- Efficient Aerobic Oxidation of trans-2-Hexen-1-ol using the Aryl Alcohol Oxidase from Pleurotus eryngii
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The selective oxidation of trans-2-hexen-1-ol to the corresponding aldehyde using a recombinant aryl alcohol oxidase from Pleurotus eryngii (PeAAOx) is reported. Especially using the two liquid phase system to overcome solubility and product inhibition issues enabled to achieve more than 2.200.000 catalytic turnovers for the production enzyme as well as molar product concentrations, pointing towards an economic feasible reaction. (Figure presented.).
- de Almeida,van Schie,Ma,Tieves,Younes,Fernández-Fueyo,Arends,Riul,Hollmann
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- EFFICIENT INDIRECT ELECTROCHEMICAL IN SITU REGENERATION OF NAD+ AND NADP+ FOR ENZYMATIC OXIDATIONS USING IRON BIPYRIDINE AND PHENANTHROLINE COMPLEXES AS REDOX CATALYSTS
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Using iron bipyridine or phenanthroline complexes 1 as redox catalysts it was possible to electrochemically generate NAD(P)+ from NAD(P)H very efficiently.Electrochemically driven enzymatic oxidations of the test systems 2-hexen-1-ol and 2-butanol could be performed with 1e as redox catalyst in presence of yeast alcohol dehydogenase (YADH) or the alcohol dehydrogenase of thermoanaerobium brockii (TADH) with turnover numbers of about 40/h.
- Komoschinski, Joachim,Steckhan, Eberhard
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- Biocatalytic synthesis of the Green Note trans-2-hexenal in a continuous-flow microreactor
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The biocatalytic preparation of trans-hex-2-enal from trans-hex-2-enol using a novel aryl alcohol oxidase from Pleurotus eryngii (PeAAOx) is reported. As O2-dependent enzyme PeAAOx-dependent reactions are generally plagued by the poor solubility of O2 in aqueous media and mass transfer limitations resulting in poor reaction rates. These limitations were efficiently overcome by conducting the reaction in a flow-reactor setup reaching unpreceded catalytic activities for the enzyme in terms of turnover frequency (up to 38 s-1) and turnover numbers (more than 300000) pointing towards preparative usefulness of the proposed reaction scheme.
- Van Schie, Morten M.C.H.,De Almeida, Tiago Pedroso,Laudadio, Gabriele,Tieves, Florian,Fernández-Fueyo, Elena,No?l, Timothy,Arends, Isabel W.C.E.,Hollmann, Frank
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- Characterization of a new (Z)-3:(E)-2-hexenal isomerase from tea (Camellia sinensis) involved in the conversion of (Z)-3-hexenal to (E)-2-hexenal
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Two major green leaf volatiles (GLVs) in tea that contribute greatly to tea aroma, particularly the green odor, are (E)-2-hexenal and (Z)-3-hexenal. Until now, their formation and related mechanisms during tea manufacture have remained unclear. Our data showed that the contents of (E)-2-hexenal and (Z)-3-hexenal increased more than 1000-fold after live tea leaves were torn. Subsequently, a new (Z)-3:(E)-2-hexenal isomerase (CsHI) was identified in Camellia sinensis. CsHI irreversibly catalyzed the conversion of (Z)-3-hexenal to (E)-2-hexenal. Abiotic stresses including low temperature, dehydration, and mechanical wounding, did not influence the (E)-2-hexenal content in intact tea leaves during withering, but regulated the proportions of (Z)-3-hexenal and (E)-2-hexenal in torn leaves by modulating CsHI at the transcript level. For the first time, this work reveals the formation of (E)-2-hexenal during tea processing and suggests that CsHI may play a pivotal role in tea flavor development as well as in plant defense against abiotic stresses.
- Chen, Cong,Chen, Shuna,He, Puming,Li, Bo,Tu, Youying,Wang, Feiquan,Wang, Kaixi,Wen, Xinli,Wu, Yuanyuan,Yu, Fei,Zhang, Jianming
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- Synthesis and Biological Evaluation of Hoshionolactam-Based Compounds
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In search of novel antitrypanosomal agents based on hoshinolactam (IC50=3.9 nM), we disclose the synthesis and biological evaluations of 14 different analogues of the natural product using combinations of different acids and lactams. Antitrypanosomal activity assays revealed that the synthesized analogues were less potent than the parent natural product.
- Elizebath, Drishya,Jachak, Gorakhnath R.,Reddy, D. Srinivasa,Shanmugam, Dhanasekaran,Shukla, Anurag
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p. 2212 - 2218
(2021/07/22)
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- First synthesis of 3-S-glutathionylhexanal-d8 and its bisulfite adduct
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3-Sulfanylhexan-1-ol (3SH) is an impact odorant of white wines, imparting tropical fruit aromas. A reliable synthetic pathway to 3-S-glutathionylhexanal (glut-3SH-al), a precursor to 3SH that has not been intensively studied, was developed starting from 1-butanol. Application of this synthesis to 1-butanol-d10, conserved eight deuteriums, producing glut-3SH-al-d8, which can be used as an internal standard for future work on the occurrence and evolution of glut-3SH-al in wine systems. Additionally, both glut-3SH-SO3 and glut-3SH-SO3-d8 were synthesised from the corresponding aldehyde, enabling further study of the role of these bisulfite adducts in 3SH biogenesis.
- Muhl, Jennifer R.,Pilkington, Lisa I.,Deed, Rebecca C.
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supporting information
(2020/06/17)
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- Biosynthesis of Mycotoxin Fusaric Acid and Application of a PLP-Dependent Enzyme for Chemoenzymatic Synthesis of Substituted l -Pipecolic Acids
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Fusaric acid (FA) is a well-known mycotoxin that plays an important role in plant pathology. The biosynthetic gene cluster for FA has been identified, but the biosynthetic pathway remains unclarified. Here, we elucidated the biosynthesis of FA, which features a two-enzyme catalytic cascade, a pyridoxal 5′-phosphate (PLP)-dependent enzyme (Fub7), and a flavin mononucleotide (FMN)-dependent oxidase (Fub9) in synthesizing the picolinic acid scaffold. FA biosynthesis also involves an off-line collaboration between a highly reducing polyketide synthase (HRPKS, Fub1) and a nonribosomal peptide synthetase (NRPS)-like carboxylic acid reductase (Fub8) in making an aliphatic α,β-unsaturated aldehyde. By harnessing the stereoselective C-C bond-forming activity of Fub7, we established a chemoenzymatic route for stereoconvergent synthesis of a series of 5-alkyl-, 5,5-dialkyl-, and 5,5,6-trialkyl-l-pipecolic acids of high diastereomeric ratio.
- Hai, Yang,Chen, Mengbin,Huang, Arthur,Tang, Yi
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supporting information
p. 19668 - 19677
(2020/12/01)
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- Method for continuously synthesizing trans -2 - hexenal by micro-channel reactor (by machine translation)
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The invention belongs to the field, organic synthesis. The invention relates to a trans -2 - hexenal method. The method for preparing trans 4 - hexenal by continuous hydrolysis of -2 ethoxy 6 -1 dipropyl 3 -2 - dioxane (for short cyclization intermediate) through a micro-channel reactor is mainly solved by the preparation method. In the prior art, under the 10% presence of dilute acid (Unified), reflux distillation hydrolysis, oil-water layering, oil extraction, and a water layer backwater reactor are continuously distilled to the oil-free layer, and the water is undissolved. There is a long hydrolysis time, for example. Energy consumption is high, aftertreatment is tedious, serialization, hydrolysis yield and the like cannot be realized. By adopting the microchannel reactor, the 20 - 30% dilute acid concentration can be improved, the residence time is shortened, and continuous hydrolysis. The hydrolyzate is simple oil-water layering to obtain the crude product, and the hydrolyzed water layer can be recycled. The defects in the traditional hydrolytic distillation process, hydrolysis, long distillation time, complex process, and high energy consumption are overcome. , The process risk, and is suitable for industrial production. (by machine translation)
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Paragraph 0014; 0025; 0027; 0028-0047
(2019/08/01)
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- Catalytic performance of bulk and colloidal Co/Al layered double hydroxide with Au nanoparticles in aerobic olefin oxidation
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A Co/Al layered double hydroxide material was synthesized in both bulk and exfoliated (colloidal) forms. Anion exchange with methionine allowed immobilization of Au nanoparticles previously prepared by a biomimetic method using an anti-oxidant tea aqueous extract to reduce the Au salt solution. The catalytic performance of bulk and exfoliated clays Au-hybrid materials was assessed in aerobic olefin epoxidation. Both catalysts were very active towards the epoxide products and with very interesting substrate conversion levels after 80 h reaction time. The Au-exfoliated material, where the nanosheets work as large ligands, yielded higher product stereoselectivity in the case of limonene epoxidation. This arises from a confined environment around the Au nanoparticles wrapped by the clay nanosheets modulating access to the catalytic active centres by reagents. Mechanistic assessment was also accomplished for styrene oxidation by DFT methods.
- Leandro, Sónia R.,Fernandes, Cristina I.,Viana,Mourato,Vaz, Pedro D.,Nunes, Carla D.
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- Synthesis method of 2-hexenoic aldehyde
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The invention discloses a synthesis method of 2-hexenoic aldehyde. Raw materials n-butanal and alkyl alcohol react with each other under catalysis of a catalyst para-toluenesulfonic acid, the obtainedacetal and vinyl alkyl ether are subjected to an addition reaction under catalysis of boron trifluoride and B(C6F5)3 mixed solution, the obtained addition product is heated, boiled, hydrolyzed and distilled under the catalytic effect of a diluted acid aqueous solution, the obtained 2-hexenoic aldehyde crude product is subjected to continuous vacuum rectification, and high-purity 2-hexenoic aldehyde is obtained. The route provided by the invention reduces the consumption of the raw materials, the yield is considerable, and the product has the competitive advantage.
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Paragraph 0022-0029
(2019/01/14)
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- Method for synthesizing trans-2-hexenal
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The invention discloses a method for synthesizing trans-2-hexenal. The method includes steps of (1), adding acidic ionic liquid into reaction flasks, completely dropwise adding vinyl ethyl ether and butyraldehyde mixed liquid into the reaction flasks at the temperatures of 0-25 DEG C, then heating systems until the temperatures of the systems reach 20-45 DEG C, carrying out stirring reaction for 1-6 hours, and carrying out reduced pressure distillation after the reaction is completely carried out so as to obtain cyclization intermediates A; adding dilute sulfuric acid aqueous solution and theintermediates A into reaction flasks, erecting reflux oil and water layering devices, carrying out heating normal-pressure distillation for 4-48 hours, and extracting upper oil layers into oil layer receiving flasks; (3), rectifying and purifying hexenal crude products, carrying out normal-pressure rectification to obtain substances with low boiling points and then carrying out reduced pressure rectification to obtain the trans-2-hexenal. A molar ratio of butyraldehyde to vinyl ethyl ether is 2:1-5:1, and the usage of the acidic ionic liquid accounts for 0.1-5% of the total weight of the vinylethyl ether; the acidic ionic liquid is [(CH2)3SO3HMIM][HSO4] or [(CH2)3SO3HMIM][CF3SO3]. The oil layers are the hexenal crude products; the mass concentration of the dilute sulfuric acid aqueous solution is 0.5-25%, and a weight ratio of the dilute sulfuric acid aqueous solution to the intermediates A is 0.2:1-2:1. The method has the advantages of environmental protection, low cost and high yield.
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Paragraph 0025; 0027; 0031; 0035; 0039
(2018/11/22)
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- One-Pot l-Proline-Mediated Stereoselective α-C(sp2)–H Fluorination of α,β-Unsaturated Aldehydes through Methoxyfluorination–Elimination
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A one-pot, two-step l-proline-mediated stereoselective α-C(sp2)–H fluorination of α,β-unsaturated aldehydes towards their corresponding (Z)-α-fluoro-α,β-unsaturated aldehydes has been developed. The first step utilises Selectfluor as a fluorinating agent in CH3NO2/MeOH forming (Z)-α-fluoro-α,β-unsaturated aldehydes and their corresponding dimethyl acetals through methoxyfluorination-elimination. In the second step, water is added to promote the hydrolytic cleavage of the dimethyl acetals. The obtained (Z)-α-fluoro-α,β-unsaturated aldehydes were smoothly reduced to the corresponding alcohols by using NaBH4.
- Zhou, Jiadi,Jiang, Xinpeng,Jin, Can,Guo, Zhicheng,Su, Bin,Su, Weike
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supporting information
p. 3631 - 3634
(2017/07/22)
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- Characterization of the monolignol oxidoreductase AtBBE-like protein 15 L182V for biocatalytic applications
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Monolignol oxidoreductases from the berberine bridge enzyme-like (BBE-like) protein family (pfam 08031) catalyze the oxidation of monolignols to the corresponding aldehydes. In this report, we explore the potential of a monolignol oxidoreductase from Arabidopsis thaliana (AtBBE-like protein 15) as biocatalyst for oxidative reactions. For this study we employed a variant with enhanced reactivity towards oxygen, which was obtained by a single amino acid exchange (L182V). The pH and temperature optima of the purified AtBBE-like protein 15 L182V were determined as well as the tolerance toward organic co-solvents; furthermore the substrate scope was characterized. The enzyme has a temperature optimum of 50 °C and retains more than 50% activity between pH 5 and pH 10 within 5 min. The enzyme shows increased activity in the presence of various co-solvents (10–50% v/v), including acetonitrile, 2-propanol, 1,4-dioxane, and dimethyl sulfoxide. Primary benzylic and primary or secondary allylic alcohols were accepted as substrates. The enantioselectivity E in the oxidation of secondary alcohols was good to excellent (E>34 to?>200).
- Pils, Sabine,Schnabl, Kordula,Wallner, Silvia,Daniel, Bastian,Macheroux, Peter,Kljajic, Marko,Kupresanin, Nina,Breinbauer, Rolf,Fuchs, Michael,Rocha, Raquel,Schrittwieser, Joerg H.,Kroutil, Wolfgang
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- Total synthesis and biological evaluation of the tetramic acid based natural product harzianic acid and its stereoisomers
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The bioactive natural product harzianic acid was prepared for the first time in just six steps (longest linear sequence) with an overall yield of 22%. The identification of conditions to telescope amide bond formation and a Lacey-Dieckmann reaction into one pot proved important. The three stereoisomers of harzianic acid were also prepared, providing material for comparison of their biological activity. While all of the isomers promoted root growth, improved antifungal activity was unexpectedly associated with isomers in the enantiomeric series opposite that of harzianic acid.
- Healy, Alan R.,Vinale, Francesco,Lorito, Matteo,Westwood, Nicholas J.
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supporting information
p. 692 - 695
(2015/03/05)
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- Negatively Charged N-Heterocyclic Carbene-Stabilized Pd and Au Nanoparticles and Efficient Catalysis in Water
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Herein we describe the synthesis of negatively charged N-heterocyclic carbene (NHC)-functionalized palladium and gold nanoparticles (NPs), which are stable in water for over 3 months. The formation of these NHC-NPs proceeds via an efficient ligand exchange procedure. This method was successfully applied to different negatively charged NHCs bearing sulfonate and carboxylate groups. The obtained PdNPs were investigated as catalysts in hydrogenation reactions and showed high catalytic activity (TON up to 2500 and TOF up to 2000 h-1).
- Ferry, Angélique,Schaepe, Kira,Tegeder, Patricia,Richter, Christian,Chepiga, Kathryn M.,Ravoo, Bart Jan,Glorius, Frank
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p. 5414 - 5420
(2015/09/15)
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- Stable gold(III) catalysts by oxidative addition of a carbon-carbon bond
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Low-valent late transition-metal catalysis has become indispensable to chemical synthesis, but homogeneous high-valent transition-metal catalysis is underdeveloped, mainly owing to the reactivity of high-valent transition-metal complexes and the challenges associated with synthesizing them. Here we report a carbon-carbon bond cleavage at ambient conditions by a Au(i) complex that generates a stable Au(iii) cationic complex. In contrast to the well-established soft and carbophilic Au(i) catalyst, this Au(iii) complex exhibits hard, oxophilic Lewis acidity. For example, we observed catalytic activation of α,β-unsaturated aldehydes towards selective conjugate additions as well as activation of an unsaturated aldehyde-allene for a [2 + 2] cycloaddition reaction. The origin of the regioselectivity and catalytic activity was elucidated by X-ray crystallographic analysis of an isolated Au(iii)-activated cinnamaldehyde intermediate. The concepts revealed suggest a strategy for accessing high-valent transition-metal catalysis from readily available precursors.
- Wu, Chung-Yeh,Horibe, Takahiro,Jacobsen, Christian Borch,Toste, F. Dean
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p. 449 - 454
(2015/03/04)
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- METHOD FOR PRODUCING α,β-UNSATURATED CARBONYL COMPOUNDS
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PROBLEM TO BE SOLVED: To provide a simple and efficient, novel method for producing α,β-unsaturated carbonyl compounds, which can provide α,β-unsaturated carbonyl compounds from allyl alcohols with high yields under a mild reaction condition, and has extremely little influence and toxicity on the environment and the human body. SOLUTION: Provided is a method for producing α,β-unsaturated carbonyl compounds, the method comprising reacting allyl alcohols and hydrogen peroxide to carbonylate alcohol portions to produce corresponding α,β-unsaturated carbonyl compounds. As a reaction catalyst, there are used an Fe(II) or Fe(III) salt soluble in water or an organic solvent, and at least one picolinic acid selected from 2-picolinic acid and 6-C1-4 alkyl-2-picolinic acid in coexistence in a ratio of 1:1 to 1:4. COPYRIGHT: (C)2015,JPOandINPIT
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Paragraph 0037; 0042-0043
(2016/12/26)
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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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- Metal-organic framework encapsulated Pd nanoparticles: Towards advanced heterogeneous catalysts
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A novel synthesis strategy is developed to encapsulate palladium precursors through ligand design prior to MOF assembly, achieving uniformly distributed palladium NPs inside the cavities of MOFs. This strategy can avoid the different diffusion resistance between external and internal surfaces, and thus allow metal precursors to be easily deposited into the pores and evenly distributed within MOF networks. The embedded Pd NPs exhibited excellent shape-selectivity in olefin hydrogenation, as well as high catalytic efficiencies in aerobic oxidation of alcohols and reduction of nitrobenzene, showing significantly enhanced catalytic activity and stability as compared to those synthesized using a traditional impregnation method. The superior catalytic activity and stability came from the synergetic effects of nano-confinement and electron-donation offered by the MOF framework.
- Chen, Liyu,Chen, Huirong,Luque, Rafael,Li, Yingwei
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p. 3708 - 3714
(2014/11/07)
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- Oxidation of allylic and benzylic alcohols to aldehydes and carboxylic acids
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An oxidation of allylic and benzylic alcohols to the corresponding carboxylic acids is effected by merging a Cu-catalyzed oxidation using O 2 as a terminal oxidant with a subsequent chlorite oxidation (Lindgren oxidation). The protocol was optimized to obtain pure products without chromatography or crystallization. Interception at the aldehyde stage allowed for Z/E-isomerization, thus rendering the oxidation stereoconvergent with respect to the configuration of the starting material.
- K?nning, Daniel,Olbrisch, Tobias,Sypaseuth, Fanni D.,Tzschucke, C. Christoph,Christmann, Mathias
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supporting information
p. 5014 - 5016
(2014/05/06)
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- Palladium supported on an acidic metal-organic framework as an efficient catalyst in selective aerobic oxidation of alcohols
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Highly dispersed palladium nanoparticles were deposited on an acidic MOF (MIL-101) by using a simple colloidal method. The resulting Pd/MIL-101 catalyst was highly active in the liquid-phase aerobic oxidation of a wide range of alcohols including benzyl, allylic, aliphatic and heterocyclic alcohols as well as diols, affording the desired oxidation products in high yields under base-free and mild conditions. The catalyst was shown to be able to efficiently catalyze aerobic oxidation even at ambient temperature using air instead of pure O2. The solvent-free oxidation of benzyl alcohol gave a remarkably high turnover frequency (TOF) of approximately 16900 h-1. However, the catalytic activity was significantly suppressed when ethylenediamine was grafted on the uncoordinated Cr sites of the MIL-101 support, which suggests that the open Cr sites might play an important role in promoting the oxidation of alcohols in the present catalytic system.
- Chen, Gongzhou,Wu, Shijian,Liu, Hongli,Jiang, Huanfeng,Li, Yingwei
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p. 230 - 235
(2013/02/23)
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- Control of the selectivity in multi-functional group molecules using supported gold-palladium nanoparticles
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The oxidation of 2-hexen-1-ol and 1-hexen-3-ol with air has been studied using supported gold, palladium and gold-palladium catalysts. The main aim was to determine if either the alcohol or alkene functional group can be oxidised selectively. However, based on the reaction products observed (2-hexen-1-ol forms 2-hexene, hexanal, (E)-2-hexenal, (E)-3-hexen-1-ol, 4-hexen-1-ol and (E)-2-hexanoic acid. 1-Hexen-3-ol forms 1-hexene, 3-hexanone, 1-hexen-3-one and 3-hexenol), the main pathway in these reactions is isomerisation and, in addition, significant yields of the products are due to a disproportionation reaction. Controlling the selectivity in molecules with multiple function groups by manipulating the catalyst composition and reaction conditions can promote or hinder the various reaction pathways, thereby increasing the selectivity to the desired oxidation products.
- Alshammari, Hamed,Miedziak, Peter J.,Morgan, David J.,Knight, David W.,Hutchings, Graham J.
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p. 1244 - 1254
(2013/06/26)
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- One-pot oxidation/isomerization of Z-allylic alcohols with oxygen as stoichiometric oxidant
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A method for generating (E)-α,β-unsaturated aldehydes from Z-allylic alcohols or E/Z-mixtures is described. The one-pot procedure involves a Cu-catalyzed oxidation followed by an organocatalytic Z/E-isomerization with N,N-dimethylaminopyridine (DMAP).
- Koenning, Daniel,Hiller, Wolf,Christmann, Mathias
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supporting information
p. 5258 - 5261
(2013/01/15)
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- Titanium(IV)-promoted regioselective nucleophilic ring-opening reaction of chiral epoxyallyl alcohols with acids as a tool for ready access to chiral 1,2,3-triol monoesters: Application to stereoselective total synthesis of macrolides
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Titanium(IV)-promoted regioselective ring-opening reaction of chiral epoxy-allyl alcohols (Sharpless conditions as the key strategic step) is developed as a tool for ready access to chiral 5,6-dihydroxyoct-7-en-4-yl alkoxylates. Later, the synthetic utility of products thereof was demonstrated through the RCM based stereoselective synthesis of various natural products.
- Radha Krishna, Palakodety,Ramana, D. Venkata
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experimental part
p. 674 - 679
(2012/03/22)
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- OXIDATION OF PRIMARY ALIPHATIC ALCOHOLS WITH A NOBLE METAL POLYOXOMETALATE COMPLEX
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A process of oxidizing primary alcohols to their corresponding aldehydes is disclosed. The process is effected in the presence of noble metal polyoxometalate complexes. A novel process for preparing noble metal polyoxometalate complexes, and novel noble metal polyoxometalate complexes are also disclosed.
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Page/Page column 10-11
(2012/08/08)
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- Well-defined alkylpalladium complexes with pyridine-carboxylate ligands as catalysts for the aerobic oxidation of alcohols
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Neophylpalladium complexes of the type [Pd(CH2CMe 2Ph)(N-O)(L)], where N-O is picolinate or a related bidentate, monoanionic ligand (6-methylpyridine-2-carboxylate, quinoline-2-carboxylate, 2-pyridylacetate or pyridine-2-sulfonate) and L is pyridine or a pyridine derivative, efficiently catalyze the oxidation of a range of aliphatic, benzylic and allylic alcohols with oxygen, without requiring any additives. A versatile method is described which allows the synthesis of the above-mentioned complexes with a minimum synthetic effort from readily available materials. Comparison of the rates of oxidation of 1-phenylethanol with different catalysts reveals the influence of the structure of the bidentate N-O chelate and the monodentate ligand L on the catalytic performance of these complexes. The Royal Society of Chemistry 2012.
- Melero, Cristobal,Shishilov, Oleg N.,Alvarez, Eleuterio,Palma, Pilar,Campora, Juan
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p. 14087 - 14100
(2013/01/15)
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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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- Biooxidation of Primary Alcohols to Aldehydes through Hydrogen Transfer Employing Janibacter terrae
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Chemoselective oxidations still represent a challenge for chemists. Lyophilized cells of Janibacter terrae were employed for the chemoselective oxidation of primary alcohols to the corresponding aldehydes by hydrogen transfer with the use of acetaldehyde as the hydrogen acceptor. Secondary alcohol moieties were transformed at a much slower rate. The substrate spectrum encompasses substituted benzyl alcohols, whereby substrates with a substituent in the meta position were well tolerated, whereas only very small substituants were tolerated in the ortho position. Furthermore, nalkanols and allylic alcohols were transformed with good conversions. The biocatalyst was compatible with DMSO as a water miscible organic solvent up to 30 % v/v.
- Orbegozo, Thomas,De Vries, Johannes G.,Kroutil, Wolfgang
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experimental part
p. 3445 - 3448
(2010/09/05)
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- Binuclear complexes for aerobic oxidation of primary alcohols and carbohydrates
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The influence of electron-donating and electron-accepting properties of three pentadentate ligands was determined in connection with the aerobic oxidation ability of the corresponding binuclear copper(II) complexes for benzyl and allyl alcohols; additionally, the catalytic performance of their palladium and platinum analogs was characterized under comparable conditions. Quantitative aerobic oxidation of benzyl alcohol at 40 °C was achieved with a binuclear copper(II) complex - TEMPO catalyst in 2.5 h, while the regioselective aerobic oxidation of underivatized methyl-β-d-glucopyranoside was accomplished in about 35% yield at 60 °C after 24 h.
- Striegler, Susanne,Dunaway, Natasha A.,Gichinga, Moses G.,Milton, Lisa K.
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supporting information; experimental part
p. 7927 - 7932
(2010/11/03)
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- Copper(II)-coordinated organic nanotube: A novel heterogeneous catalyst for various oxidation reactions
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Copper(II)-coordinated organic nanotube can function as a heterogeneous catalyst for oxidation of a variety of organic compounds in the presence of hydrogen peroxide and tert-butyl hydroperoxide. The morphology of this catalyst remained same before and after the oxidation reactions. The catalyst can be reused for several times. In the presence of hydrogen peroxide, Copper(II)-coordinated organic nanotube formed a stable brown color peroxo bridge intermediate. But such intermediate did not form with tert-butyl hydroperoxide.
- Chattopadhyay, Tanmay,Kogiso, Masaki,Asakawa, Masumi,Shimizu, Toshimi,Aoyagi, Masaru
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experimental part
p. 9 - 13
(2011/02/25)
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- Catalytic activity dependency on catalyst components in aerobic copper-TEMPO oxidation
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The influence of catalyst components in the copper-TEMPO (2,2,6,6-tetramethylpiperidine N-oxide) catalysed aerobic oxidation of alcohols was investigated. The type and amount of base greatly influences reactivity. The bipyridyl ligand concentration had no major influence on catalysis, but ex-cessive amounts led to a decrease in activity for longer reaction times. The kinetic dependency for TEMPO was found to be 1.15, and for copper 2.25, which is an indication of a binuclear catalytic system. Optimised conditions with various allylic and aliphatic alcohols give good to excellent rapid oxidations.
- Kumpulainen, Esa T. T.,Koskinen, Ari M. P.
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experimental part
p. 10901 - 10911
(2010/04/05)
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- Selective oxidation of alcohols with hydrogen peroxide catalyzed by hexadentate binding 8-quinolinolato manganese(III) complexes
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A series of hexadentate 8-quinolinolato manganese(III) complexes were synthesized and proven to own a distorted octahedral geometry via elemental analysis, solid UV-vis spectroscopy and Hartree-Fock/3-21G+ calculation. These Mn(III) complexes were found to be more efficient than their corresponding tetradentate 8-quinolinolato manganese(II) and salen-MnIIIOAc for the oxidation of alcohols in acetone medium, being due to their special hexadentate binding structures that could open an axial Mn{single bond}O bond to form the more active pentadentate structures in the presence of aqueous hydrogen peroxide, as supported by UV-vis spectra. The halogen substituents in ligand's aryl ring could significantly enhance the catalytic activities and 5-chloro-7-iodo-8-quinolinolato manganese(III) gave the highest turnover number (TON). A reasonable mechanism for the present catalytic system was proposed.
- Ye, Zhengpei,Fu, Zaihui,Zhong, Sheng,Xie, Fang,Zhou, Xiaoping,Liu, Fenglan,Yin, Dulin
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experimental part
p. 110 - 115
(2009/04/13)
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- Oppenauer oxidation of secondary alcohols with 1,1,1-trifluoroacetone as hydride acceptor
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(Chemical Equation Presented) 1,1,1-Trifluoroacetone (2a) reacts as a hydride-acceptor in the Oppenauer oxidation of secondary alcohols (1) in the presence of diethylethoxyaluminum. The oxidant allows for selective oxidation of secondary alcohols in the presence of primary alcohols.
- Mello, Rossella,Martinez-Ferrer, Jaime,Asensio, Gregorio,Gonzalez-Nunez, Maria Elena
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p. 9376 - 9378
(2008/03/13)
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- Oxidation of allylic alcohols to α,β-unsaturated carbonyl compounds with aqueous hydrogen peroxide under organic solvent-free conditions
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Allylic alcohols are chemoselectively oxidized to α,β- unsaturated carbonyl compounds in high yield with aqueous H2O 2 in the presence of Pt black catalyst under organic solvent-free conditions. The catalyst is easily recyclable and effective for at least 7 cycles. The Royal Society of Chemistry.
- Kon, Yoshihiro,Usui, Yoko,Sato, Kazuhiko
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p. 4399 - 4400
(2008/04/01)
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- The direct preparation of functionalised cyclopropanes from allylic alcohols or α-hydroxyketones using tandem oxidation processes
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New manganese dioxide-mediated tandem oxidation processes (TOPs) have been developed, which facilitate the direct conversion of allylic alcohols and α-hydroxyketones into polysubstituted functionalised cyclopropanes. In the simplest version, the oxidation of an allylic alcohol is carried out in the presence of a stabilised sulfurane, and the intermediate α,β-unsaturated carbonyl compound undergoes in situ cyclopropanation. By using a combination of stabilised phosphorane and sulfurane, the direct conversion of allylic alcohols or α-hydroxyketones into functionalised cyclopropanes is achieved, with in situ cyclopropanation being followed by Wittig olefination, or vice versa. The application of these methods to a formal synthesis of the lignan (±)-picropodophyllone, and to novel analogues of the insecticide allethrin II, is described.
- McAllister, Graeme D.,Oswald, Magalie F.,Paxton, Richard J.,Raw, Steven A.,Taylor, Richard J.K.
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p. 6681 - 6694
(2007/10/03)
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- Oxidation of alcohols to carbonyl compounds with CrO3· SiO2 in supercritical carbon dioxide
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Supercritical carbon dioxide (scCO2) is an effective reaction medium to perform the oxidation of primary and secondary aliphatic alcohols to the corresponding carbonyl compounds with chromium trioxide supported on silica. These reactions were performed by flowing a solution of the alcohol in scCO2 through a column containing the supported reagent and recovering the product by depressurization. This method avoids the use of organic solvents and the contamination of the products with chromium species.
- Gonzalez-Nunez, Maria Elena,Mello, Rossella,Olmos, Andrea,Accrete, Rafael,Asensio, Gregorio
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p. 1039 - 1042
(2007/10/03)
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- Regioselective alkene carbon-carbon bond cleavage to aldehydes and chemoselective alcohol oxidation of allylic alcohols with hydrogen peroxide catalyzed by [cis-Ru(II)(dmp)2(H2O)2] 2+ (dmp = 2,9-dimethylphenanthroline)
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(Chemical Equation Presented) [cis-Ru(II)(dmp)2(H 2O)2]2+ (dmp = 2,9-dimethylphenanthroline) was found to be a selective oxidation catalyst using hydrogen peroxide as oxidant. Thus, primary alkenes were very efficiently oxidized via direct carbon-carbon bond cleavage to the corresponding aldehydes as an alternative to ozonolysis. Secondary alkenes were much less reactive, leading to regioselective oxidation of substrates such as 4-vinylcyclohexene and 7-methyl-1,6-octadiene at the terminal position. Primary allylic alcohols were chemoselectively oxidized to the corresponding allylic aldehydes, e.g., geraniol to citral.
- Kogan, Vladimir,Quintal, Miriam M.,Neumann, Ronny
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p. 5039 - 5042
(2007/10/03)
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- User- and eco-friendly hypervalent iodine reagent and method of synthesis
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The present invention is a user- and eco-friendly hypervalent iodine reagent (mIBX) capable of selectively oxidizing allylic and benzylic alcohols in water and other eco-friendly solvents and having generally the following structure: 1Allylic and benzylic alcohols are cleanly oxidized to the corresponding carbonyl compounds in water or water-THF mixtures, or other mixtures, using a water-soluble o-iodoxybenzoic acid derivative of the present invention.
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Page Sheet 2
(2010/02/05)
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- A convenient one-pot PCC oxidation-Wittig reaction of alcohols
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A simple one-pot process for the PCC oxidation of alcohols followed by in situ trapping of the aldehyde with a Wittig reagent is described.
- Bressette, Andrew R.,Glover IV, Louis C.
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p. 738 - 740
(2007/10/03)
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- Mild and selective oxidation of alcohols and deoximation of oximes over supported quinolinium fluorochromate
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Quinolinium fluorochromate supported over silica gel selectively brings about the oxidation of a wide variety of alcohols and oxidative deoximation of certain aldoximes and ketoximes to the corresponding carbonyl compounds in good yield. The reagent selectively oxidises primary hydroxyl group in the presence of secondary hydroxyl group. The selectivity is also exhibited in the oxidation of axial hydroxyl group of the cis-4-t-butyl cyclohexanol in preference to equitorial hydroxyl group. Further the reagent is stable even after a period of twelve weeks of its storage.
- Rajkumar, G. Abraham,Sivamurugan,Arabindoo, Banumathi,Murugesan
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p. 936 - 946
(2007/10/03)
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- Tandem oxidation processes for the preparation of functionalized cyclopropanes
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(Chemical Equation Presented) A novel manganese dioxide-mediated tandem oxidation process (TOP) has been developed which allows the direct conversion of allylic alcohols into cyclopropanes, the intermediate aldehydes being trapped in situ with a stabilized sulfur-ylide. This methodology has been applied successfully to a variety of allylic alcohols and to a formal synthesis of the simple, naturally occurring lignan, (±)-picropodophyllone.
- Oswald, Magalie F.,Raw, Steven A.,Taylor, Richard J. K.
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p. 3997 - 4000
(2007/10/03)
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- Polyfluorinated quaternary ammonium salts of polyoxometalate anions: Fluorous biphasic oxidation catalysis with and without fluorous solvents
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[Matrix presented] Polyfluorinated quaternary ammonium cations, [CF 3(CF2)7(CH2)3] 3CH3N+ (RFN+), were synthesized and used as countercations for the [WZnM2(H 2O)2(ZnW9O34)2] 12- (M = Mn(II), Zn(II)) polyoxometalate. The (RFN +)12[WZnM2(H20)2 (ZnW9O34)2] compounds were fluorous biphasic catalysts for alcohol and alkenol oxidation, and alkene epoxidation with aqueous hydrogen peroxide. Reaction protocols with or without a fluorous solvent were tested. The catalytic activity and selectivity was affected by both the hydrophobicity of the solvent and the substrate.
- Maayan, Galia,Fish, Richard H.,Neumann, Ronny
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p. 3547 - 3550
(2007/10/03)
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- Synthesis and oxidation reactions of a user- and eco-friendly hypervalent iodine reagent
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Allylic and benzylic alcohols are cleanly oxidized to the corresponding carbonyl compounds in water or water-THF mixtures using a water-soluble derivative of o-iodoxybenzoic acid. A mechanism involving single electron transfer steps is proposed for this facile and eco-friendly oxidation protocol.
- Thottumkara, Arun P,Vinod, Thottumkara K
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p. 569 - 572
(2007/10/03)
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- Oxygen transfer from sulfoxides: Selective oxidation of alcohols catalyzed by polyoxomolybdates
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Benzylic, allylic, and aliphatic alcohols are oxidized to aldehydes and ketones in a reaction catalyzed by Keggin-type polyoxomolybdates, PVxMo(12-x)O40-(3+x) (x = 0, 2), with DMSO as a solvent. The oxidation of benzylic alcohols is quantitative within hours and selective, whereas that of allylic alcohols is less selective. Oxidation of aliphatic alcohols is slower but selective. Further mechanistic studies revealed that, for H3PMo12O40 as a catalyst and benzylic alcohols as substrates, the sulfoxide is in fact an oxygen donor in the reaction. Postulated reaction steps as determined from isotopelabeling experiments, kinetic isotope effects, and Hammett plots include (a) sulfoxide activation by complexation to the polyoxometalate and (b) oxygen transfer from the activated sulfoxide and elimination of water from the alcohol. The mechanism is supported by the reaction kinetics.
- Khenkin, Alexander M.,Neumann, Ronny
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p. 7075 - 7079
(2007/10/03)
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- Quinones as co-catalysts and models for the surface of active carbon in the phosphovanadomolybdate-catalyzed aerobic oxidation of benzylic and allyilic alcohols: Synthetic, kinetic, and mechanistic aspects
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Quinones have been considered as reactive compounds present on the surface of active carbon. Thus, the co-catalytic use of quinones combined with the phosphovanadomolybdate polyoxometalate, PV2Mo10O405-, has been studied as an analogue of the known PV2Mo10O405-/C catalyst in oxidative dehydrogenation reactions. From the synthetic point of view both biphasic the quinone (org)-Na5PV2Mo10O40 (aq) and monophasic quinone (org)4Q5PV2Mo10O40-(org) [4Q: (nC4H9)4N+] systems are effective for the selective oxidation of benzylic and allylic alcohols to their corresponding aldehydes. Kinetic measurements carried out on the model oxidative dehydrogenation of 4-methylbenzyl alcohol in the presence of p- chloranil, 4Q5PV2Mo10O40, and molecular oxygen showed that the reaction was non-elementary, although the 4-methylbenzyl alcohol oxydehydrogenation was the rate-determining step. ESR measurements showed the presence of the semiquinone of p-chloranil, probably as a complex with the polyoxometalate. This proposed complex was shown to be a more potent oxidant than p-chloranil. Thus, for the oxidation of 4-methoxytoluene the semiquinone complex was active, whereas p-chloranil alone was inactive. Beyond the importance of understanding quinone-phosphovanadomolybdate polyoxometalatecatalyzed reactions, insight gained from the formation of semiquinone active species can be applied for heterogeneous and aerobic oxidative transformations catalyzed by PV2Mo10O405- with carbon matrices as active supports.
- Neumann, Ronny,Khenkin, Alexander M.,Vigdergauz, Inga
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p. 875 - 882
(2007/10/03)
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- Catalytic oxidation of alcohols into aldehydes and ketones by an osmium- copper bifunctional system using molecular oxygen
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The oxidation of allylic and benzylic alcohols to aldehydes can be carried out at room temperature as low as 25°C with molecular oxygen, in the presence of the bifunctional osmium-copper system OsO4-CuCl acting as the catalyst.
- Coleman, Karl S.,Coppe, Maurice,Thomas, Christophe,Osborn, John A.
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p. 3723 - 3726
(2007/10/03)
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- Convenient one pot conversion of acetals into alcohols
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Various acetals are conveniently converted into alcohols using a one pot procedure that combines hydrolysis of an acetal by triflouromethanesulfonic acid in tetrahydrofuran and tert-butylamine borane reduction of the resulting aldehyde.
- Lukin, Kirill A.,Yang, ChengXi,Bellettini, John R.,Narayanan,Leanna, M. Robert,Rasmussen, Michael
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- Chemoselective Oxidation of Alcohols to Aldehydes and Ketones by tert -Butyl Hydroperoxide Catalyzed by a Ruthenium Complex of N,N′,N″-Trimethyl-1,4,7-triazacyclononane
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An operationally simple method based on [Cn*RuIII(CF3CO2) 3·H2O] (Cn* = N,N′,N″-trimethyl-1,4,7-triazacyclononane) catalyst and 1-1.2 equiv of tert-butyl hydroperoxide as terminal oxidant is effective for selective transformation of alcohols to aldehydes and ketones in methylene chloride. The reaction proceeds in high yield and selectivity. Preparation of benzaldehyde (98% yield) from benzyl alcohol on a 200 mmol scale can be performed without modification of the procedure such as slow addition of the oxidant or cooling to 0°C, and catalyst turnovers of 700 are achieved. Oxidation of geraniol which contains an isolated trisubstituted C=C bond leads to geranial selectively without oxidation of the C=C bond. Results from Hammett correlation studies (ρ = -0.47) and primary kinetic isotope effect (kH/kD = 4.8) for the catalytic benzyl alcohol oxidations are inconsistent with an oxoruthenium (O=Ru) based mechanism. A mechanism involving reactive tBuO·/tBuOO· radicals is also excluded based on results from previous works: Cheng, W.-C.; Fung, W.-H.; Che, C.-M. J. Mol. Catal. (A) 1996, 113, 311; absence of di-tert-butyl peroxide; and using cumyl hydroperoxide as a radical probe. A tert-butylperoxoruthenium complex is postulated to be the active intermediate.
- Fung, Wai-Hong,Yu, Wing-Yiu,Che, Chi-Ming
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p. 2873 - 2877
(2007/10/03)
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- Catalysis of giant palladium cluster complexes, highly selective oxidations of primary allylic alcohols to (α,β-unsaturated aldehydes in the presence of molecular oxygen
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A giant Pd cluster, Pd561phen60(OAc)180 has high catalytic activity for the selective oxidations of various primary allylic alcohols to the corresponding α,β-unsaturated aldehydes in the presence of molecular oxygen under mild reaction conditions. A Pd cluster anchored on TiO2, also catalyzes the above oxidations; the heterogeneous Pd561 cluster catalyst is easily separated from the reaction mixture and is reusable.
- Kaneda, Kiyotomi,Fujie, Yoko,Ebitani, Kohki
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p. 9023 - 9026
(2007/10/03)
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