- The selective hydrogenation of furfural over intermetallic compounds with outstanding catalytic performance
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The selective hydrogenation of furfural (a biomass-derived platform compound, CO versus CC) is an important reaction for the production of chemical intermediates widely used in the polymer industry. Herein, we report three non-precious intermetallic compounds (IMCs) (Ni3Sn1, Ni3Sn2 and Ni3Sn4) derived from a layered double hydroxide (LDH) precursor, which are characterized by a highly uniform dispersion of IMC nanoparticles and display surprisingly improved catalytic performance toward the selective hydrogenation of furfural (CO) to furfuryl alcohol. In particular, the Ni3Sn2 IMC shows optimal catalytic behavior (conversion: 100%; selectivity: 99%), which exceeds that of reported non-precious metal catalysts and is even comparable to that of noble metal catalysts (e.g., Au, Pd and Pt). A combinative investigation based on in situ FT-IR, XANES and Bader charge studies verifies electron transfer from Sn to Ni, facilitating the activation of adsorption of the CO bond on the Ni top site, whilst inhibiting the adsorption of CC. Both experimental studies (in situ FT-IR and catalytic evaluations) and theoretical calculations (DFT calculations and microkinetic modeling) reveal a vertical adsorption configuration of furfural molecules over the Ni3Sn2 IMC, followed by the first hydrogenation at the carbon atom (the rate-determining step) and the second hydrogenation at the oxygen atom. This detailed study of the structure-selectivity relationship is substantiated by virtue of establishing the adsorption configuration of the substrate and the reaction pathway, which paves the way for the rational design and development of high-efficiency heterogeneous catalysts for selective hydrogenation reactions.
- Yang, Yusen,Chen, Lifang,Chen, Yudi,Liu, Wei,Feng, Haisong,Wang, Bin,Zhang, Xin,Wei, Min
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Read Online
- An iridium-SPO complex as bifunctional catalyst for the highly selective hydrogenation of aldehydes
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A secondary phosphine oxide (SPO) ligand (tert-butyl(phenyl)phosphine oxide) was employed to generate an Ir-SPO complex which shows a particular ability to activate dihydrogen under mild conditions without the help of an external base or additive. Such an iridium(i) complex serves as a precursor for homogeneous catalysis since under H2 it is converted to a mixture of several iridium(iii) hydride species that are the active catalysts. This system was found to be a highly active catalyst for the hydrogenation of substituted aldehydes, giving very high conversions and chemoselectivities for a wide range of substrates. The SPO ligand presumably plays a key role in the catalytic process through heterolytic cleavage of H2 by metal-ligand cooperation. In addition, an exhaustive characterization of the different iridium hydride species was performed by 1D and 2D NMR spectroscopy. The oxidative addition of H2 to the Ir(i)-SPO complex is highly stereoselective, as all generated Ir(iii) hydrides are homochiral. Finally, the crystal structure, as determined by X-ray diffraction, of a dinuclear iridium(iii) hydride complex is described.
- Cano, Israel,Martínez-Prieto, Luis M.,Vendier, Laure,Van Leeuwen, Piet W. N. M.
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Read Online
- Chromium-Catalyzed Production of Diols From Olefins
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Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
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Paragraph 0111
(2021/03/19)
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- Efficient and chemoselective hydrogenation of aldehydes catalyzed by well-defined PN3-pincer manganese(ii) catalyst precursors: An application in furfural conversion
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Well-defined and air-stable PN3-pincer manganese(ii) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the CC double bond/CC triple bond intact. Our methodology was demonstrated for the conversion of biomass derived feedstocks such as furfural and 5-formylfurfural to furfuryl alcohol and 5-(hydroxymethyl)furfuryl alcohol respectively.
- Gholap, Sandeep Suryabhan,Dakhil, Abdullah Al,Chakraborty, Priyanka,Li, Huaifeng,Dutta, Indranil,Das, Pradip K.,Huang, Kuo-Wei
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supporting information
p. 11815 - 11818
(2021/11/30)
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- The formyloxyl radical: Electrophilicity, C-H bond activation and anti-Markovnikov selectivity in the oxidation of aliphatic alkenes
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In the past the formyloxyl radical, HC(O)O, had only been rarely experimentally observed, and those studies were theoretical-spectroscopic in the context of electronic structure. The absence of a convenient method for the preparation of the formyloxyl radical has precluded investigations into its reactivity towards organic substrates. Very recently, we discovered that HC(O)O is formed in the anodic electrochemical oxidation of formic acid/lithium formate. Using a [CoIIIW12O40]5- polyanion catalyst, this led to the formation of phenyl formate from benzene. Here, we present our studies into the reactivity of electrochemically in situ generated HC(O)O with organic substrates. Reactions with benzene and a selection of substituted derivatives showed that HC(O)O is mildly electrophilic according to both experimentally and computationally derived Hammett linear free energy relationships. The reactions of HC(O)O with terminal alkenes significantly favor anti-Markovnikov oxidations yielding the corresponding aldehyde as the major product as well as further oxidation products. Analysis of plausible reaction pathways using 1-hexene as a representative substrate favored the likelihood of hydrogen abstraction from the allylic C-H bond forming a hexallyl radical followed by strongly preferred further attack of a second HC(O)O radical at the C1 position. Further oxidation products are surmised to be mostly a result of two consecutive addition reactions of HC(O)O to the CC double bond. An outer-sphere electron transfer between the formyloxyl radical donor and the [CoIIIW12O40]5- polyanion acceptor forming a donor-acceptor [D+-A-] complex is proposed to induce the observed anti-Markovnikov selectivity. Finally, the overall reactivity of HC(O)O towards hydrogen abstraction was evaluated using additional substrates. Alkanes were only slightly reactive, while the reactions of alkylarenes showed that aromatic substitution on the ring competes with C-H bond activation at the benzylic position. C-H bonds with bond dissociation energies (BDE) ≤ 85 kcal mol-1 are easily attacked by HC(O)O and reactivity appears to be significant for C-H bonds with a BDE of up to 90 kcal mol-1. In summary, this research identifies the reactivity of HC(O)O towards radical electrophilic substitution of arenes, anti-Markovnikov type oxidation of terminal alkenes, and indirectly defines the activity of HC(O)O towards C-H bond activation.
- Iron, Mark A.,Khenkin, Alexander M.,Neumann, Ronny,Somekh, Miriam
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p. 11584 - 11591
(2020/11/23)
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- A Construction of α-Alkenyl Lactones via Reduction Radical Cascade Reaction of Allyl Alcohols and Acetylenic Acids
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An iron-catalyzed cascade reaction of radical reduction of allyl alcohols and acetylenic acids to construct polysubstituted α-alkenyl lactones has been developed. In this paper, various allyl alcohols can form allyl ester intermediates and are further transformed into alkyl radicals, which form products through intramolecular reflex-Michael addition. In addition, this method can be used to prepare spirocycloalkenyl lactones. Interestingly, this protocol can be used to synthesize the skeleton structure of natural products. Moreover, the product can be further transformed into a β-methylene tetrahydrofuran and tetrahydrofuran diene.
- Zhang, Hua,Zhang, Guo-Min,He, Shuai,Shi, Zhi-Chuan,Zhang, Xiao-Mei,Wang, Ji-Yu
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supporting information
p. 8337 - 8344
(2020/11/03)
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- Hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method
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The invention provides a hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method. Various silyl ether protecting groups of nearly 50 kinds of substrates can be efficiently removed in 0.5-16 hours at room temperature by taking 0.02mol%-0.3mol% hafnium trifluoromethanesulfonate as a catalyst, a silyl ether protected hydroxyl compound as a substrate and conventional AR methanol as a solvent. 42 kinds of silyl ether protecting group removing products can be obtained at high yield by performing conventional slica column chromatography purification on a crude product. By regulating the use amount of the catalyst, the Hf(OTf)4 catalyst can realize regioselective removal of 1-degree, 2-degree and 3-degree alkyl TBS and aryl TBS protective groups. Moreover, in a proper equivalent scope, the Hf(OTf)4 catalyst can also realize 1) chemoselective removal of different kinds of silica-based protective groups; and 2) chemoselective removal of 1-degree TBS protective groups under the condition of not affecting a majority of common hydroxyl protective groups.
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Paragraph 0009; 0014
(2019/01/21)
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- Development of a novel secondary phosphine oxide-ruthenium(II) catalyst and its application for carbonyl reduction
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A secondary phosphine oxide-phosphine mixed tridentate ligand and its ruthenium complex have been developed. This complex shows excellent catalytic activity for carbonyl reduction, especially for the reduction of α,β-unsaturated aldehydes. The turnover number and selectivity can reach up to 36500 and 99%, respectively. Control experiments and DFT calculations supported an outer-sphere mechanism during the hydrogenation reaction.
- Tan, Xuefeng,Zeng, Weijun,Zhang, Xiaoyong,Chung, Lung Wa,Zhang, Xumu
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supporting information
p. 535 - 538
(2018/01/19)
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- Selective Base-free Transfer Hydrogenation of α,β-Unsaturated Carbonyl Compounds using iPrOH or EtOH as Hydrogen Source
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Commercially available Ru-MACHOTM-BH is an active catalyst for the hydrogenation of several functional groups and for the dehydrogenation of alcohols. Herein, we report on the new application of this catalyst to the base-free transfer hydrogenation of carbonyl compounds. Ru-MACHOTM-BH proved to be highly active and selective in this transformation, even with α,β-unsaturated carbonyl compounds as substrates. The corresponding aliphatic, aromatic and allylic alcohols were obtained in excellent yields with catalyst loadings as low as 0.1–0.5 mol % at mild temperatures after very short reaction times. This protocol tolerates iPrOH and EtOH as hydrogen sources. Additionally, scale up to multi-gram amounts was performed without any loss of activity or selectivity. An outer-sphere mechanism has been proposed and the computed kinetics and thermodynamics of crotonaldehyde and 1-phenyl-but-2-en-one are in perfect agreement with the experiment.
- Farrar-Tobar, Ronald A.,Wei, Zhihong,Jiao, Haijun,Hinze, Sandra,de Vries, Johannes G.
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supporting information
p. 2725 - 2734
(2018/02/28)
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- Porous, Naturally Derived Hafnium Phytate for the Highly Chemoselective Transfer Hydrogenation of Aldehydes with Other Reducible Moieties
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Both the utilization of naturally occurring compounds to prepare functional materials and the selective conversion of aldehydes with other reducible moieties (ORMs) are very attractive topics. Herein, we synthesized a novel porous material, hafnium phytate (Hf-Phy), by using naturally derived sodium phytate as the building block. Hf-Phy has plenty of mesopores centered around 11.8 nm. Hf-Phy showed excellent performance for the transfer hydrogenation of aldehydes with ORMs by using 2-propanol as the hydrogen source with high selectivities (95–100 %) for alcohols without reducing ORMs. Systematic studies suggested that the oxophilicity of Hf4+ and the basicity and structure of Hf-Phy contributed significantly to the excellent performance. Additionally, Hf-Phy could be used over at least five cycles without any decrease in activity or selectivity.
- Song, Jinliang,Xue, Zhimin,Xie, Chao,Wu, Haoran,Liu, Shuaishuai,Zhang, Lujun,Han, Buxing
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p. 725 - 730
(2018/01/22)
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- Pt/Ferric Hydroxyphosphate: An Effective Catalyst for the Selective Hydrogenation of Α,Β-Unsaturated Aldehydes (Ketones) into Α,Β-Unsaturated Alcohols
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Abstract: Four micro (nano)-sized mesoporous ferric hydroxyphosphates (FHP) are synthesized by a reverse microemulsion-solvothermal method, and then are used as supports to prepare supported Pt catalysts. The mean particle diameter of Pt nanoparticles (NPs) was 4.5–4.6?nm. When the four different Pt/FHP catalysts were used into the hydrogenation of α,β-unsaturated aldehydes (ketones) to their corresponding unsaturated alcohols, Pt/FHP (c) catalyst showed better catalytic performance than the other three partners. Under the optimal experimental conditions, several tested α,β-unsaturated aldehydes could be effectively transformed into corresponding unsaturated alcohols over Pt/FHP (c) catalyst. The catalyst could be recycled and reused several times without activity loss. We propose the stronger interaction between the Pt NPs and ferric ions of the FHP (c) are responsible for its good catalytic performance, and this stronger interaction should be rooted in its enhanced Lewis acid strength.
- Liu, Cheng,Luo, Wei,Liu, Junhua,Sun, Lei,Yang, Yue,Liu, Gui,Wang, Fang,Zhong, Wei,Guild, Curtis,Suib, Steven L.
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p. 555 - 563
(2018/01/11)
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- Selective hydrogenation of unsaturated aldehydes over Pt nanoparticles promoted by the cooperation of steric and electronic effects
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The selective hydrogenation of α,β-unsaturated aldehydes to unsaturated alcohols can reach high selectivity and activity at room temperature using Pt nanoparticles immobilized on a non-porous Al2O3 support stabilized by aspartic acid. Aspartic acid molecules had a significant steric effect on CC hydrogenation and could modify the electronic state of metal particles.
- Liu, Hangyu,Mei, Qingqing,Li, Shaopeng,Yang, Youdi,Wang, Yanyan,Liu, Huizhen,Zheng, Lirong,An, Pengfei,Zhang, Jing,Han, Buxing
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supporting information
p. 908 - 911
(2018/02/07)
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- Tridentate phosphine ligand, catalyst and preparation method and application thereof
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The invention belongs to the field of asymmetric catalysis, and discloses tridentate phosphine ligand which is of a structure of formula I as shown in the specification, wherein R is aryl or substituted aryl. The invention further discloses a catalyst prepared from the ligand. The catalyst is of a structure of formula II as shown in the specification, wherein R is aryl or substituted aryl, and L is mono-phosphine ligand. The invention further discloses application of the catalyst in a catalytic reduction reaction. The invention provides a tridentate phosphine ligand which is novel in structure, and a ruthenium complex of the tridentate phosphine ligand. carbonyl compounds, namely aldehyde and ketone, particularly alpha,beta-unsaturated aldehyde, are reduced by using the ruthenium complex, and very good reaction activity and selectivity are achieved.
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Paragraph 0058-0060
(2017/12/30)
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- BiCl3: A versatile catalyst for the tetrahydropyranylation and depyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric diols
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Bismuth trichloride as mild reagent, has been found to be a worthful catalyst for tetrahydropyranylation of 1°,2°,3°, allylic, benzylic alcohols, and symmetric di-ols. At room temperature the reagent THP(3,4-dihydro-2H-pyran) was successfully employed as pyranylating agent in presence of BiCl3catalyst without the use of a solvent and the yields of the products were found to be 90-96%. Further, the depyranylation of alcohols was achieved in quantitative yield by simple addition of MeOH using the same catalyst. The developed method was showed good chemo-selectivity in symmetrical diols for mono THP protection.
- Vijaya Durga,Balamurali Krishna,Baby Ramana,Santha Kumari,Vijay,Hari Babu
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p. 1030 - 1034
(2017/05/26)
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- Thermoregulated phase-transfer iridium nanoparticle catalyst: Highly selective hydrogenation of the CO bond for α,β-unsaturated aldehydes and the CC bond for α,β-unsaturated ketones
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In the same catalytic system, thermoregulated ligand Ph2P(CH2CH2O)22CH3-stabilized iridium nanoparticles exhibited a totally different orientation for the hydrogenation of unsaturated carbonyl compounds, namely, highly selective hydrogenation of the CO bond for α,β-unsaturated aldehydes and the CC bond for α,β-unsaturated ketones.
- Li, Wenjiang,Wang, Yanhua,Chen, Pu,Zeng, Min,Jiang, Jingyang,Jin, Zilin
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p. 7386 - 7390
(2016/10/21)
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- METHOD FOR PRODUCING UNSATURATED ALCOHOL
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PROBLEM TO BE SOLVED: To provide a method for producing an unsaturated alcohol that uses an unsaturated carbonyl compound as a raw material and can produce an unsaturated alcohol in which only the carbonyl bond of the unsaturated carbonyl compound is selectively reduced with excellent reaction rate, high selectivity and high yield. SOLUTION: The process for producing an unsaturated alcohol includes a step of allowing the reductive reaction of a 3C or more unsaturated carbonyl compound having one or more carbon-carbon unsaturated bonds in the molecule with hydrogen to proceed in the presence of a catalyst comprising at least one kind of metal selected from the group consisting of cobalt, nickel, copper, zinc, ruthenium, rhodium, palladium, silver, osmium, iridium and platinum and at least one kind of metal selected from the group consisting of vanadium, chromium, manganese, iron, molybdenum, tungsten and rhenium to produce a corresponding unsaturated alcohol. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0074-0076
(2017/01/02)
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- Air-stable gold nanoparticles ligated by secondary phosphine oxides for the chemoselective hydrogenation of aldehydes: Crucial role of the ligand
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The synthesis of air-stable and homogeneous gold nanoparticles (AuNPs) employing tert-butyl(naphthalen-1-yl)phosphine oxide as supporting ligand is described via NaBH4 reduction of a Au(I) precursor, [(tert-butyl(naphthalen-1-yl)phosphine oxide)AuCl]2. This highly reproducible and simple procedure furnishes small (1.24 ± 0.16 nm), highly soluble nanoparticles that are found to be highly active catalysts for the hydrogenation of substituted aldehydes, giving high conversions and chemoselectivities for a wide variety of substrates. In addition to catalytic studies the role of the novel stabilizer in the remarkable activity and selectivity exhibited by this system was interrogated thoroughly using a wide range of techniques, including ATR FT-IR, HRMAS NMR, XPS, and EDX spectroscopy. In particular, isotopic labeling experiments enabled us to probe the coordination mode adopted by the SPO ligand bound to the nanoparticle surface by ATR FT-IR spectroscopy. In combination with a series of control experiments we speculate that the SPO ligand demonstrates ligand-metal cooperative effects and plays a seminal role in the heterolytic hydrogenation mechanism.
- Cano, Israel,Chapman, Andrew M.,Urakawa, Atsushi,Van Leeuwen, Piet W. N. M.
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supporting information
p. 2520 - 2528
(2014/03/21)
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- Colloidal gold nanoparticles: An unexpected catalytic activity in aqueous phase with dioxygen
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Selective oxidations of alkenes were investigated using molecular oxygen in aqueous solution under mild conditions. Colloidal gold nanoparticles are particularly versatile catalysts for oxidation reaction with exceptionally high efficiency and significant selectivity. Gold nanorods (Au NRs) exhibited a slightly enhanced activity compare to gold nanospheres.
- Salari, Hadi,Robatjazi, Hossein,Hormozi-Nezhad, Mohammad Reza,Padervand, Mohsen,Gholami, Mohammad Reza
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p. 1219 - 1222
(2014/07/21)
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- Pyrococcus furiosus-mediated reduction of conjugated carboxylic acids: Towards using syngas as reductant
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Pyrococcus furiosus catalyzes the reduction of carboxylic acids to their corresponding alcohols. In addition to hydrogen also carbon monoxide can be used as stoichiometric reductant, paving the way to cheap syngas to promote biocatalytic acid reduction. The enzymes responsible for coupling CO-oxidation to acid reduction are currently unknown but may represent an unprecedented enzyme class. Furthermore, enoate reductase-like activity has been detected in P. furiosus while lacking 'classical' enoate reductases.
- Ni, Yan,Hagedoorn, Peter-Leon,Xu, Jian-He,Arends, Isabel W.C.E.,Hollmann, Frank
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- More efficient redox biocatalysis by utilising 1,4-butanediol as a 'smart cosubstrate'
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1,4-Butanediol is shown to be an efficient cosubstrate to promote NAD(P)H-dependent redox biocatalysis. The thermodynamically and kinetically inert lactone coproduct makes the regeneration reaction irreversible. Thereby not only the molar surplus of cosubstrate is dramatically reduced but also faster reaction rates are obtained.
- Kara, Selin,Spickermann, Dominik,Schrittwieser, Joerg H.,Leggewie, Christian,Van Berkel, Willem J. H.,Arends, Isabel W. C. E.,Hollmann, Frank
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supporting information
p. 330 - 335
(2013/03/29)
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- Ni-In intermetallic nanocrystals as efficient catalysts toward unsaturated aldehydes hydrogenation
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The chemoselective hydrogenation of unsaturated carbonyl compounds is one of the most important and challenging chemical processes in the fine chemical synthesis field, where intermetallic compounds (IMCs) have attracted extensive interest as efficient catalysts. In this work, we demonstrate the preparation of several Ni-In IMCs (Ni3In, Ni2In, NiIn, and Ni 2In3) with a tunable particle size via the utilization of layered double hydroxides (LDHs) precursors that exhibit largely enhanced catalytic activity and selectivity toward the hydrogenation of α,β-unsaturated aldehydes. H2-TPR and semi-in situ XRD measurements reveal a coreduction process in the topotactic transformation of NiIn-LDHs materials to Ni-In IMCs. The catalytic behavior toward various unsaturated carbonyl compounds (e.g., furfural, 1-phenyltanol, crotonaldehyde, and 2-hexenal) can be improved by the modulation of the Ni/In ratio and the particle size of these Ni-In IMCs. For instance, a yield of 99% for the hydrogenation of furfural to furfuryl alcohol was obtained over supported Ni2In catalyst (particle size 5.1 nm, 110 C, 3 MP, 2 h). The XAFS characterization and DFT calculation further reveal the electron transfer and active-site isolation in Ni-In IMCs, accounting for the largely enhanced hydrogenation selectivity. The control over the activity and selectivity of Ni-In IMCs catalysts makes them promising candidates for the chemoselective hydrogenation of unsaturated carbonyl compounds.
- Li, Changming,Chen, Yudi,Zhang, Shitong,Xu, Simin,Zhou, Junyao,Wang, Fei,Wei, Min,Evans, David G.,Duan, Xue
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p. 3888 - 3896
(2013/10/22)
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- Rabbit 3-hydroxyhexobarbital dehydrogenase is a NADPH-preferring reductase with broad substrate specificity for ketosteroids, prostaglandin D2, and other endogenous and xenobiotic carbonyl compounds
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3-Hydroxyhexobarbital dehydrogenase (3HBD) catalyzes NAD(P) +-linked oxidation of 3-hydroxyhexobarbital into 3-oxohexobarbital. The enzyme has been thought to act as a dehydrogenase for xenobiotic alcohols and some hydroxysteroids, but its physiological function remains unknown. We have purified rabbit 3HBD, isolated its cDNA, and examined its specificity for coenzymes and substrates, reaction directionality and tissue distribution. 3HBD is a member (AKR1C29) of the aldo-keto reductase (AKR) superfamily, and exhibited high preference for NADP(H) over NAD(H) at a physiological pH of 7.4. In the NADPH-linked reduction, 3HBD showed broad substrate specificity for a variety of quinones, ketones and aldehydes, including 3-, 17- and 20-ketosteroids and prostaglandin D2, which were converted to 3α-, 17β- and 20α-hydroxysteroids and 9α,11β- prostaglandin F2, respectively. Especially, α-diketones (such as isatin and diacetyl) and lipid peroxidation-derived aldehydes (such as 4-oxo- and 4-hydroxy-2-nonenals) were excellent substrates showing low Km values (0.1-5.9 μM). In 3HBD-overexpressed cells, 3-oxohexobarbital and 5β-androstan-3α-ol-17-one were metabolized into 3-hydroxyhexobarbital and 5β-androstane-3α,17β-diol, respectively, but the reverse reactions did not proceed. The overexpression of the enzyme in the cells decreased the cytotoxicity of 4-oxo-2-nonenal. The mRNA for 3HBD was ubiquitously expressed in rabbit tissues. The results suggest that 3HBD is an NADPH-preferring reductase, and plays roles in the metabolisms of steroids, prostaglandin D2, carbohydrates and xenobiotics, as well as a defense system, protecting against reactive carbonyl compounds.
- Endo, Satoshi,Matsunaga, Toshiyuki,Matsumoto, Atsuko,Arai, Yuki,Ohno, Satoshi,El-Kabbani, Ossama,Tajima, Kazuo,Bunai, Yasuo,Yamano, Shigeru,Hara, Akira,Kitade, Yukio
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p. 1366 - 1375
(2013/11/19)
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- Rapid synthesis of unsaturated alcohols under mild conditions by highly selective hydrogenation
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Ir-ReOx/SiO2 acted as a highly active and selective heterogeneous catalyst for the hydrogenation of unsaturated aldehydes to unsaturated alcohols in water at low H2 pressure (0.8 MPa) and low temperature (303 K). The catalysis is derived from the synergy between Ir metal and ReOx.
- Tamura, Masazumi,Tokonami, Kensuke,Nakagawa, Yoshinao,Tomishige, Keiichi
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supporting information
p. 7034 - 7036
(2013/09/02)
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- Multimetallic Ir-Sn3-catalyzed substitution reaction of π-activated alcohols with carbon and heteroatom nucleophiles
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An atom economic and catalytic substitution reaction of π-activated alcohols by a multimetallic IreSn3 complex has been demonstrated. The multimetallic IreSn3 complex can be easily synthesized from the reaction between [Cp*IrCl2]2 and SnCl2. In presence of as little as 1 mol % of the catalyst three different types of π-activated alcohols, namely benzyl, allyl, and propargyl alcohols, have been successfully transformed into alkylated products using carbon (arenes, heteroarenes, allyltrimethylsilane, and 1,3-dicarbonyls), nitrogen (sulfonamides), oxygen (alcohols), and sulfur (thiols) nucleophiles in very high yields. An electrophilic mechanism is proposed from the Hammett correlation study.
- Maity, Arnab Kumar,Chatterjee, Paresh Nath,Roy, Sujit
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p. 942 - 956
(2013/07/25)
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- Anchoring of copper(II) complexes onto the organically modified MCM-41: Preparation, characterization and catalytic epoxidation
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[Cu(diamine)(NO3)2] complexes have been anchored by substituting easily replaceable nitrate ligand with the amine groups of the organic-modified MCM-41. The amine group containing organic moiety (3-aminopropyl)triethoxysilane has been first anchored on the surface of MCM-41 via silicon alkoxide route. Then the [Cu(diamine)(NO3)2] [where diamine = N,N′-dimethyl-1,2-ethanediamine (NN′dmen) N,N-dimethyl-1,2-ethanediamine (NNdmen), and N,N-diethyl-1,2-ethanediamine (NNdeten)] complex was allowed to react with the modified MCM-41 for tethering the complexes onto mesoporous silica matrix. Copper complexes containing different substituted diamine ligands viz. N,N′-dimethyl-1,2- ethanediamine, N,N-dimethyl-1,2-ethanediamine, and N,N-diethyl-1,2-ethanediamine have also been prepared to compare the catalytic efficiency. The prepared catalysts have been characterized by infrared (FT-IR) and UV-vis spectroscopic, electron paramagnetic resonance (EPR), small-angle X-ray diffraction and N 2 sorption study. The catalytic efficacy in the epoxidation reaction depends on the bulkiness of the substituted group in diamine. Notably, styrene shows an impressive conversion (94%) with tert-butylhydroperoxide (tert-BuOOH) over the Cu(NNdmen)-MCM-41 catalyst. Whereas, conversion in styrene to styrene-oxide reaction were only 78% and 48% with Cu(NNdeten)-MCM-41 and Cu(NN′dmen)-MCM-41 catalysts, respectively.
- Jana, Sreyashi,Bhunia, Susmita,Dutta, Buddhadeb,Koner, Subratanath
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experimental part
p. 225 - 232
(2011/10/19)
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- Properties and tissue distribution of a novel aldo-keto reductase encoding in a rat gene (Akr1b10)
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A recent rat genomic sequencing predicts a gene Akr1b10 that encodes a protein with 83% sequence similarity to human aldo-keto reductase (AKR) 1B10. In this study, we isolated the cDNA for the rat AKR1B10 (R1B10) from rat brain, and examined the enzymatic properties of the recombinant protein. R1B10 utilized NADPH as the preferable coenzyme, and reduced various aldehydes (including cytotoxic 4-hydroxy-2-hexenal and 4-hydroxy- and 4-oxo-2-nonenals) and α-dicarbonyl compounds (such as methylglyoxal and 3-deoxyglucosone), showing low Km values of 0.8-6.1μM and 3.7-67μM, respectively. The enzyme also reduced glyceraldehyde and tetroses (Km=96-390μM), although hexoses and pentoses were inactive and poor substrates, respectively. Among the substrates, 4-oxo-2-nonenal was most efficiently reduced into 4-oxo-2-nonenol, and its cytotoxicity against bovine endothelial cells was decreased by the overexpression of R1B10. R1B10 showed low sensitivity to aldose reductase inhibitors, and was activated to approximately two folds by valproic acid, and alicyclic and aromatic carboxylic acids. The mRNA for R1B10 was expressed highly in rat brain and heart, and at low levels in other rat tissues and skin fibroblasts. The results suggest that R1B10 functions as a defense system against oxidative stress and glycation in rat tissues.
- Endo, Satoshi,Matsunaga, Toshiyuki,Kuragano, Tsukasa,Ohno, Satoshi,Kitade, Yukio,Tajima, Kazuo,El-Kabbani, Ossama,Hara, Akira
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experimental part
p. 230 - 237
(2011/10/30)
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- Selective Reduction of C=O in α,β-Unsaturated Carbonyls through Catalytic Hydrogen Transfer Reaction over Mixed Metal Oxides
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Selective reduction of α,β-unsaturated carbonyls was studied over CoO-ZrO2 using propan-2-ol as a hydrogen donor and KOH as promoter in a liquid phase reaction. The catalyst used for this synthetically useful transformation showed considerable level of reusability as well as good activity.
- Sonavane, Sachin U.,Jayaram, Radha V.
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p. 146 - 148
(2007/10/03)
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- Chemoselective reduction of α,β-unsaturated carbonyls over novel mesoporous CoHMA molecular sieves under hydrogen transfer conditions
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Chemoselective reduction of α,β-unsaturated carbonyls to the corresponding alcohols was achieved by a catalytic transfer hydrogenation (CTH) method using cobalt(II)-substituted hexagonal mesoporous aluminophosphate (CoHMA) molecular sieve catalyst. Further, the catalyst was found to be promising as a heterogeneous catalyst as the yield was practically unchanged after up to six cycles.
- Selvam,Sonavane,Mohapatra,Jayaram
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p. 542 - 544
(2007/10/03)
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- Electrocatalytic hydrogenation of organic compounds using current density gradient and sacrificial anode of nickel
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Preparative electrocatalytic hydrogenation (ECH) of some organic compounds were performed: cyclohexene, 2-cyclohexen-1-one, benzaldehyde, acetophenone, styrene, 1,3-cyclohexadiene, trans-trans-2,4-hexadien-1-ol, citral, linalool and geraniol. H2O/MeOH (1:1), NH4OAc or NH4Cl (0.2 M) were used as solvent and supporting electrolyte. A sacrificial anode of nickel allowed the use of an undivided cell, with a cell voltage varying between 2.3 and 1.3 V, depending on the supporting electrolyte. A current density gradient was applied to diminish the time of reaction and obtain a good electrochemical efficiency. An in situ prepared cathode of nickel deposited on iron provided a highly efficient ECH process, and the constant deposition of nickel on the electrode surface avoided catalyst poisoning. The ECH system was somewhat selective, hydrogenating conjugated olefins in good yield.
- Santana, Diogo S.,Lima, Márcio V. F.,Daniel, Jorge R. R.,Navarro, Marcelo
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p. 4725 - 4727
(2007/10/03)
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- Modified Borohydride Agents, 1-Benzyl-4-aza-1-azoniabicyclooctane Tetrahydroborate (BAAOTB) versus Tetrabutylammonium Tetrahydroborate (TBATB). Efficient, Selective, and Versatile Reducing Agents
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1-Benzyl-4-aza-1-azoniabicyclooctane tetrahydroborate (BAAOTB) and tetrabutylammonium tetrahydroborate (TBATB) are used for the selective reductions of aldehydes, ketones, α,β-unsaturated carbonyl compounds, acid chlorides, azides, epoxides, and disulfides in t-BuOH and hexane/chloroform.ABBOAB with its rigid and bulky structure reacts more selectively than its analogue TBATB.
- Firouzabadi, Habib,Afsharifar, Gholam Reza
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p. 2595 - 2602
(2007/10/03)
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- Highly Diastereoselective Synthesis of Substituted Epichlorohydrins and Regioselective Preparation of Allyl Alcohols using Chloro or Idomethyllithium
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Substituted epichlorohydrins 3 or 6 are obtained α-bromo or α-chlorocarbonyl compounds (1 or 4) and chloro or iodomethyllithium, respectively.Starting from α-bromocarbonyl compounds 1 or acyclic α-chloro ketones the reaction takes place with total diastereoselectivity.Treatment of epichlorohydrins 3 or 6 with lithium iodide affords the same substituted allyl alcohols 7 in a regioselective manner.A mechanism to explain this transformation is proposed.Regioisomeric allyl alcohols 11 are prepared by reaction of epichlorohydrins 6 with lithium powder.
- Concellon, Jose M.,Llavona, Lujan,Bernad, Pablo L. Jr.
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p. 5573 - 5584
(2007/10/02)
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- EFFICIENT AND REGIOCONTROLLED NICKEL(II)-CATALYZED ALKYLATION OF 2-ALKYL-1,3-DIOXEP-4-ENES BY GRIGNARD REAGENTS: A SIMPLE ROUTE TO ALLYLIC ALCOHOLS
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The regio- and the stereochemistries of the NidppeCl2 catalyzed alkylation of 2-alkyl-1,3-dioxep-4-enes by Grignard reagents are not affected by the nature of the C2 substituent; in any case, allylic alcohols are the main reaction products and nearly pure Z isomers are almost quantitatively obtained when either secondary or tertiary Grignard reagents are used.A rationale for the reaction is proposed.
- Malanga, Corrado,Menicagli, Rita,Lardicci, Luciano
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- Preparation and Some Reactions of Allylic Indium Reagents
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A variety of allylic indium sesquihalides were readily prepared by the reaction of indium powder with allylic halides in DMF at room temperature.Protonation of the allylindium reagents proceeded regiospecifically at the γ-position of the allylic group to give 1-propenes.A facile transformation of α-pinene to β-pinene was achieved via a myrtenylindium intermediate.Oxygenation of the allylic indium reagents gave mixtures of allylic alcohol isomers in moderate yields.The coupling of the allylindium reagents with cyclic imides gave diverse products depending on the structures of the substrates and the reagents.Stannylation with tributylchlorostannane occurred exclusively at the α-carbon, yielding allyltributylstannanes; E,Z isomerization of the allylic double bond depended largely upon the substitution pattern on the allylic moiety.
- Araki, Shuki,Shimizu, Toshio,Johar, Perminder S.,Jin, Shun-Ji,Butsugan, Yasuo
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p. 2538 - 2542
(2007/10/02)
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