- Liquid-phase heterogeneous oxidation of hydroxypivalaldehyde with oxygen in alkaline aqueous solution in the presence of supported palladium catalyst
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The kinetics of a model reaction of hydroxypivalaldehyde oxidation with molecular oxygen in alkaline aqueous solution in the presence of 4% Pd/Al 2O3 was studied with the aim of searching for promising heterogeneous catalysts for D-g
- Zhizhkun,Chernaya,Trusov
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- Pivalic Acid as Combined Buffer and Scavenger for Studies of Cloud Water Chemistry with Pulse Radiolysis
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The reactions of cloud water with transition-metal ions may be studied using pivalic acid as buffer and OH(1.) scavenger.Commonly used phosphate buffers form strong complexes that may have an important effect on reaction kinetics.Low solubility products limit transition-metal ion concentrations to very low levels (micromolar).With pivalic acid as buffer, we can increase the Cu(II) concentration typically by a factor of 340.At the same time better buffer characteristics and less complex formation is achieved.The scavenger efficiency equals that of tert-butyl alcohol.The rate data and the spectra of pivalic acid radicals have been measured in N2O-saturated solutions of pivalic acid.The acid constant was found to be 4.9 +/- 0.1.The rate constants for the reaction of OH(1.) with pivalic acid have been re-evaluated: k = (7+/-2)E8 dm3 mol-1 s-1 and k = 6.5E8 dm3 mol-1 s-1.The importance of including reactions like H(1.) + (1.)CH2(CH3)2CCO2H in the reaction model is shown.The rate constants for the recombination of pivalic acid radicals are: k = (7+/-1)E8 dm3 mol-1 s-1, k = (7+/-3)E8 dm3 mol-1 s-1 and k = (3.7+/-0.4)E8 dm3 mol-1 s-1.
- Nauser, Thomas,Buehler, Rolf E.
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- Pd(II)-Catalyzed Chemoselective Acetoxylation of C(sp2)-H and C(sp3)-H Bonds in Tertiary Amides
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Palladium-catalyzed chemoselective C(sp2)-H and C(sp3)-H acetoxylation of synthetically useful tertiary amides is reported under relatively mild reaction conditions. This protocol proceeds through the assistance of a weakly coordinated directing group (Ca? O) and requires low catalyst (1.0 mol %) loading. Diverse functionalities, such as C(sp2)-Cl, C(sp3)-Cl,-CF3,-COOEt, and-NO2 groups, including morpholinyl, piperazinyl, and pyrrolidinyl heterocycles, are compatible under the reaction conditions. Further functionalization of this protocol is demonstrated by hydrolysis to alcohols, alcohol-acids, as well as reduction to tertiary amines. A preliminary kinetic isotope effect study supported the rate-limiting C-H bond activation process.
- Vijaykumar, Muniyappa,Punji, Benudhar
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- Chemoenzymatic Production of Enantiocomplementary 2-Substituted 3-Hydroxycarboxylic Acids from l-α-Amino Acids
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A two-enzyme cascade reaction plus in situ oxidative decarboxylation for the transformation of readily available canonical and non-canonical l-α-amino acids into 2-substituted 3-hydroxycarboxylic acid derivatives is described. The biocatalytic cascade consisted of an oxidative deamination of l-α-amino acids by an l-α-amino acid deaminase from Cosenzaea myxofaciens, rendering 2-oxoacid intermediates, with an ensuing aldol addition reaction to formaldehyde, catalyzed by metal-dependent (R)- or (S)-selective carboligases namely 2-oxo-3-deoxy-l-rhamnonate aldolase (YfaU) and ketopantoate hydroxymethyltransferase (KPHMT), respectively, furnishing 3-substituted 4-hydroxy-2-oxoacids. The overall substrate conversion was optimized by balancing biocatalyst loading and amino acid and formaldehyde concentrations, yielding 36–98% aldol adduct formation and 91–98% ee for each enantiomer. Subsequent in situ follow-up chemistry via hydrogen peroxide-driven oxidative decarboxylation afforded the corresponding 2-substituted 3-hydroxycarboxylic acid derivatives. (Figure presented.).
- Pickl, Mathias,Marín-Valls, Roser,Joglar, Jesús,Bujons, Jordi,Clapés, Pere
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p. 2866 - 2876
(2021/04/14)
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- Design and Synthesis of Novel N-(2-aminophenyl)benzamide Derivatives as Histone Deacetylase Inhibitors and Their Antitumor Activity Study
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Histone deacetylases (HDACs) are promising therapeutic targets for cancer therapy because inhibition of HDACs triggers growth arrest or apoptosis of tumor cells. In the present study, a new series of fluorinated N-(2-aminophenyl)benzamide derivatives were synthesized to investigate potential inhibition of HDACs and associated anticancer activity. Among the synthesized derivatives, compound 24a showed potent inhibitory activity of HDACs and higher antitumor efficacy in human cancer cell lines (HCT-116, MCF-7, and A549) compared with SAHA. Moreover, animal studies demonstrated that compound 24a showed potent in vivo antitumor efficacy in an HCT-116 colon cancer xenograft mouse model.
- La, Minh Thanh,Jeong, Byung-Hoon,Kim, Hee-Kwon
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supporting information
p. 740 - 743
(2021/03/16)
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- Aerobic Aliphatic Hydroxylation Reactions by Copper Complexes: A Simple Clip-and-Cleave Concept
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A simple imine clip-and-cleave concept has been developed for the selective hydroxylation of non-activated CH bonds in aliphatic aldehydes with dioxygen through a copper complex. The synthetic protocol involves reaction of a substrate aldehyde with N,N-diethyl-ethylendiamine to give the corresponding imine, which is used as a bidentate donor ligand forming a copper(I) complex with [Cu(CH3CN)4][CF3SO3]. After exposure of the reaction mixture to dioxygen acidic cleavage and aqueous workup liberates the corresponding β-hydroxylated aldehyde. The concept for the hydroxylation of trimethylacetaldehyde as well as adamantane and diamantane 1-carbaldehydes was investigated and the corresponding β-hydroxy aldehydes were obtained with high selectivities. The results of low temperature stopped-flow measurements indicate the formation of a bis(μ-oxido)dicopper complex as reactive intermediate. According to density functional theory (DFT, RI-BLYP-D3/def2-TZVP(SDD)/ COSMO(CH2Cl2)//RI-PBE-D3/def2-TZVP(SDD)) computations CH bonds suitably predisposed to the [Cu2O2]2+ core undergo hydroxylation in a concerted step with particularly low activation barriers, which explains the experimentally observed regioselectivities.
- Becker, Jonathan,Zhyhadlo, Yevheniia Y.,Butova, Ekaterina D.,Fokin, Andrey A.,Schreiner, Peter R.,F?rster, Moritz,Holthausen, Max C.,Specht, Pascal,Schindler, Siegfried
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p. 15543 - 15549
(2018/09/21)
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- Preparation method of hydroxypivalic acid
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The invention provides a preparation method of hydroxypivalic acid. The preparation method comprises the following steps: (1) adding a sodium carbonate water solution into a sodium polystyrenesulfonate water solution, stirring, regulating the pH value, adding a barium chloride water solution, stirring, standing, taking out, filtering, washing, and drying to obtain barium carbonate microspheres; (2) adding the barium carbonate microspheres into absolute ethyl alcohol, carrying out ultrasonic dispersion, adding CTAB, continuing to carry out ultrasonic dispersion to obtain a barium carbonate microsphere solution, dropwise adding a hydrated silica solution, carrying out magnetic stirring, standing, carrying out centrifuging, washing, drying, and calcining so as to obtain a BaO/SiO2 core-shell microsphere catalyst; (3) adding a formaldehyde water solution and triethylamine into a four-mouth flask, heating in a water bath, dropwise adding isobutyraldehyde, and carrying out reduced pressure distillation on a reaction liquid, so as to obtain hydroxyl pivaldehyde; and (4) adding hydroxyl pivaldehyde and a sodium hydroxide solution into the four-mouth flask, carrying out heating reflux, adding water and a catalyst, heating while stirring, carrying out suction filtration on the reaction liquid, concentrating a filtrate, regulating the pH value, carrying out extraction, and standing until crystals are separated. The preparation method has the beneficial effects of relatively high benefit, relatively low cost and mild condition.
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Paragraph 0052; 0053; 0057
(2017/01/02)
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- Method for preparing hydroxypivalic acid by catalytic oxidation of phosphotungstic acid
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The invention discloses a method for preparing hydroxypivalic acid by catalytic oxidation of phosphotungstic acid and belongs to the technical field of chemical industry.The method comprises: subjecting isobutyraldehyde and formaldehyde to aldol condensation under the catalytic action of triethylamine; in an existing production method of hydroxypivalic acid, the shortest oxidation time takes 9 hours; the process used herein takes only 4 hours to produce a product; in the existing production method of hydroxypivalic acid, highest product yield is about 75%, and the yield of the product of the invention is up to 80-85%.The defects that an original process produces many byproducts and the byproducts are difficult to separate are overcome, product purity is effectively improved, and the technical process is simplified; a catalyst used herein is reusable, the activity of the catalyst decreases at low speed, energy consumption of the oxidation process is low, and production cost is thus reduced.
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Paragraph 0042; 0043
(2016/12/01)
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- Synthesis method of 2,2-dimethyl-3-hydroxypropionic acid
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The invention discloses a synthesis method of 2,2-dimethyl-3-hydroxypropionic acid. With isobutyraldehyde and formaldehyde as the raw materials, 2,2-dimethyl-3-hydroxypropionic acid is directly prepared through aldol reaction and disproportionation and oxidation reaction, a catalyst composed of aluminium oxide and manganese oxide is added in the aldol reaction, and a catalyst formed by mixing bismuth oxide with aluminium oxide is added in the disproportionation and oxidation reaction; meanwhile, the reaction conditions are optimized, the excessive consumption of sodium hydroxide is lowered, reaction time is shortened, reaction energy consumption is lowered, reaction yield is improved, and high economic benefits are achieved.
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Paragraph 0030; 0031; 0034; 0035
(2017/03/14)
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- Gold(I)/copper(II)-cocatalyzed tandem cyclization/semipinacol reaction: Construction of 6-Aza/Oxa-Spiro[4.5]decane skeletons and formal synthesis of (±)-halichlorine
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A simple and efficient strategy for the construction of 6-aza/oxa-spiro[4.5]decane skeletons under the cocatalysis of gold(I)/copper(II) was developed, and its potential utility was demonstrated by a formal synthesis of the biologically active marine alkaloid (±)-halichlorine.
- Zhu, Dao-Yong,Zhang, Zhen,Mou, Xue-Qing,Tu, Yong-Qiang,Zhang, Fu-Min,Peng, Jin-Bao,Wang, Shao-Hua,Zhang, Shu-Yu
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p. 747 - 752
(2015/03/18)
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- Synthesis of the spiroacetal core of the cephalosporolide family of natural products
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The synthesis of four possible stereoisomers of the spiroacetal core of the natural products cephalosporolides H and I and penisporolides A and B is described. The key steps involve the use of Sharpless asymmetric dihydroxylation to install the desired stereochemistry of the γ-lactone ring and an oxidative radical cyclisation to form the spiroacetal ring system.
- Finch, Orla C.,Furkert, Daniel P.,Brimble, Margaret A.
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p. 590 - 596
(2014/02/14)
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- Solvent effect and reactivity trend in the aerobic oxidation of 1,3-propanediols over gold supported on titania: Nmr diffusion and relaxation studies
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In recent work, it was reported that changes in solvent composition, precisely the addition of water, significantly inhibits the catalytic activity of Au/TiO2 catalyst in the aerobic oxidation of 1,4-butanediol in methanol due to changes in diffusion and adsorption properties of the reactant. In order to understand whether the inhibition mechanism of water on diol oxidation in methanol is generally valid, the solvent effect on the aerobic catalytic oxidation of 1,3-propanediol and its two methyl-substituted homologues, 2-methyl-1,3-propanediol and 2,2-dimethyl-1,3-propanediol, over a Au/TiO2 catalyst has been studied here using conventional catalytic reaction monitoring in combination with pulsed-field gradient nuclear magnetic resonance (PFG-NMR) diffusion and NMR relaxation time measurements. Diol conversion is significantly lower when water is present in the initial diol/methanol mixture. A reactivity trend within the group of diols was also observed. Combined NMR diffusion and relaxation time measurements suggest that molecular diffusion and, in particular, the relative strength of diol adsorption, are important factors in determining the conversion. These results highlight NMR diffusion and relaxation techniques as novel, non-invasive characterisation tools for catalytic materials, which complement conventional reaction data. In solvent company: The solvent effect on the aerobic catalytic oxidation of 1,3-propanediol and its two methyl-substituted homologues, 2-methyl-1,3-propanediol and 2,2-dimethyl-1,3-propanediol, over a Au/TiO 2 catalyst has been studied. The results show that diol conversion is significantly lower when water is present in the initial diol/methanol mixture. A reactivity trend within the group of diols was also observed. Copyright
- D'Agostino, Carmine,Kotionova, Tatyana,Mitchell, Jonathan,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.,Gladden, Lynn F.,Mantle, Mick D.
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p. 11725 - 11732
(2013/09/12)
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- Oxidative esterification of homologous 1,3-propanediols
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The oxidative esterification of a homologous series of diols (1,3-propanediol,2-methyl-propanediol and 2,2-dimethyl-1,3-propanediol) with methanol has been investigated using titania-supported gold, palladium and gold-palladium catalysts using molecular oxygen. The gold-palladium catalysts showed the highest activity and 1,3-propanediol was the most reactive while the additional methyl groups decreased the reactivity. However, it is possible to achieve high selectivity to methyl 3-hydroxypropionate and 2-methyl-3- hydroxyisobutyrate by mono-oxidations. Graphical Abstract: [Figure not available: see fulltext.]
- Kotionova, Tatyana,Lee, Christopher,Miedziak, Peter J.,Dummer, Nicholas F.,Willock, David J.,Carley, Albert F.,Morgan, David J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
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p. 1114 - 1120
(2012/10/29)
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- Pd(II)-catalyzed primary-C(sp3)-H acyloxylation at room temperature
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With the aid of a novel S-methyl-S-2-pyridyl-sulfoximine (MPyS) directing group (DG), the unactivated primary β-C(sp3)-H bond of MPyS-N-amides oxidizes at room temperature. The catalytic conditions are applicable to the diacetoxylation of primary β,β′-C(sp 3)-H bonds, and the carboxylic acid solvent is pivotal in the formation of the C-O bond. The MPyS-DG cleaves from the oxidation products and is recovered. This method provides convenient access to α,α′- disubstituted-β-hydroxycarboxylic acids.
- Rit, Raja K.,Yadav, M. Ramu,Sahoo, Akhila K.
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supporting information; experimental part
p. 3724 - 3727
(2012/08/28)
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- Synthesis of quaternary carbon centers via hydroformylation
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The application of hydroformylation to the synthesis of quaternary carbon centers is reported. The synthesis of the highly substituted carbon is achieved by applying a catalytic amount of 1. Ligand 1 serves as a catalytic directing group by covalently and reversibly binding to both the substrate and catalyst. The intramolecular nature of the directing group strategy accelerates the hydroformylation reaction such that the reaction is performed at mild temperatures (35-55 °C) and with excellent regioselectivity (b:l > 94:6).
- Sun,Frimpong,Tan
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supporting information; experimental part
p. 11841 - 11843
(2010/11/04)
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- β2,2-aminoxy acids: A new building block for turns and helices
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The conformational properties of peptides 1-4 built from 3-aminoxy-2,2-dimethyl-propionic acid, a β2,2-aminoxy acid, were investigated by NMR spectroscopy and X-ray crystallography. A novel β N-O turn involving a nine-membered-ring intramolecular hydrogen bond between NHi+2 and COi was formed in diamides 1 and 2, which was further stabilized by another six-membered-ring intramolecular hydrogen bond between NHi+2 and NOi+1. Triamides 3 and 4 displayed a well-defined helical structure featuring two consecutive β N-O turns. The X-ray structure of 4 revealed that the amide carbonyl group at position i+2 was twisted +65.9° from that at i position, suggesting a novel 1.79 helix. Therefore, β2,2-aminoxy acid can be used as a new building block for turns and helices. Copyright
- Yang, Dan,Zhang, Yu-Hui,Zhu, Nian-Yong
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p. 9966 - 9967
(2007/10/03)
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- Herbicidal 3-isoxazolidinones and hydroxamic acids
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Novel 3-isoxazolidinone compounds and novel hydroxamic acid intermediates from which they are prepared exhibit herbicidal activity to grassy and broad-leaf plant species while leaving legumes, especially soybeans, unaffected. The preparation and herbicidal activity of the compounds is exemplified.
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