- Ru(iii) -based polyoxometalate tetramers as highly efficient heterogeneous catalysts for alcohol oxidation reactions at room temperature
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A novel ruthenium-containing polyoxometalate-based organic-inorganic hybrid, K4Na9H7.4[(AsW9O33)4(WO2)4{Ru3.2(C3H3N2)2}]·42H2O (1), was successfully synthesized by a one-step hydrothermal method under acidic conditions, which applied a self-assembly strategy between inorganic polyoxometalate based on trivacant [B-α-AsW9O33]9?{AsW9} fragments and an organic ligand, imidazole (C3H4N2). Compound1was further characterized by single-crystal X-ray diffraction, PXRD, IR spectroscopy, UV-Vis spectroscopy, ESI-MS, elemental analysis and TGA. Single-crystal X-ray diffraction data reveal that the polyanion consists of four trivacant Keggin-type polyanion {AsW9} building blocks bridged by four {WO6} units, leading to a crown-shaped tetrameric structure [(AsW9O33)4(WO2)4{Ru3.2(C3H3N2)2}]20.4?. The ESI-MS result reveals that the polyanion unit has excellent structural integrity in water. Moreover, the catalysis study of1was also further investigated, and the experimental results indicate heterogeneous catalyst1presents high efficiency (yield = 98%), excellent selectivity (>99%), and good recyclability for the oxidation of 1-(4-chlorophenyl)ethanol to 4′-chloroacetophenone with commercially available 70% aqueoustert-butyl hydroperoxide {TBHP (aq.)} as the oxidant at room temperature.
- Li, Huafeng,Ma, Pengtao,Niu, Jingyang,Song, Junpeng,Wang, Jingping,Wang, Yaqiong,Zhao, Xue,Zou, Yan
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p. 12664 - 12673
(2021/09/28)
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- Hydration of Alkynes to Ketones with an Efficient and Practical Polyoxomolybdate-based Cobalt Catalyst
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Hydration of alkynes to ketones is one of the most atom economical and universal methods for the synthesis of carbonyl compounds. However, the basic reaction usually requires organic ligand catalysts or harsh reaction conditions to insert oxygen into the C≡C bond. Here, we report an inorganic ligand supported cobalt (III) catalyst, (NH4)3[CoMo6O18(OH)6], which is supported by a central cobalt (III) mononucleus and a ring-shaped pure inorganic ligand composed of six MoVIO6 octahedrons to avoid the disadvantages of expensive and unrecyclable organic ligand catalysts or noble metal catalysts. Under mild conditions, the cobalt (III) catalyst can be used for the hydration of alkynes to ketones. The catalyst is non-toxic, green, and environment friendly. The catalyst can be recycled at least six times with high activity. According to control experiments, a reasonable mechanism is provided.
- Xie, Ya,Wang, Jingjing,Wang, Yunyun,Han, Sheng,Yu, Han
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p. 4985 - 4989
(2021/10/12)
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- The effect of the position of cross-linkers on the structure and microenvironment of PPh3moiety in porous organic polymers
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Three trivinyl functionalization triphenylphosphine (3vPPh3)-based porous organic ligands (3vPPh3-POLs) with cross-linkers in different positions were obtained through solvothermal polymerization. By simply changing the position of the cross-linkers (vinyl groups) attached to the PPh3monomer, the resulting porous organic polymer (POP) materials acquired diverse hierarchical porous structures, and the microenvironment of POPs was sequently regulated. Among the three 3vPPh3-POLs, the BET surface areas ranged from 168 to 1583 m2g?1, while the proportion of micropores changed from 0.0% to 52.0%. Benefiting from the unique structure, Rh ions could be coordinated and dispersed as a single site inm-3vPPh3-POL to form HRh(CO)2(PPh3-POL)2species, which endowed the Rh/m-3vPPh3-POL catalyst with an activity similar to that in the homogeneous system, anl/bratio (the ratio of the linear aldehyde to the branched aldehyde) approximately as high as 10, and stability for a duration of more than 500 h in the hydroformylation of 1-octene.
- Ji, Guangjun,Li, Cunyao,Xiao, Dong,Wang, Guoqing,Sun, Zhao,Jiang, Miao,Hou, Guangjin,Yan, Li,Ding, Yunjie
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p. 9165 - 9174
(2021/04/16)
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- Production of chiral alcohols from racemic mixtures by integrated heterogeneous chemoenzymatic catalysis in fixed bed continuous operation
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Valuable chiral alcohols have been obtained from racemic mixtures with an integrated heterogeneous chemoenzymatic catalyst in a two consecutive fixed catalytic bed continuous reactor system. In the first bed the racemic mixture of alcohols is oxidized to the prochiral ketone with a Zr-Beta zeolite and using acetone as the hydrogen acceptor. In the second catalytic bed the prochiral ketone is stereoselectively reduced with an alcohol dehydrogenase (ADH) immobilized on a two dimensional (2D) zeolite. In this process, the alcohol (isopropanol) formed by the reduction of acetone in the first step reduces the cofactor in the second step, and the full reaction cycle is in this way internally closed with 100% atom economy. A conversion of about 95% with ~100% selectivity to either the (R) or the (S) alcohol has been obtained for a variety of racemic mixtures of alcohols.
- Carceller, Jose Miguel,Climent, Maria J.,Corma, Avelino,Iborra, Sara,Mifsud, Maria
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p. 2767 - 2777
(2020/06/17)
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- Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β-Unsaturated Ketones
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Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β-unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β-unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4-selective hydroboration, providing a straightforward and stereoselective route to rare syn-aldol products in one-pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.
- Beltran, Frédéric,Bergamaschi, Enrico,Funes-Ardoiz, Ignacio,Teskey, Christopher J.
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supporting information
p. 21176 - 21182
(2020/09/17)
-
- Selective oxidation of exogenous substrates by a bis-Cu(III) bis-oxide complex: Mechanism and scope
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Cu(III)2(μ-O)2 bis-oxides (O) form spontaneously by direct oxygenation of nitrogen-chelated Cu(I) species and constitute a diverse class of versatile 2e?/2H+ oxidants, but while these species have attracted attention as biomimetic models for dinuclear Cu enzymes, reactivity is typically limited to intramolecular ligand oxidation, and systems exhibiting synthetically useful reactivity with exogenous substrates are limited. OTMPD (TMPD = N1, N1, N3, N3-tetramethylpropane-1,3-diamine) presents an exception, readily oxidizing a diverse array of exogenous substrates, including primary alcohols and amines selectively over their secondary counterparts in good yields. Mechanistic and DFT analyses suggest substrate oxidation proceeds through initial axial coordination, followed by rate-limiting rotation to position the substrate in the Cu(III) equatorial plane, whereupon rapid deprotonation and oxidation by net hydride transfer occurs. Together, the results suggest the selectivity and broad substrate scope unique to OTMPD are best attributed to the combination of ligand flexibility, limited steric demands, and ligand oxidative stability. In keeping with the absence of rate-limiting C–H scission, OTMPD exhibits a marked insensitivity to the strength of the substrate Cα–H bond, readily oxidizing benzyl alcohol and 1-octanol at near identical rates.
- Large, Tao A.G.,Mahadevan, Viswanath,Keown, William,Stack, T. Daniel P.
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p. 782 - 792
(2019/01/03)
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- A Stable Polyoxometalate-Based Metal-Organic Framework as Highly Efficient Heterogeneous Catalyst for Oxidation of Alcohols
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A novel copper-containing 3D polyoxometalate-based metal-organic framework (POMOF), H[Cu5ICuII(pzc)2(pz)4.5{P2W18O62}]·6H2O (HENU-1, HENU = Henan University; Hpzc = pyrazine-2-carboxylic acid, pz = pyrazine), was successfully isolated by a one-step hydrothermal method. In this compound, the {P2W18} polyanion acts as a seven-connected linker bridging adjacent 2D double-layer networks, as well as a template to induce the formation of the desired 3D framework. Particularly, the pz ligands are generated from pzc ligands in situ during the reaction process. HENU-1 exhibits not only good stability in air but also tolerance to acidic and basic media. It was first employed as a highly efficient heterogeneous catalyst for the oxidation of 1-phenylethanol into acetophenone, which shows 97% yield using tert-butyl hydroperoxide as oxidant with a turnover frequency of up to 9690·h-1, and was reused for at least five cycles without significant catalytic activity loss. No POM leaching or framework decomposition was observed in our study.
- Li, Dandan,Xu, Qiaofei,Li, Yingguang,Qiu, Yueting,Ma, Pengtao,Niu, Jingyang,Wang, Jingping
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p. 4945 - 4953
(2019/04/25)
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- Pyrazine dicarboxylate-bridged arsenotungstate: Synthesis, characterization, and catalytic activities in epoxidation of olefins and oxidation of alcohols
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A praseodymium(iii)-containing arsenotungstate K16H15Li7[Pr2(H2O)3(pzdc)As3W29O103]2·38H2O (1) (pzdc = pyrazine-2,3-dicarboxylic acid) was synthesized by a conventional aqueous solution method and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), and single crystal X-ray diffraction. Structural analysis revealed that compound 1 was constructed by two identical subunits {Pr2(H2O)3(AsW9O33)3W2O4} bridged together by two pzdc ligands. In addition, compound 1 could act as an efficient catalyst for the epoxidation of olefins and oxidation of alcohols with hydrogen peroxide (H2O2) as the oxidant. In particular, the turnover frequency (TOF) in the oxidation of 1-phenylethanol reached up to 10170 h-1, which is higher than that of previously reported catalysts.
- Ma, Xinyi,He, Peipei,Xu, Baijie,Lu, Jingkun,Wan, Rong,Wu, Hechen,Wang, Yuan,Ma, Pengtao,Niu, Jingyang,Wang, Jingping
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p. 12956 - 12963
(2019/09/07)
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- Polyoxovanadate catalysts for oxidation of 1-phenyl ethanol: From the discrete [V4O12]4- and [V10O28]6- anions to the anionic [V6O17]:N4 n - Coordination polymer
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Three polyoxovanadate-based hybrids {[Ru(phen)3]2[V4O12]}·13H2O (1), [Ru(phen)3]2[V10O28]·15H2O (2), and [Ru(phen)3]2[V6O17]Cl·11H2O (3) (phen = 1,10-phenanthroline) were prepared under hydrothermal conditions and characterized by electron paramagnetic resonance (EPR) spectroscopy, infrared spectroscopy (IR), powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis, X-ray photoelectron spectroscopy (XPS), and single crystal X-ray diffraction analysis. Although the structures of both the cyclic vanadate [V4O12]4- and the [V10O28]6- anions are well-known, interestingly, a novel 1-dimensional (1-D) coordination polymer [V6O17]n4n- anion was constructed from tetranuclear [V4O12]4- and dinuclear [V2O7]4- building blocks, which were linked alternately through corner-shared oxygen atoms. Furthermore, the negative charges of polyoxovanadate [V4O12]4-, [V10O28]6- and [V6O17]4- anions were balanced by two [Ru(phen)3]2+/3+ complex cations. The catalytic properties of compounds 1-3 for the oxidation of 1-phenyl ethanol by tert-butyl hydroperoxide (TBHP) were investigated, and the results demonstrated that 1 and 3 exhibited excellent catalytic activities for the oxidation of 1-phenyl ethanol under mild catalytic conditions.
- Wang, Ke,Xu, Qiaofei,Ma, Pengtao,Zhang, Chao,Wang, Jingping,Niu, Jingyang
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p. 6273 - 6279
(2018/10/23)
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- Copper based coordination polymers based on metalloligands: Utilization as heterogeneous oxidation catalysts
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This work presents the synthesis and characterization of two Cu(ii)-based coordination polymers prepared by utilizing two different Co(iii)-based metalloligands offering appended arylcarboxylic acid groups. Both coordination polymers are three-dimensional in nature and present pores and channels filled with water molecules. Both coordination polymers function as heterogeneous catalysts for the epoxidation of various olefins using O2 while employing isobutyraldehyde as the coreductor and for peroxide-mediated oxidation of assorted benzyl alcohols. The catalytic results illustrate efficient oxidation reactions, whereas the hot-fltration test and leaching experiments indicate the true heterogeneous nature of the catalysis.
- Kumar, Gulshan,Hussain, Firasat,Gupta, Rajeev
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p. 16985 - 16994
(2019/01/03)
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- 2-AMINO-1,3,4-THIADIAZINE AND 2-AMINO-1,3,4-OXADIAZINE BASED ANTIFUNGAL AGENTS
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The invention provides a compound which is a diazine of formula (I) or a tautomer thereof, or a pharmaceutically acceptable salt thereof, for use as an antifungal agent: (I) wherein X, N', C', A and E are as defined herein. The invention also provides a compound of Formula (I) as defined herein.
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Page/Page column 56
(2017/02/09)
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- Cooperative Electrocatalytic and Chemoselective Alcohol Oxidation by Shvo's Catalyst
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A new electrocatalytic conversion of alcohols to ketones and aldehydes was developed based on an electrochemical study of Shvo's complex. The oxidation of secondary alcohols was efficiently performed under mild conditions using a catalytic amount of Shvo's catalyst, in combination with a sub-stoichiometric amount of 2,6-dimethoxy-1,4-benzoquinone in N,N-dimethylformamide at 80 °C. The hydroquinone thus formed is continuously reoxidized with the aid of an electrochemical device. Excellent yields for different ketones, aromatic as well as aliphatic and α,β-unsaturated ketones, are obtained. In addition, chemoselectivity towards oxidation of the secondary alcohol is achieved when converting vicinal diols such as 1,2-octanediol and 1,2-decanediol. (Figure presented.).
- Lybaert, Jeroen,Trashin, Stanislav,Maes, Bert U. W.,De Wael, Karolien,Abbaspour Tehrani, Kourosch
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supporting information
p. 919 - 925
(2017/03/27)
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- Dimeric Ruthenium(II)-NNN Complex Catalysts Bearing a Pyrazolyl-Pyridylamino-Pyridine Ligand for Transfer Hydrogenation of Ketones and Acceptorless Dehydrogenation of Alcohols
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Dimeric pincer-type ruthenium(II)-NNN complexes bearing an unsymmetrical pyrazolyl-pyridylamino-pyridine ligand were prepared and characterized by NMR, elemental analysis, and X-ray single crystal structural determination. These complexes exhibited very high catalytic activity for both transfer hydrogenation of ketones and acceptorless dehydrogenation of secondary alcohols, achieving TOF values up to 1.9 × 106 h-1 in the transfer hydrogenation of ketones. The high catalytic activity of the Ru(II) complex catalysts is attributed to the presence of the unprotected NH functionality in the ligand and hemilabile unsymmetrical coordination environment around the central metal atoms in the complex.
- Wang, Qingfu,Chai, Huining,Yu, Zhengkun
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p. 3638 - 3644
(2017/10/03)
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- Mediated electrolysis of vicinal diols by neocuproine palladium catalysts
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Synthetic electrochemistry agrees well with the principles of sustainable chemistry, therefore it is considered as a more environmentally friendly approach than some current synthetic methods. Here, we present a new strategy for the chemoselective oxidation of vicinal diols, viz. the integration of neocuproine palladium catalysts and electrosynthesis. Benzoquinones are used as an effective mediator as the reduced species (hydroquinones) can be easily reoxidized at relative low potentials at an electrode surface. NeocuproinePd(OAc)2 efficiently works as a catalyst in an electrolysis reaction for vicinal diols at room temperature. This is a remarkable observation given the fact that aerobic oxidation reactions of alcohols typically need a more complex catalyst, i.e. [neocuproinePdOAc]2[OTf]2. In this article we describe the optimization of the electrolysis conditions for the neocuproinePd(OAc)2 catalyst to selectively oxidize diols. The suggested approach leads to conversion of alcohols with high yields and provides an interesting alternative to perform oxidation reactions under mild conditions by the aid of electrochemistry.
- Lybaert,Tehrani, K. Abbaspour,De Wael
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p. 685 - 691
(2017/07/22)
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- Dehydrocyclization of C6 Hydrocarbon with and Without Oxygen Containing Substituent over Pt/(Na)-Al2O3 Catalyst
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The presence of hydroxyl or keto functional group affects both activity and selectivity for dehydrocyclization of C6 hydrocarbon over Pt/(Na)-Al2O3 catalyst. Under similar reaction conditions, n-hexane produces benzene as the primary product (>40 %), whereas dehydration is a major reaction pathway for 2-hexanol and yields mainly hexenes (>70 %). However, 2-hexanone was found to be involved in a variety of reactions over Pt/(Na)-Al2O3 catalyst and produces lower hydrocarbons (C2-C5), 5-dodecanone, 2- And 5-nonanones, and 2-acetyl-3-propyl-2-cyclohexen-1-one. The presence of hydroxyl (-OH) or keto group (=C=O) at the C-2 position alters the interaction of C6 hydrocarbon with the catalyst surface which eventually controls the overall product selectivity.
- Gnanamani, Muthu Kumaran,Shafer, Wilson D.,Keogh, Robert A.,Davis, Burtron H.
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p. 424 - 432
(2016/02/23)
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- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
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The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
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The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
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- A novel dinuclear schiff base copper complex as an efficient and cost effective catalyst for oxidation of alcohol: Synthesis, crystal structure and theoretical studies
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An environmentally friendly protocol is described for an economic, practical laboratory-scale oxidation of primary and secondary alcohols to aldehydes and ketones, using a bis-chloro-bridged binuclear Cu(II) complex [(HL)Cu(μ 2-Cl)2Cu(HL)] 1.5 CH3OH as catalyst. The catalyst was prepared in situ from commercially available reagents and is characterized by single crystal X-ray analysis, FT-IR, UV-visible spectra, mass spectrometry, and powder x-ray diffraction (PXRD). The geometry of the complex has been optimized using the B3LYP level of theory confirming the experimental data. Our results demonstrated well the efficiency, selectivity and stability of this new catalyst in the oxidation of alcohols in ethanol and tert-butyl hydroperoxide (tBuOOH) as a green solvent and oxidant, respectively. Turnover number and reusability have proven the high efficiency and relative stability of the catalyst. [Figure not available: see fulltext.]
- Naeimi, Atena,Saeednia, Samira,Yoosefian, Mehdi,Rudbari, Hadi Amiri,Nardo, Viviana Mollica
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p. 1321 - 1328
(2015/10/06)
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- Synthesis, characterization, reactivity and catalytic activity of a novel chiral manganese Schiff base complex
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A new chiral linear tetramine (N1-(1-(2-aminophenylamino)propan-2-yl)benzene-1,2-diamine), CLT, and its Schiff base ligand, which was derived from CLT with 2-hydroxybenzaldehyde, was synthesized and transformed into the corresponding manganese(iii) complex. The Schiff base ligand was studied by 1H NMR, 13C NMR, COSY, HSQC, DEPT and microanalysis. Density functional theory (DFT) calculations were performed to determine the structure of the [MnIIIL]+ complex. This manganese complex catalyzes the oxidation of alcohols using 30% H2O2 as an oxidant. Over-oxidation of aldehydes to carboxylic acid and the formation of by-products was not observed. α-β unsaturated alcohol was oxidized smoothly without the oxidation of the double bond.
- Azadbakht, Reza,Amini Manesh, Abbas,Malayeri, Mahdieh,Dehghani, Behzad
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p. 6459 - 6464
(2015/08/06)
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- Porous polymerized organocatalysts rationally synthesized from the corresponding vinyl-functionalized monomers as efficient heterogeneous catalysts
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Porous polymerized organocatalysts (PPOs) have been successfully synthesized from the corresponding vinyl-functionalized monomers under solvothermal conditions. These PPOs have high surface areas, large pore volumes, hierarchical porosity, and good stability. Utilized as a typical organocatalyst, the porous polymerized 2,2,6,6-tetramethylpiperidine-1-oxyl (PPO-TEMPO) with stable free radicals shows high activities and excellent recyclabilities in selective oxidations of a variety of alcohols to the corresponding aldehydes or ketones. This synthesis method may open a new door for developing heterogeneous catalysts with high activity and good recyclability in the future.
- Huangfu, Ying,Sun, Qi,Pan, Shuxiang,Meng, Xiangju,Xiao, Feng-Shou
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p. 1556 - 1559
(2015/03/14)
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- Regioselective Isomerization of 2,3-Disubstituted Epoxides to Ketones: An Alternative to the Wacker Oxidation of Internal Alkenes
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We report an alternative pathway to the Wacker oxidation of internal olefins involving epoxidation of trans-alkenes followed by a mild and highly regioselective isomerization to give the major ketone isomers in 66-98% yield. Preliminary kinetics and isotope labeling studies suggest epoxide ring opening as the turnover limiting step in our proposed mechanism. A similar catalytic system was applied to the kinetic resolution of select trans-epoxides to give synthetically useful selectivity factors of 17-23 for benzyl-substituted substrates.
- Lamb, Jessica R.,Mulzer, Michael,Lapointe, Anne M.,Coates, Geoffrey W.
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supporting information
p. 15049 - 15054
(2015/12/08)
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- Synthesis and Structural Reassignment of Plakinidone
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In connection with its first synthesis, plakinidone was structurally revised to a five-membered lactone. The key evidence for the previous assignment of this natural product as a perlactone was proven to be a misinterpretation of the MS data because of unawareness of a facile air oxidation. The synthetic samples also allowed for detection of differences in 13C NMR for diastereomers of remote stereogenic centers, along with the influence of the air oxidation on the optical rotation.
- Xu, Ze-Jun,Tan, Dong-Xing,Wu, Yikang
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p. 5092 - 5095
(2015/11/03)
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- Dynamic Release-Immobilization of a Homogeneous Rhodium Hydroformylation Catalyst by a Polyoxometalate Metal-Organic Framework Composite
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Thermal treatment of phosphotungstic acid (PTA)-MIL-101(Cr) composites in the presence of hydroformylation catalyst RhH(CO)(PPh3)3 leads to immobilization of the homogeneous Rh complex within the metal-organic framework (MOF) scaffold by coordination of PTA-Rh. The Rh complex-containing MOFs are tested in the hydroformylation of 1-octene in which PTA competes with CO during ligand association. In the presence of the carbonyl ligand, the Rh complex is released from the MOF and behaves as a homogeneous catalyst. Therefore, the product spectra and selectivities of the Rh complex-containing MOFs are similar to those of RhH(CO)(PPh3)3. Upon CO evacuation, Rh recoordinates to PTA, allowing for easy recycling of this new pseudo-heterogeneous catalyst.
- Sartipi, Sina,Valero Romero, Maria Jose,Rozhko, Elena,Que, Zhenyang,Stil, Hans A.,De With, Jan,Kapteijn, Freek,Gascon, Jorge
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p. 3243 - 3247
(2015/10/28)
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- Manganese- and cobalt-based coordination networks as promising heterogeneous catalysts for olefin epoxidation reactions
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We demonstrate the synthesis of Mn2+- and Co2+-based coordination networks using two Co3+-based metalloligands differing by the position of the appended arylcarboxylate groups. The structural analyses reveal topologically distinct networks with pores of variable dimensions allowing facile diffusion of substrates and/or reagents. All four networks function as heterogeneous catalysts for the olefin epoxidation reactions using tert-butyl-hydroperoxide without any requirement of solvent or additive. Control and optimization experiments illustrate recyclable network-based catalysts that make them attractive candidates for the "greener" oxidation chemistry processes.
- Kumar, Girijesh,Kumar, Gulshan,Gupta, Rajeev
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p. 2603 - 2615
(2015/03/30)
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- Practical Cu(OAc)2/TEMPO-catalyzed selective aerobic alcohol oxidation under ambient conditions in aqueous acetonitrile
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We reported a ligand-and additive-free Cu(OAc)2/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary and secondary benzylic alcohols, primary and secondary 1-heteroaryl alcohols, cinnamyl alcohols, and aliphatic alcohols to the corresponding aldehydes and ketones. This ambient temperature oxidation protocol is of practical features like aqueous acetonitrile as solvent, ambient air as the terminal oxidant, and low catalyst loading, presenting a potential value in terms of both economical and environmental considerations. Based on the experimental observations, a plausible reaction mechanism was proposed.
- Jiang, Jian-An,Du, Jia-Lei,Wang, Zhan-Guo,Zhang, Zhong-Nan,Xu, Xi,Zheng, Gan-Lin,Ji, Ya-Fei
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supporting information
p. 1677 - 1681
(2014/03/21)
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- A reusable unsupported rhenium nanocrystalline catalyst for acceptorless dehydrogenation of alcohols through γ-C-H activation
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Rhenium nanocrystalline particles (Re NPs), of 2 nm size, were prepared from NH4ReO4 under mild conditions in neat alcohol. The unsupported Re NPs convert secondary and benzylic alcohols to ketones and aldehydes, respectively, through catalytic acceptorless dehydrogenation (AD). The oxidant- and acceptor-free neat dehydrogenation of alcohols to obtain dihydrogen gas is a green and atom-economical process for making carbonyl compounds. Secondary aliphatic alcohols give quantitative conversion and yield. Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Re K-edge X-ray absorption near-edge structure (XANES), and X-ray absorption fine structure (EXAFS) data confirmed the characterization of the Re NPs as metallic rhenium with surface oxidation to rhenium(IV) oxide (ReO2). Isotope labeling experiments revealed a novel γ-CH activation mechanism for AD of alcohols. Active particles: A rhenium nanoparticle (Re NP) catalyst is generated from NH4ReO4 under mild solution conditions in neat 3-octanol at 180°C. The resulting Re NPs catalyze acceptorless dehydrogenation of alcohols through a novel C-H activation pathway, and are fully recyclable. Copyright
- Yi, Jing,Miller, Jeffrey T.,Zemlyanov, Dmitry Y.,Zhang, Ruihong,Dietrich, Paul J.,Ribeiro, Fabio H.,Suslov, Sergey,Abu-Omar, Mahdi M.
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supporting information
p. 833 - 836
(2014/01/23)
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- METHOD FOR THE PURPOSE OF A CATALYTIC CONDENSATION OR COUPLING
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The invention relates to a method for catalytically condensing organic compounds containing at least one oxo and/or hydroxyl function into CH acidic compounds and/or coupling said organic compounds to the CH acidic compounds in the presence of a catalyst which comprises an active carbon substrate provided with a metal. The method is suitable in particular for generating higher alcohols, aldehydes, ketones, and/or alkanes as well as mixtures thereof.
- -
-
Paragraph 0215-0222
(2014/12/09)
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- Mononuclear complexes of amide-based ligands containing appended functional groups: Role of secondary coordination spheres on catalysis
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Amide-based ligands H2L1, H2L2 and H2L3 containing thiazole, thiazoline and benzothiazole appended groups have been used to synthesize Zn2+ (1 and 3), Cd2+ complexes (2 and 4), and a Mn2+ complex (5). In all cases, potentially multidentate ligands create a meridional N3 coordination environment around the M(ii) ion whereas additional sites are occupied by labile nitrate ions in 1-4 and MeOH in 5. Interestingly, metal complexation caused the migration of protons from amidic N-H sites to the appended heterocyclic rings in complexes 1-4. Structural studies show that the protonated heterocyclic rings in these complexes create a hydrogen bond based cavity adjacent to the metal ion. Importantly, binding studies confirm that the substrates are bound within the complex cavity closer to the Lewis acidic metal in all complexes including the oxidation-sensitive Mn ion in complex 5. All complexes have been utilized as the reusable and heterogeneous catalysts for ring-opening reactions of assorted epoxides, cyanation reactions of various aldehydes, and epoxidation reactions of several olefins. This journal is
- Bansal, Deepak,Kumar, Gulshan,Hundal, Geeta,Gupta, Rajeev
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p. 14865 - 14875
(2015/02/19)
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- A novel P450-based biocatalyst for the selective production of chiral 2-alkanols
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A P450 monooxygenase from Nocardia farcinica (CYP154A8) catalyses the stereo- and regioselective hydroxylation of n-alkanes, still a challenging task in chemical catalysis. In a biphasic reaction system, the regioselectivity for the C2-position of C7-C9 alkanes was over 90%. The enzyme showed strict S-selectivity for all tested substrates, with enantiomeric excess (ee) of up to 91%. This journal is the Partner Organisations 2014.
- Von Bühler, Clemens J.,Urlacher, Vlada B.
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supporting information
p. 4089 - 4091
(2014/04/03)
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- A new gold-catalysed azidation of allenes
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A new gold-catalysed azidation reaction of allenes is presented as a new highly modular approach for the synthesis of substituted allyl derivatives containing nitrogen from simple precursors. This journal is The Royal Society of Chemistry.
- Hurtado-Rodrigo, Cesar,Hoehne, Stefanie,Munoz, Maria Paz
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supporting information
p. 1494 - 1496
(2014/02/14)
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- HYDROCARBON SYNTHESIS METHODS, APPARATUS, AND SYSTEMS
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Embodiments of the invention include apparatus and systems for hydrocarbon synthesis and methods regarding the same. In an embodiment, the invention includes a process for creating a hydrocarbon product stream comprising reacting a reaction mixture in the presence of a catalyst inside of a reaction vessel to form a product mixture, the reaction mixture comprising a carbon source and water. The temperature inside the reaction vessel can be between 450 degrees Celsius and 600 degrees Celsius and the pressure inside the reaction vessel can be above supercritical pressure for water. In an embodiment, the invention includes an extrusion reactor system for creating a hydrocarbon product stream. The temperature inside the extrusion reactor housing between 450 degrees Celsius and 600 degrees Celsius. Pressure inside the reaction vessel can be above supercritical pressure for water. Other embodiments are also included herein.
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Page/Page column 32
(2014/01/18)
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- Palladium on charcoal as a catalyst for stoichiometric chemo- and stereoselective hydrosilylations and hydrogenations with triethylsilane
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Stoichiometric quantities of triethylsilane in the presence of activated Pd/C as the catalyst can be used to effect chemo-, regio-, and stereoselective hydrosilylation and transfer hydrogenation reactions. α,β-Unsaturated aldehydes and ketones are selectively hydrosilylated to give the corresponding enol silanes or transfer hydrogenated to give the saturated carbonyl compounds in the presence of other reducible functional groups.
- Tuokko, Sakari,Pihko, Petri M.
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p. 1740 - 1751
(2015/02/19)
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- A Lewis acid catalytic core sandwiched by inorganic polyoxoanion caps: Selective H2O2-based oxidations with [Al III4(H2O)10(β-XW 9O33H)2]6- (X = AsIII, SbIII)
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The AlIII-containing polyanions [AlIII 4(H2O)10(β-XW9O 33H)2]4- with X = AsIII (1) and SbIII (2) feature four aluminum(iii) centers sandwiched by two trivacant (β-XW9O33) Keggin units, and trigger peroxide catalysis as well as substrate coordination via multiple Lewis acid site interactions.
- Carraro, Mauro,Bassil, Bassem S.,Soraru, Antonio,Berardi, Serena,Suchopar, Andreas,Kortz, Ulrich,Bonchio, Marcella
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supporting information
p. 7914 - 7916
(2013/09/02)
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- Yarrowia lipolytica dehydrogenase/reductase: An enzyme tolerant for lipophilic compounds and carbohydrate substrates
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Yarrowia lipolytica short chain dehydrogenase/reductase (YlSDR) was expressed in Escherichia coli, purified and characterized in vitro. The substrate scope for YlSDR mediated oxidation was investigated with alcohols and unprotected carbohydrates spectrophotometrically, revealing a preference for secondary compared to primary alcohols. In reduction direction, YlSDR was highly active on ribulose and fructose, suggesting that the enzyme is a mannitol-2-dehydrogenase. In order to explore substrate tolerance especially for space-demanding, lipophilic protecting groups, 5-O-trityl-d-ribitol and 5-O-trityl-α,β-d-ribose were investigated as substrates: YlSDR oxidized 5-O-trityl-d-ribitol and 5-O-trityl-α,β-d-ribose and reduced the latter at the expense of NADP(H).
- Napora, Kamila,Wrodnigg, Tanja M.,Kosmus, Patrick,Thonhofer, Martin,Robins, Karen,Winkler, Margit
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p. 3393 - 3395
(2013/06/27)
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- Highly selective Wacker oxidation of terminal olefins using magnetically recyclable Pd-Fe3O4 heterodimer nanocrystals
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A new highly selective and environment-friendly Wacker oxidation process employing superparamagnetic Pd-Fe3O4 heterodimer nanocrystals in EtOH-H2O under 1 atm O2 has been developed. Consistently high yields of the desired Wacker product and excellent reaction selectivity were observed in almost all of the reactions examined. This operationally simple oxidation protocol allows recycling of the Pd-Fe 3O4 catalyst after the reaction through the use of an external magnet. The Royal Society of Chemistry 2013.
- Byun, Sangmoon,Chung, Jooyoung,Jang, Youngjin,Kwon, Jungmin,Hyeon, Taeghwan,Kim, B. Moon
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p. 16296 - 16299
(2013/09/23)
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- Photocatalytic synthesis of oxygenated hydrocarbons from diesel fuel for mobile deNOx application
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Photocatalytic partial oxidation of dodecane has been studied as a model reaction of diesel fuel conversion to oxygenated hydrocarbons (OHCs) as an effective nitrogen oxide (NOx) reductant in selective catalytic reduction (SCR) systems. Thus, TiO2-based photocatalysts produced OHCs composed mainly of C1-C6 aldehydes under UV irradiation, and TiO2-SiO2 mixed oxide photocatalysts showed higher selectivity and yield to OHCs than pristine TiO2 by diluting contiguous Ti sites and suppressing complete oxidation to CO2. The effects of reaction variables were studied in detail. A novel scheme of NOx after-treatment system for diesel engine exhaust line was proposed involving the new photocatalytic reaction, where on-board photocatalytic partial oxidation of a small amount of diesel fuel produced OHCs that were supplied to the deNOx system as NOx reductant. Although further improvement is needed in the selectivity for OHCs as well as the system operability, the proposed scheme could be a more environment-friendly option than the reduction by urea, currently considered the most promising technology.
- Kim, Jae Yul,Kim, Yeon Ho,Han, Suenghoon,Choi, Sun Hee,Lee, Jae Sung
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- Palladium-catalyzed diorganozinc conjugate additions to enones: Preparative and computational studies
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The Pd-catalyzed conjugate addition of diorganozinc reagents to α,β-unsaturated carbonyl compounds has been applied to a variety of enone substrates, both cyclic and acyclic, encompassing various combinations of aryl and alkyl substitution, in combination with diorganozinc reagents incorporating alkyl (Me, linear and branched) or Ph groups. While both Pd 0 and PdII complexes have been found to be competent precatalysts, reaction yields are strongly dependent on the relative amounts of Pd to phosphane ligand. Thus, a 1:1 Pd/P ratio is well tolerated, but going to Pd/P = 1:2 leads to poor conversions and yields. A calculated Pd 0-mediated pathway involving an unusual oxidative addition step with simultaneous transmetalation, followed by reductive elimination, has been found to be compatible with the observed phosphane effect. A phosphane dependence is found in the Pd0-catalyzed diorganozinc conjugate addition to enones, which is compatible with a calculated reaction pathway proceeding through simultaneous oxidative addition/transmetalation followed by reductive elimination. Copyright
- Lorenzo, Paula,Aurrecoechea, Jose M.,De Lera, Angel R.,Alvarez, Rosana
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p. 2621 - 2626
(2013/06/04)
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- Simple and clean synthesis of ketones from internal olefins using PdCl 2/N,N-dimethylacetamide catalyst system
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A simple catalytic system consisting of PdCl2 and N,N-dimethylacetamide enabled clean and selective synthesis of ketones from internal olefins using molecular oxygen. Various functionalized internal olefins were directly and regioselectively oxidized; C atoms of CC bonds far from substituted moieties were preferably oxidized.
- Mitsudome, Takato,Yoshida, Syuhei,Tsubomoto, Yamato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information
p. 1596 - 1598
(2013/03/14)
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- Copper hydride-catalyzed reduction of electron-deficient olefins
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Copper hydride derived from CuF(PPh3)3·2MeOH- bis[(2-diphenylphosphino)phenyl] ethersilane can reduce electron-deficient olefins selectively and efficiently.
- Zheng, Ai-Jun,Shan, Feng-Jun,Li, Zheng-Ning,Li, Zeng-Chang,Jiang, Lan
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p. 1271 - 1276
(2013/07/19)
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- Palladium on graphene: The in situ generation of a catalyst for the chemoselective reduction of α,β-unsaturated carbonyl compounds
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Palladium-supported graphene oxide has been successfully applied as a catalyst precursor for the selective reduction of α,β-unsaturated carbonyl compounds. Pd nanoparticles were formed during the course of the reduction with only negligible leaching of the Pd species into the reaction mixture.
- Morimoto, Naoki,Yamamoto, Shun-Ichi,Takeuchi, Yasuo,Nishina, Yuta
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p. 15608 - 15612
(2013/09/12)
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- Chemoselective transfer hydrogenation of α,β-unsaturated ketones catalyzed by pincer-Pd complexes using alcohol as a hydrogen source
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A pincer-Pd complex was utilized in the chemoselective transfer hydrogenation of α,β-unsaturated ketones using n-BuOH as a hydrogen source and solvent. Good to excellent yields were obtained for various substrates even with reducible groups. Based on deuterium-labeling experiments, the reaction mechanism is proposed to occur via a pincer-Pd-hydride intermediate.
- Ding, Boqiang,Zhang, Zhenfeng,Liu, Yangang,Sugiya, Masashi,Imamoto, Tsuneo,Zhang, Wanbin
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supporting information
p. 3690 - 3693
(2013/08/23)
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- Solvent-free hydration of alkynes over a heterogeneous silver exchanged silicotungstic acid catalyst
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Silver exchanged silicotungstic acid (AgSTA) catalysts were prepared and characterized by X-ray diffraction, FT-IR spectroscopy, laser Raman, temperature programmed desorption of ammonia, FT-IR pyridine adsorption and X-ray photo electron spectroscopy. The activity of the catalysts was evaluated for the hydration of non-activated alkynes to corresponding carbonyl compounds without addition of any acid co-catalyst under solvent-free conditions. The highest catalytic activity was obtained for the catalyst with partially silver exchanged STA. This catalytic system provides one of the most straight forward syntheses of carbonyl compounds from terminal alkynes with Markovnikov-type regioselectivity. The catalyst can be recovered by simple filtration and is reusable without loss of activity and selectivity. A plausible reaction mechanism for the AgSTA catalyzed hydration of alkynes is proposed.
- Venkateswara Rao,Sai Prasad,Lingaiah
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experimental part
p. 1507 - 1514
(2012/06/01)
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- Efficient synthesis of carbonyl compounds: Oxidation of azides and alcohols catalyzed by vanadium pentoxide in water using tert-butylhydroperoxide
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Catalytic amount of vanadium reagent with tert-butylhydroperoxide as the oxidant was found to be an excellent oxidizing agent in aqueous medium. Vanadium pentoxide with aq tert-butylhydroperoxide readily oxidizes primary benzylic azides to the corresponding acids and secondary benzylic azides to the corresponding ketones in excellent yields. Further, vanadium pentoxide and aq tert-butylhydroperoxide combination turned out to be an effective catalyst for the oxidation of alcohols. Using vanadium pentoxide and aq tert- butylhydroperoxide primary alcohols were oxidized to the corresponding acids, whereas secondary alcohols underwent a smooth transformation to furnish corresponding ketones in excellent yields. All the oxidations are performed in water.
- Alagiri, Kaliyamoorthy,Prabhu, Kandikere Ramaiah
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scheme or table
p. 8544 - 8551
(2011/11/13)
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- Microwave promoted regeneration of carbonyl compounds from oximes using N, N-dichloro poly(styrene-co-divinylbenzene)sulphonamide resin
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An efficient, economically viable and operationally simple method was developed for deoximation of oximes (of ketones and aldehydes) to their corresponding carbonyl compounds using polymer beads of N, N-dichloro poly(styrene-co-divinylbenzene)sulphonamide resin. Polymeric reagent offered speedy conversion and substantial yields of products under mild condition and is recyclable. Deoximation was monitored by the use of 13C NMR.
- Beldar,Sharma, Mamta
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experimental part
p. 288 - 292
(2012/02/01)
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- Enzymatic racemization of amines catalyzed by enantiocomplementary ω-Transaminases
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A strategy for the biocatalytic racemization of primary α-chiral amines was developed by employing a pair of stereocomplementary PLP-dependent ω-transaminases. The interconversion of amine enantiomers proceeded through reversible transamination by a prochiral ketone intermediate, either catalyzed by a pair of stereocomplementary ω-transaminases or by a single enzyme possessing low stereoselectivity. To tune the system, the type and concentration of a nonchiral amino acceptor proved to be crucial. Finally, racemization could be achieved by the cross-transamination of two different amines without a requirement for an external amino acceptor. Several synthetically and industrially important amines could be enzymatically racemized under mild reaction conditions. ω-Transaminases play ping-pong: A biocatalytic protocol for the 'clean' racemization of α-chiral prim-amines was developed by an equilibrium-controlled deamination/amination sequence catalyzed by a pair of (R)- and (S)-ω-transaminases (see scheme).
- Koszelewski, Dominik,Grischek, Barbara,Glueck, Silvia M.,Kroutil, Wolfgang,Faber, Kurt
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experimental part
p. 378 - 383
(2011/03/21)
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- Stereoselective hydrosilylation of enals and enones catalysed by palladium nanoparticles
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A highly versatile and efficient hydrosilylation method by palladium nanoparticle catalysis allows the direct and chemoselective synthesis of 1)enolsilanes of high isomeric purity, 2)saturated aldehydes or ketones, or 3)the corresponding saturated acetals from α,β-unsaturated aldehydes or ketones. The choice of the product is determined by simply switching the solvent from THF to mixtures of THF/water or THF/alcohol. Copyright
- Benohoud, Meryem,Tuokko, Sakari,Pihko, Petri M.
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supporting information; experimental part
p. 8404 - 8413
(2011/08/07)
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- Catalytic oxidative cleavage of olefins by RuO4 organic solvent-free under ultrasonic irradiation
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All the works reported about oxidative cleavage of olefins by the RuCl3/NaIO4 catalytic system have been performed in biphasic water/organic solvent(s). The first organic solvent-free oxidation of C{double bond, long}C double bond by 2% RuCl3/4.1 equiv NaIO4/H2O is described here using both the emulsifier Aliquat 336 and 20 kHz ultrasonic irradiation.
- Rup, Sandrine,Sindt, Michèle,Oget, Nicolas
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scheme or table
p. 3123 - 3126
(2010/08/07)
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- Aerobic oxidation of primary aliphatic alcohols to aldehydes catalyzed by a palladium(II) polyoxometalate catalyst
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A hexadecyltrimethylammonium salt of a "sandwich" type polyoxometalate has been used as a ligand to attach a palladium(II) center. This Pd-POM compound was an active catalyst for the fast aerobic oxidation of alcohols. The unique property of this catalyst is its significant preference for the oxidation of primary versus secondary aliphatic alcohols. Since no kinetic isotope effect was observed for the dehydrogenation step, this may be the result of the intrinsically higher probability for oxidation of primary alcohols attenuated by steric factors as borne out by the higher reactivity of 1-octanol versus 2-ethyl-1-hexanol. The reaction is highly selective to aldehyde with little formation of carboxylic acid; autooxidation is inhibited. No base is required to activate the alcohol. The fast reactions appear to be related to the electron-acceptor nature of the polyoxometalate ligand that may also facilitate alcohol dehydrogenation in the absence of base.
- Barats, Delina,Neumann, Ronny
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scheme or table
p. 293 - 298
(2010/04/28)
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- Hydrogen bonding between solutes in solvents octan-1-ol and water
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The 1:1 equilibrium constants, K, for the association of hydrogen bond bases and hydrogen bond acids have been determined by using octan-1-ol solvent at 298 K for 30 acid-base combinations. The values of K are much smaller than those found for aprotic, rather nonpolar solvents. It is shown that the log K values can satisfactorily be correlated against αH 2?βH2, where αH 2 and βH2 are the 1:1 hydrogen bond acidities and basicities of solutes. The slope of the plot, 2.938, is much smaller than those for log K values in the nonpolar organic solvents previously studied. An analysis of literature data on 1:1 hydrogen bonding in water yields a negative slope for a plot of log K against αH 2?βH2, thus showing how the use of very strong hydrogen bond acids and bases does not lead to larger values of log K for 1:1 hydrogen bonding in water. It is suggested that for simple 1:1 association between monofunctional solutes in water, log K cannot be larger than about -0.1 log units. Descriptors have been obtained for the complex between 2,2,2-trifluoroethanol and propanone, and used to analyze solvent effects on the two reactants, the complex, and the complexation constant.
- Abraham, Michael H.,Gola, Joelle M. R.,Cometto-Muniz, J. Enrique,Acree, William E.
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experimental part
p. 7651 - 7658
(2011/02/25)
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- Highly efficient methyl ketone synthesis with photoactivated acetone and olefins assisted by Mg(II)-exchanged zeolite y
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(Figure Presented) We previously found that photoirradiation of an acetone/water mixture containing olefins affords the corresponding methyl ketones highly efficiently and selectively via a water-assisted C-C coupling between the acetonyl radical and olefins (Org. Lett. 2008, 10, 3117-3120). The reaction proceeds at room temperature without any additives and has a potential to be a powerful method for methyl ketone synthesis. Here we report that an addition of Mg2+-exchanged zeolite Y (MgY) to the above photoreaction system accelerates the methyl ketone formation, while maintaining high selectivity. Ab initio molecular orbital calculation reveals that the accelerated methyl ketone formation is due to the electrostatic interaction between Mg2+ and excited-state acetone. This leads to a charge polarization of the carbonyl moiety of excited-state acetone and accelerates the hydrogen abstraction from ground-state acetone (acetonyl radical formation). This promotes efficient addition of the acetonyl radical to olefins, resulting in methyl ketone formation enhancement. Adsorption experiments reveal that accumulation of olefins inside the zeolite pore also affects efficient radical addition to olefins. The present process successfully produces various methyl ketones with very high yield, and the MgY recovered can be reused for further reaction without loss of activity.
- Tsukamoto, Daijiro,Shiraishi, Yasuhiro,Hirai, Takayuki
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supporting information; experimental part
p. 1450 - 1457
(2010/05/19)
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