhanced catalytic activities and selectivities for bimetallic iron-ruthenium nanoparticles immobilized on a supported ionic liquid phase (FeRuNPs@SILP). An organometallic synthetic approach to the preparation of FeRuNPs@SILP allowed for a controlled and flexible incorporation of Fe into bimetallic FeRu NPs. The hydrogenation of substituted aromatic substrates using bimetallic FeRuNPs@SILP showed high catalytic activities and selectivities for the reduction of a variety of unsaturated moieties without saturation of the aromatic ring. The formation of a bimetallic phase not only leads to an enhanced differentiation of the hydrogenation selectivity, but even reversed the order of functional group hydrogenation in certain cases. In particular, bimetallic FeRuNPs@SILP (Fe:Ru = 25:75) were found to exhibit accelerated reaction rates for C=O hydrogenation within furan-based substrates which were >4 times faster than monometallic RuNPs@SILP. Thus, the controlled incorporation of the non-noble metal into the bimetallic phase provided novel catalytic properties that could not be obtained using either of the monometallic catalysts.
- Luska, Kylie L.,Bordet, Alexis,Tricard, Simon,Sinev, Ilya,Grünert, Wolfgang,Chaudret, Bruno,Leitner, Walter
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p. 3719 - 3726
(2016/07/06)
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- Towards understanding the hydrodeoxygenation pathways of furfural-acetone aldol condensation products over supported Pt catalysts
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Aiming at the valorisation of furfural-derived compounds, the hydrodeoxygenation of furfural-acetone condensation products has been studied using supported platinum catalysts. The influence of the catalytic properties of different supports, such as SiO2, Al2O3, TiO2, hydrotalcite (HTC), Beta zeolite, Al-SBA-15 and WO3-ZrO2, was evaluated in a batch reactor for 480 min at 200 °C and 50 bar of H2. The used feed consisted of a mixture of furfural-acetone adducts (C8-C19), obtained in previous experiments using a continuous flow reactor and hydrotalcite as a catalyst. Except for Pt/SiO2, all catalysts showed high conversion of the reactants, especially due to the hydrogenation of all the aliphatic CC bonds. However, the extent of further hydrogenation (furan CC and ketone CO bonds) was limited, particularly when HTC and Al2O3 were used as supports. The higher accessibility of Pt/TiO2 and the smaller Pt particle size shown by Pt/Al-SBA-15, Pt/WO3-ZrO2 and Pt/Beta in comparison with the other catalysts led to an improvement in the hydrogenation of furanic and ketonic groups, likely due to lower adsorption constraints. The higher acid character of the latter group of catalysts promotes dehydration and ring opening steps, thus enhancing the selectivity towards linear alcohols. Likewise, a significant increase in the extent of aldol condensation reactions was also observed with these catalysts, yielding longer carbon chain compounds. Based on this study, a reaction scheme for the transformation of 4-(2-furyl)-3-buten-2-one (C8) into octane has been proposed in order to establish a valuable correlation between the main conversion pathways and the catalytic properties of the employed heterogeneous catalyst, thus contributing to further development of efficient deoxygenation catalysts.
- Ramos,Ti?ler,Kikhtyanin,Kubi?ka
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p. 1829 - 1841
(2016/04/05)
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- Functional group dependence of the acid catalyzed ring opening of biomass derived furan rings: An experimental and theoretical study
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We describe studies of Bronsted acid catalyzed ring opening of substituted furans contained within biomass derived C8- and C9- molecules. Ring opening occurs homogeneously under relatively mild conditions of 80°C using catalytic hydrochloric acid. In the case of 4-(5-methyl-2-furyl) -2-butanone (1a), the reaction proceeds to a single product in up to 92% yield after 24 hours. For 4-(2-furanyl)-2-butanone (1b) and 4-(5-hydroxymethyl)-2- furanyl-2-butanone (1c), however, multiple products are observed, illustrating the significant influence of furan ring substituents on the reactivity of this class of compounds. The generality of these reaction pathways was tested using several other similar substrates. Kinetics experiments indicate that ring opening of 1a occurs via specific acid catalysis, and computations elucidate the effect of initial protonation on the reaction pathway. Calculated pK a values were calibrated against experimentally measured values and are consistent with observed reactivities. Inclusion of explicit, hydrogen-bonded water molecules in addition to the SMD solvent model is necessary when studying protonation of alcohol and ketone groups. The Royal Society of Chemistry 2013.
- Waidmann, Christopher R.,Pierpont, Aaron W.,Batista, Enrique R.,Gordon, John C.,Martin, Richard L.,Pete Silks,West, Ryan M.,Wu, Ruilian
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p. 106 - 115
(2013/03/29)
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- Cooperative effects in catalytic hydrogenation regulated by both the cation and anion of an ionic liquid
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The use of transition-metal nanoparticles/ionic liquid (IL) as a thermoregulated and recyclable catalytic system for hydrogenation has been investigated under mild conditions. The functionalized ionic liquid was composed of poly(ethylene glycol)-functionalized alkylimidazolium as the cation and tris(meta-sulfonatophenyl)phosphine ([P(C6H4-m-SO 3)3]3-) as the anion. Ethyl acetate was chosen as the thermomorphic solvent to avoid the use of toxic organic solvents. Due to a cooperative effect regulated by both the cation and anion of the ionic liquid, the nanocatalysts displayed distinguished temperature-dependent phase behavior and excellent catalytic activity and selectivity, coupled with high stability. In the hydrogenation of α,β-unsaturated aldehydes, the ionic-liquid-stabilized palladium and rhodium nanoparticles exhibited higher selectivity for the hydrogenation of the C=C bonds than commercially available catalysts (Pd/C and Rh/C). We believe that the anion of the ionic liquid, [P(C6H4-m-SO3)3]3-, plays a role in changing the surrounding electronic characteristics of the nanoparticles through its coordination capacity, whereas the poly(ethylene glycol)-functionalized alkylimidazolium cation is responsible for the thermomorphic properties of the nanocatalyst in ethyl acetate. The present catalytic systems can be employed for the hydrogenation of a wide range of substrates bearing different functional groups. The catalysts could be easily separated from the products by thermoregulated phase separation and efficiently recycled ten times without significant changes in their catalytic activity. Copyright
- Zhu, Wenwen,Yu, Yinyin,Yang, Hanmin,Hua, Li,Qiao, Yunxiang,Zhao, Xiuge,Hou, Zhenshan
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p. 2059 - 2066
(2013/03/28)
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- Photooxidations of 2-(γ,ε-dihydroxyalkyl) furans in water: Synthesis of DE-bicycles of the pectenotoxins
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Photooxygenations of 2-(γ,ε-dihydroxyalkyl) furans in H 2O followed by in situ reduction and ketalization affords, in one synthetic operation, DE-bicyclic ketals of the pectenotoxins.
- Kouridaki, Antonia,Montagnon, Tamsyn,Tofi, Maria,Vassilikogiannakis, Georgios
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supporting information; experimental part
p. 2374 - 2377
(2012/07/01)
-
- Vinyl polymerization versus [1,3] O to C rearrangement in the ruthenium-catalyzed reactions of vinyl ethers with hydrosilanes
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Two reactions, vinyl polymerization and [1,3] O to C rearrangement of vinyl ethers, are investigated in the ruthenium-catalyzed reaction with hydrosilanes. The reaction pathways are dependent on the substituents of the vinyl ether, in particular, those of the alkoxy group. Primary-, secondary-, and tertiary-alkyl vinyl ethers, ROCHCH2, are polymerized with ease to give the corresponding polymer in good yields. When R is electron-donating benzyl groups, the reaction does not give the polyvinyl ether but results in [1,3] O to C rearrangement to give the corresponding aldehyde, RCH2CHO in moderate to good yields. The rearrangement selectively proceeds when vinyl ethers having α-substituents are used as the starting materials to give the corresponding ketones in high yields. With catalytic amounts of hydrosilanes, the rearrangement gives ketones or aldehydes selectively. In sharp contrast, use of excess amounts of hydrosilanes leads to the rearrangement followed by reduction of the formed carbonyl group to give the corresponding silyl ethers in good yields. Nature of catalytically active species is discussed. Crown Copyright
- Harada, Nari-Aki,Nishikata, Takashi,Nagashima, Hideo
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supporting information; experimental part
p. 3243 - 3252
(2012/06/01)
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- Selective hydrogenation of biomass derived substrates using ionic liquid-stabilized ruthenium nanoparticles
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Ionic liquid-stabilized ruthenium nanoparticles with an average size between 2-3 nm are very active catalysts for the hydrogenation of biomass derived substrates. Their catalytic performance complements that of classic homogeneous and heterogeneous ruthenium catalysts.
- Julis, Jennifer,Hoelscher, Markus,Leitner, Walter
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experimental part
p. 1634 - 1639
(2010/12/24)
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- Production of linear alkane via hydrogenative ring opening of a furfural-derived compound in supercritical carbon dioxide
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A simple method has been described to accomplish the formation of linear alkane with >99% selectivity in supercritical carbon dioxide under very mild conditions using Pd/Al-MCM-41 catalyst. The linear alakne was formed through the hydrogenation and dehydration/hydrogenation of 4-5-(5-(hydroxymethyl)furan-2- yl)but-3-en-2-one, which is an aldol condensation product of 5-hydroxymethyl furfural and acetone.
- Chatterjee, Maya,Matsushima, Keichiro,Ikushima, Yutaka,Sato, Masahiro,Yokoyama, Toshirou,Kawanami, Hajime,Suzuki, Toshishige
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experimental part
p. 779 - 782
(2010/09/06)
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- Chemoselective conjugate reduction of α,β-unsaturated ketones catalyzed by rhodium amido complexes in aqueous media
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Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C-O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C-O to C-C bonds in the transfer hydrogenation of activated α,β-unsaturated ketones. Now we have found that a variety of α,β-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.
- Li, Xuefeng,Li, Liangchun,Tang, Yuanfu,Zhong, Ling,Cun, Linfeng,Zhu, Jin,Liao, Jian,Deng, Jingen
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experimental part
p. 2981 - 2988
(2010/07/05)
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- A facile and chemoselective conjugate reduction using polymethylhydrosiloxane (PMHS) and catalytic B(C6F5) 3
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A highly chemoselective conjugate reduction of electron-deficient Michael acceptors, including Α, β-unsaturated ketones, carboxylic esters, nitriles and nitro compounds with PMHS in the presence of catalytic B(C 6F5)3 was investigated. When attempts were made to improve the yields by increasing the amount of catalyst, the result was a complex mixture of saturated and unsaturated compounds, with partial reduction of the ketone moiety to the methylene functionality. PMHS along with a catalytic amount of B(C6F5)3 was found to be a unique reagent system for the conjugate reduction of Michael acceptors.
- Chandrasekhar, Srivari,Chandrashekar, Gudise,Reddy, Marepally Srinivasa,Srihari, Pabbaraja
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p. 1650 - 1652
(2008/02/03)
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- Efficient role of Mg-ZnCl2 for selective reduction of α,β-unsaturated carbonyl compounds in aqueous medium
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A facile strategy for the convenient reduction of α,β- unsaturated carbonyl compounds and conjugated alkynes has been accomplished by Mg-ZnCl2 system in aqueous medium. Georg Thieme Verlag Stuttgart.
- Saikia, Anil,Barthakur, Madan Gopal,Boruah, Romesh Chandra
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p. 523 - 525
(2007/10/03)
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- Chemoselective Reduction of α,βUnsaturated Aldehydes, Ketones, Carboxylic Acids, and Esters with Nickel Boride in Methanol-Water
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A facile procedure for the conjugate reduction of α,β -unsaturated aldehydes, ketones, carboxylic acids, and esters is reported with nickel boride generated in situ from NiCl2·6H 2O/NaBH4 in methanol-water at ambient temperature.
- Khurana, Jitender Mohan,Sharma, Purnima
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p. 549 - 552
(2007/10/03)
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- Chemoselective reduction of α, β-unsaturated carbonyl compounds by sodium hydrogen telluride: Part I
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Sodium Hydrogen Telluride is used for the selective reduction of C=C bonds in various chalcones. The reduction proceeds smoothly in good yields.
- Geethamalika,Suguna Sundari,Shanmugam,Rajendran
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p. 674 - 676
(2007/10/03)
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- The HfCl4-mediated Diels-Alder reaction of furan
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High yields and high endo selectivity of the cycloadducts formed from the Diels-Alder reaction of furan or substituted furans occurs with an HfCl4 catalyst (see scheme). The use of the catalyst allows reactions to be performed at low temperature under kinetic control, as shown for the highly diastereoselective Diels-Alder reaction of a chiral acrylate.
- Hayashi, Yujiro,Nakamura, Masahiko,Nakao, Shigehiro,Inoue, Tae,Shoji, Mitsuru
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p. 4079 - 4082
(2007/10/03)
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- Indium metal as a reducing agent. Selective reduction of the carbon-carbon double bond in highly activated conjugated alkenes
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(Equation presented) Indium metal in aqueous ethanolic ammonium chloride reduces the C=C bond in highly activated conjugated alkenes such as α,α-dicyano olefins, β-arylenones, and enone esters.
- Ranu, Brindaban C.,Dutta, Jyotirmoy,Guchhait, Sankar K.
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p. 2603 - 2605
(2007/10/03)
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- Dynamic kinetic resolution of allylic alcohols mediated by ruthenium- and lipase-based catalysts.
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An enzyme-metal combo reaction has been developed for the dynamic kinetic resolution of allylic alcohols in which racemic substrates are transformed by a lipase and a ruthenium complex in the presence of an acyl donor to allylic acetates of high optical purity in over 80% yield.
- Lee,Huh,Kim,Jung,Koh,Park
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p. 2377 - 2379
(2007/10/03)
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- Substituent Effects in the Intramolecular Diels-Alder Reaction of 6-Furylhexenoates
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The series of furyl enone esters, 4a-c, were synthesized from furan or furfural by straightforward routes. Their thermal intramolecular Diels-Alder reactions to give the tricyclic ketones 5a-c were studied in acetonitrile and toluene at two temperatures and the kinetics of the reactions determined. A comparison of these data with that obtained for the corresponding esters 2 to give the lactones 3 indicates that the rate enhancements seen for the esters (rate of dimethyl 310 times that of monomethyl) are much larger than those seen for the ketones (rate of dimethyl 6.8 times that of monomethyl). Thus, this is additional evidence for the earlier hypothesis that the presence of the oxygen atom in the tether is a factor responsible for the larger than normal rate enhancements.
- Jung, Michael E.,Kiankarimi, Mehrak
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p. 2968 - 2974
(2007/10/03)
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- Conjugate Michael additions with mixed diorganozincs
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Functionalised mixed alkyl(trimethylsilylmethyl)zinc reagents add efficiently to a wide variety of Michael acceptors in high yield and with exclusive 1,4-regioselectivity, without the need for transition metal catalysis. The trimethylsilylmethyl group behaves as a non-transferable group, and in no cases was transfer of this group observed.
- Jones, Philip,Kishan Reddy,Knochel, Paul
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p. 1471 - 1490
(2007/10/03)
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- Clay-catalyzed solventless addition reactions of furan with α,β- unsaturated carbonyl compounds
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The reaction of furan with α,β-unsaturated carbonyl dienophiles catalyzed by K10 montmorillonite in the absence of organic solvents produces the corresponding Diels-Alder adducts and, in the case of methyl vinyl ketone, Michael-type products, under much milder conditions than the conventional protocols. The results are consistent with acid catalysis on the clay surface. Acrylates gave lower yields and/or decomposition products. The reaction can be extended to alkynic substrates such as DMAD to afford cycloadducts in good yields.
- Avalos, Martin,Babiano, Reyes,Bravo, Jose L.,Cintas, Pedro,Jimenez, Jose L.,Palacios, Juan C.
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p. 9301 - 9304
(2007/10/03)
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- Conjugate Michael-additions with mixed diorganozincs
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Mixed diorganozincs (RZnCH2SiMe3; R = alkyl, aryl) undergo selective transfer of the R group in a 1,4-fashion to various Michael-acceptors.
- Jones, Philip,Knochel, Paul
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p. 3117 - 3118
(2007/10/03)
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- Selective Hydrogenation of α,β-Unsaturated Aldehydes and Ketones of the Furan Series in the Presence of Pd2+ Complexes
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α,β-Unsaturated aldehydes and ketones of the furan series are selectively reduced to the corresponding saturated furan derivatives over γ-Al2O3supported Pd2+ complexes with azo compounds. The effects of some factors (temperature, solvent, various additions) on the reduction process are discussed.
- Shebaldova,Safronova,Kravtsova
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p. 109 - 112
(2007/10/03)
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- Aluminium trichloride hexahydrate-zinc-THF-A new system for the reduction of carbon-carbon double bonds
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Aluminium trichloride hexahydrate-Zn-THF system selectivity reduces α,β-unsatureted carbonyl and enedicarbonyl compounds to the corresponding dihydro compounds in good yields.
- Konwar, Dilip,Dutta, Dilip Kumar,Sandhu, Jagir Singh
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p. 725 - 727
(2007/10/03)
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- Reductive Biotransformation of Carbonyl Compounds --- Application of Fungus Geotrichum sp. G38 in Organic Synthesis
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The microbial transformation of 2- and 3-oxo esters and diketones with Geotrichum sp.G38 and its application to the syntheses of the key intermediates of several bioactive compounds such as (R)-denopamine 8, (R)-fluoxetine 11 and (2S,3R)-sitophilate 14 were described.
- Jian-Xin, Gu,Zu-Yi, Li,Guo-Qiang, Lin
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p. 5805 - 5816
(2007/10/02)
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- 4,7-Dioxooctanoic Acid from the Acid Catalysed Reaction of (E)-4-(2-furyl)but-3-enone. Electrochemical Hydrogenation of some Furan Derivatives
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A two phase acidic reaction medium has been developed for the conversion of (E)-4-(2-furyl)but-3-enone into 4,7-dioxooctanoic acid in consistent yields of 50percent with concomitant formation of 15percent polymer.The corresponding ring opening of 1-(2-furyl)-5-methylhex-1-en-3-one proceeds in homogeneous acid solution in very high yield without polymer formation.The two furylalkenones can be reduced electrochemically to the corresponding furylalkylketones in good yields at a lead cathode in the presence of sodium hydrogen carbonate.
- Abeysekera, Ajita M.,Amaratunge, Shiyamalie,Grimshaw, James,Jayeweera, Nihal,Senanayake, Gamini
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p. 2021 - 2023
(2007/10/02)
-
- Selective Reduction of α,β-Unsaturated Carbonyl Compounds with Carbon Monoxide and Water Assisted by Seleniium
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Carbon-carbon double bond of α,β-unsaturated carbonyl compounds can be reduced selectively with hydrogen selenide, generated in situ by the reaction of elemental selenium with carbon monoxide and water in the presence of strongly basic tertiary amine.
- Nishiyama, Yutaka,Makino, Yasuhiko,Hamanaka, Sawako,Ogawa, Akiya,Sonoda, Noboru
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p. 1682 - 1684
(2007/10/02)
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- DRAMATIC ACCELERATION OF THE DIELS-ALDER REACTION BY ADSORPTION ON CHROMATOGRAPHY ADSORBENTS
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The development of a new method for effecting cycloadditions on the surface of chromatographic adsorbents in the absence of solvents that leads to a moderation of the reaction conditions and an increase in selectivity is described.
- Veselovsky, V. V.,Gybin, A. S.,Lozanova, A. V.,Moiseenkov, A. M.,Smit, W. A.,Caple, R.
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p. 175 - 178
(2007/10/02)
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- CONJUGATE ADDITION OF FURANS TO ENONES OR THEIR SYNTHETIC EQUIVALENTS
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Conjugate addition of furans 5 to enones 3 in the presence of an alcohol and boron trifluoride etherate is described.A same reaction product is obtained with hemiacetal vinylogs 1, synthetic equivalents of enones 3.Acidic treatment of adducts 6 and 7 leads to tri- and tetraketones 15 and 16.
- Poirier, Jean-Marie,Dujardin, Gilles
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p. 399 - 407
(2007/10/02)
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- Influence de la pression sur les reactions de substitution electrophile du furanne et de methyl-2 furanne
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We previously investigated the (4+2) cycloaddition reactions of 2-methylfuran, which are known to be very difficult, even impossible, under the usual conditions for Diels-Alder reactions.We found that the adducts are generated only at low temperatures (20-40 deg C) and high pressures (ca. 10 kbar)(Bull.Soc.Chim., 1978, p.461).However, by increasing the temperature, we have observed the alternative reaction consisting in the α-substitution of furan when furan compounds are allowed to react with α,β-unsaturated carbonyl compounds at temperatures above 100 deg C.We found that this reaction, which proceeds slowly (or not at all) at atmospheric pressure, is noticeably faster at high pressures.Having in mind a simple method for facile synthesis of mono- and disubstituted furans, we thought that pressure could be an interesting parameter in producing such compounds in high yield.Additionally, since the reaction was found some time ago to be very sensitive to acidic media (electrophilic substitution of the Friedel-Crafts type), we imagined that a possible pressure induced creation of charges in the transition state would give rise to an electrostriction contribution to the reaction rate.We first investigated the thermal synthesis without catalyst and found that only unsaturated carbonyl compounds show some reactivity, while unsaturated nitriles or esters do not react.However, the substitution reaction is considerably perturbed by the polymerisation reaction, which is also positively influenced by pressure and thus reduces drastically the yield of substituted products, except in some rare cases.The use of a suitable catalyst (AcOH-H2O) combined with pressure (3 000 bar) allows satisfactory yields of substituted furans with little formation of polymer.The pressure kinetics of two selected reactions reveals a strong pressure acceleration with activation volumes in the range (-45 to -50 cm3/mol) independent of the solvent.We suggest that starting from a neutral initial state, during the activation process there is a development of electrostriction with the possible appearance of strongly polarized species, the polarization being enhanced by pressure.However, in this case we would normally anticipate a solvent dependence of the activation volume ΔV(excit.); in fact this effect is not observed.Nevertheless, the hypothesis of electrostriction is quite plausible by the fact that, when the reaction is carried out in the presence of the catalyst (AcOH-H2O), the value ΔV(excit.) is reduced to half the former value (-24.5 cm3/mol), because the initial state is no longer neutral and charges are present along the activation process.
- Jenner, Gerard,Rimmelin, Jean,Antoni, Francois,Libs, Suzanne,Schleiffer, Elisabeth
-
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- Cyclization substrates and related 11α-equatorially-substituted steroids
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Cyclisation substrates are disclosed of the formula: STR1 wherein: (a) R1 is H or alkyl of one to four carbon atoms; (b) R2 is H or alkyl of one to four carbon atoms, with the proviso that R1 is H when R2 is alkyl, and with the proviso that R2 is H when R1 is alkyl; (c) R3 is a suitable leaving group selected from the group consisting of hydroxy, alkoxy of one to four carbons, alkoxyalkoxy of two to four carbons, acyloxy of one to about seven carbon atoms, and trialkylsilyloxy of less than fifteen carbons; (d) R4 is methyl; and (e) R5(1) and R5(2) are each H, alkyl of one to eight carbons, or an optionally esterified or etherified hydroxy group selected from the group consisting of hydroxy, alkoxy of one to four carbons, alkoxyalkoxy of two to four carbons, trialkylsilyloxy of one to fifteen carbons, cycloalkoxy of four to eight carbons, carboxyacyloxy of one to seven carbons or heterocyclic ether of five to seven atoms and four to six carbons, with the proviso that at least one of R5(1) and R5(2) is hydrogen. A method is disclosed for the cyclisation of the compounds of formula I leading to compounds of the following formulae: STR2 having R4 and R5 (one of R5(1) and R5(2) that may or may not be hydrogen) as defined above, with R6 being alkyl of from one to about four carbon atoms.
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- SELECTIVE REDUCTION OF α,β-UNSATURATED CARBONYL COMPOUNDS BY SODIUM HYDROTELLURIDE
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Sodium hydrotelluride was found to serve as a new efficient agent for selective reduction of α,β-unsaturated carbonyl compounds under mild reaction conditions.
- Yamashita, Masakazu,Kato, Yukihiko,Suemitsu, Rikisaku
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p. 847 - 848
(2007/10/02)
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