- A Cationic Ru(II) Complex Intercalated into Zirconium Phosphate Layers Catalyzes Selective Hydrogenation via Heterolytic Hydrogen Activation
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Catalytic hydrogenations constitute economic and clean transformations to produce pharmaceutical and a multitude of fine chemicals in chemical industry. Herein, we report a cationic Ru(II) complex intercalated into zirconium phosphate (ZrP) layers that enables the efficient catalytic conversion of furfural and other biomass-derived carbonyl compounds into the corresponding alcohols through selective hydrogenation of C=O group. The ZrP layers acted not only as a support for the Ru-complex, but also as the new ligands to tune the Ru(II) center via forming Ru?O bond. The resulting catalysts exhibit excellent catalytic performance and can be easily recycled for six times without significant loss of activity and selectivity. The Ru(II) complex-intercalated catalysts have been characterized by XRD, SEM, HRTEM, HAADF-STEM, XPS, FT-IR, DR-UV/Vis, EXAFS and XANES. Especially, it is observed that the appropriate interlayer spacing between ZrP layers is favorable to stabilize the Ru(II) complex. Notably, on the basis of the further characterization and density functional theory (DFT) calculation, it is identified that the interaction of cationic Ru(II) complex and P?OH group within ZrP layers leads to the high catalytic performance in selective hydrogenation, and the newly formed Ru?O?P species plays a crucial role in the heterolytic hydrogen activation and selective hydrogenation of biomass-derived compounds containing a carbonyl group.
- Chen, Manyu,Xia, Jie,Li, Huan,Zhao, Xiuge,Peng, Qingpo,Wang, Jiajia,Gong, Honghui,Dai, Sheng,An, Pengfei,Wang, Haifeng,Hou, Zhenshan
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p. 3801 - 3814
(2021/08/03)
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- Multi-Photocatalyst Cascades: Merging Singlet Oxygen Photooxygenations with Photoredox Catalysis for the Synthesis of Alkaloid Frameworks
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The development of photocascades that rapidly transform simple and readily accessible furan substrates into polycyclic alkaloid frameworks or erythrina natural products is described. Each of the sequences developed makes use of photocatalyzed energy transfer processes, which generate singlet oxygen, to set up the substrates for the second photocatalyzed reaction, wherein electron transfer generates carbon-centered radicals for the cyclizations that give the final complex frameworks. A chemical switch has been developed that can “switch off” one photocatalyst; thus, allowing a second photocatalyst to take over control of the sequence. As a corollary, this strategy represents the first time it has been possible to use multiple photocatalysts in photocascades, and, as such, it expands significantly the reactions that can be included in such cascades and the order in which they can be initiated.
- Kalaitzakis, Dimitris,Bosveli, Artemis,Sfakianaki, Kalliopi,Montagnon, Tamsyn,Vassilikogiannakis, Georgios
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supporting information
p. 4335 - 4341
(2020/12/18)
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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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- 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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- Tuning lipase-catalysed kinetic resolution of 2-substituted thiophenes and furans: A scalable chemoenzymatic route to masked γ-bis-oxo-alcohols
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The demand for greener and applicable approaches aiming at the synthesis of optically active compounds as single enantiomers has seen a significant growth worldwide. Since most of the chemically synthesized compounds are produced as racemates their kinetic resolution has been of great interest. For this purpose a number of chemo-enzymatic approaches were proposed. One of such approaches, the use of isolated lipases, is a well-established alternative. Herein we report the kinetic resolutions of 2-Substituted five-membered heteroaromatic rings. By optimizing the reaction conditions it was possible to produce (2-hydroxy)-2-substituted furans and thiophenes in high enantiomeric ratio (E > 200). Thus, racemic mixtures of compounds with slight structural differences were resolved. The current chemo-enzymatic strategy has been applied to a scalable approach leading to the formation of the enantiopure (S)-2i a well-known building block used for the synthesis of bioactive natural compounds.
- Ferreira, Dartagnan S.P.,Ferreira, Jeiely G.,Filho, Everaldo F.S.,Princival, Jefferson L.
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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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- Effective production of octane from biomass derivatives under mild conditions
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Cool cats dont feel pressure: Furfural is catalytically converted into octane in high yields at relatively low pressures and temperatures. In a three-step process, two bifunctional catalysts, Pt/Co2AlO4 and Pt/NbOPO4, play crucial roles in achieving C8-ols from 4-(2-furyl)-3-buten-2-one and transforming the C8-ols into octane, respectively.
- Xu, Wenjie,Xia, Qineng,Zhang, Yu,Guo, Yong,Wang, Yanqin,Lu, Guanzhong
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experimental part
p. 1758 - 1761
(2012/03/27)
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- N-heterocyclic carbene-catalyzed hydrosilylation of styryl and propargylic alcohols with dihydrosilanes
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Reducing alkenes to tears: Addition of structurally diverse N-heterocyclic carbenes (NHCs) to silicon allows the reduction of propargylic and styryl alcohols through an organocatalyzed silylation/direct hydride transfer tandem reaction (see scheme). Catalytic turnover is enabled by the switch to and from hypervalent silicon. This provides a new synthetic application of NHC-main group element complexes. Copyright
- Zhao, Qiwu,Curran, Dennis P.,Malacria, Max,Fensterbank, Louis,Goddard, Jean-Philippe,Lacote, Emmanuel
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supporting information; experimental part
p. 9911 - 9914
(2011/10/05)
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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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- A novel mesoporous Pd/cobalt aluminate bifunctional catalyst for aldol condensation and following hydrogenation
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A novel mesoporous Pd/cobalt aluminate bifunctional catalyst has been synthesized by a facile co-precipitation process and used in aldol condensation of furfural with acetone and the following hydrogenation of condensation products. This kind of bifunctional catalyst has good activity and can be recycled and regenerated easily. Crown Copyright
- Xu, Wenjie,Liu, Xiaohui,Ren, Jiawen,Zhang, Peng,Wang, Yanqin,Guo, Yanglong,Guo, Yun,Lu, Guanzhong
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experimental part
p. 721 - 726
(2010/07/06)
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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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- Stereoselective debromination and selective reduction of vic-dibromides with nickel boride
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A simple procedure is reported for the stereoselective debromination of vic-dibromides with nickel boride at ambient temperature. Debromination with concomitant reduction of vic-dibromides to give dihydro products in a one-pot reaction is also reported. α,β-Dibromoketones can also be converted to their corresponding alcohols.
- Khurana, Jitender M.,Kandpal, Bhaskar M.,Kukreja, Gagan,Sharma, Purnima
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p. 1019 - 1023
(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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- A Chemoenzymatic Route to (-)-Pyrenophorin
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The key penultimate intermediate, (+)-7(S)-hydroxy-4,4-(ethylenedioxy)oct-2-enoic acid (6a), for the synthesis of (-)-pyrenophorin has been prepared by using a chemoenzymatic approach.
- Ngooi, T.K.,Scilimati, A.,Guo, Zhi-wei,Sih, Charles J.
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p. 911 - 914
(2007/10/02)
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- Synthesis of (+/-) Ethyl (E)-7-Acetoxy-4-oxo-2-octenoate: The Key Synthon of Pyrenophorin
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Starting from furan, which serves as a masked 3-acyl acrylate, (+/-) ethyl (E)-7-acetoxy-4-oxo-2-octenoate (3) has been synthesized.
- Rao, A. V. Rama,Reddy, K. Bal,Dhar, T. G. Murali,Yadav, J. S.
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p. 1014 - 1016
(2007/10/02)
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- FURAN RING AS MASKED 3-ACYLACRYLATE MOIETY. PRACTICAL SYNTHESIS OF RACEMIC (E)4,4(ETHYLENEDIOXY)-7-HYDROXY-2-OCTENOIC ACID, THE C-8 SUBUNIT OF PYRENOPHORIN.
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Furfural and acetone are the staring materials for a new practical synthesis of racemic (E)4,4(ethylenedioxy)-7-hydroxy-2-octenoic acid, the protected C-8 subunit of Pyrenophorin.Furan ring has been used as masked 3-acylacrylate moiety.
- Petrini, Marino,Ballini, Roberto,Rosini, Goffredo,Marotta, Emanuela
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p. 151 - 154
(2007/10/02)
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