- Aromatic amide derivatives of 5,6-dimethoxy-2,3-dihydro-1H-inden(-1-yl)acetic acid as anti-inflammatory agents free of ulcerogenic liability
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Amide derivatives of 5,6-dimethoxy-2,3-dihydro-1H-inden(-1-yl)acetic acid were synthesized and evaluated for their anti-inflammatory and analgesic activity. Few selected compounds were also screened for their antipyretic, anti-arthritic, and ulcerogenic potential. Most of the compounds exhibited good activity profile and were free of gastrointestinal toxicity of common NSAIDs. However these compounds failed to decrease secondary lesions of adjuvant induced arthritis and also did not inhibit TNF-α in lipopolysaccharide induced pyresis.
- Sharma, Meenakshi,Ray
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- Efficient synthesis of α-substituted-α-arylmethyl phosphonates using trichloroacetimidate C–C coupling method
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A simple convenient protocol for the synthesis of diethyl α,α-diaryl methylphosphonate derivatives 5a-f, 6b-f, 7a-f and 8a-f, diethyl α-alkenyl α-aryl methylphosphonates 9a-d and 10a-d and α-(oxoalkyl) α-aryl methylphosphonate 11a-d and 12a-d is described. Trichloroacetimidates 3a-d were treated with activated arenes, styrene, allyltrimethylsilane or silylenol ethers C-nucleophiles in the presence TMSOTf to afford the desired products in good yields and short reaction time.
- Fathalla, Walid,Pazdera, Pavel,El-Rayes, Samir,Ali, Ibrahim.A.I.
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- Oxidation of alcohols with benzyltriphenylphosphonium peroxymonosulfate under non-aqueous conditions
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Oxidation of allylic and benzylic alcohols with benzyltriphenylphosphonium peroxymonosulfate (PhCH2Ph3P+HSO5-) 1 (BTPPMS) in refluxing acetonitrile is reported. The oxidation in the presence of a catalytic amount of bismuth chloride enhances the rate.
- Hajipour,Mallakpour,Adibi
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- Co-Oxidative Transformation of Piperine to Piperonal and 3,4-Methylenedioxycinnamaldehyde by a Lipoxygenase from Pleurotus sapidus
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The valuable aroma compound piperonal with its vanilla-like olfactory properties is of high interest for the fragrance and flavor industry. A lipoxygenase (LOXPsa1) of the basidiomycete Pleurotus sapidus was identified to convert piperine, the abundant pungent principle of black pepper (Piper nigrum), to piperonal and a second volatile product, 3,4-methylenedioxycinnamaldehyde, with a vanilla-like odor through an alkene cleavage. The reaction principle was co-oxidation, as proven by its dependence on the presence of linoleic or α-linolenic acid, common substrates of lipoxygenases. Optimization of the reaction conditions (substrate concentrations, reaction temperature and time) led to a 24-fold and 15-fold increase of the piperonal and 3,4-methylenedioxycinnamaldehyde concentration using the recombinant enzyme. Monokaryotic strains showed different concentrations of and ratios between the two reaction products.
- Krahe, Nina-Katharina,Berger, Ralf G.,Kahlert, Lukas,Ersoy, Franziska
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- Benzyltriphenylphosphonium peroxymonosulfate: As a novel and efficient reagent for oxidation of alcohols under solvent-free conditions
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This paper describes the oxidation of alcohols under solvent-free conditions using benzyltriphenylphosphonium peroxymonosulfate, which has been prepared by mixing an aqueous solution of benzyltriphenylphosphonium chloride with oxone at room temperature. This reagent is stable white powder, which may be stored for months without loss of its activity. This compound is readily soluble in organic solvents such as acetonitrile, chloroform, and dichloromethane and slightly soluble in carbon tetrachloride, ether, and hexane.
- Hajipour, Abdol Reza,Mallakpour, Shadpour E.,Adibi, Hadi
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- Sphingobacterium sp. T2 Manganese Superoxide Dismutase Catalyzes the Oxidative Demethylation of Polymeric Lignin via Generation of Hydroxyl Radical
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Sphingobacterium sp. T2 contains two extracellular manganese superoxide dismutase enzymes which exhibit unprecedented activity for lignin oxidation but via an unknown mechanism. Enzymatic treatment of lignin model compounds gave products whose structures were indicative of aryl-Cα oxidative cleavage and demethylation, as well as alkene dihydroxylation and alcohol oxidation. 18O labeling studies on the SpMnSOD-catalyzed oxidation of lignin model compound guiaiacylglycerol-β-guaiacyl ether indicated that the an oxygen atom inserted by the enzyme is derived from superoxide or peroxide. Analysis of an alkali lignin treated by SpMnSOD1 by quantitative 31P NMR spectroscopy demonstrated 20-40% increases in phenolic and aliphatic OH content, consistent with lignin demethylation and some internal oxidative cleavage reactions. Assay for hydroxyl radical generation using a fluorometric hydroxyphenylfluorescein assay revealed the release of 4.1 molar equivalents of hydroxyl radical by SpMnSOD1. Four amino acid replacements in SpMnSOD1 were investigated, and A31H or Y27H site-directed mutant enzymes were found to show no lignin demethylation activity according to 31P NMR analysis. Structure determination of the A31H and Y27H mutant enzymes reveals the repositioning of an N-terminal protein loop, leading to widening of a solvent channel at the dimer interface, which would provide increased solvent access to the Mn center for hydroxyl radical generation.
- Rashid, Goran M. M.,Zhang, Xiaoyang,Wilkinson, Rachael C.,Fül?p, Vilmos,Cottyn, Betty,Baumberger, Stéphanie,Bugg, Timothy D. H.
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- Synthesis and biological evaluation of amide derivatives of (5,6-dimethoxy-2,3-dihydro-1H-inden-1-yl)acetic acid as anti-inflammatory agents with reduced gastrointestinal ulcerogenecity
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A variety of amide derivatives of (5,6-dimethoxy-2,3-dihydro-1H-inden-1-yl)acetic acid were synthesized and screened for their analgesic and anti-inflammatory activities. The compounds were found to have longer activity profile exceeding that of indomethacin in carrageenan-induced rat paw edema model. Few selected compounds were also screened for their antipyretic, anti-arthritic and ulcerogenecity potential. From these studies it can be concluded that these compounds though have significant antipyretic activity did not act through the inhibition of TNF-α. The test compounds failed to prevent the development of secondary inflammation in adjuvant-induced arthritis assay. However, these compounds showed no ulcer formation at the tested dose level of 100 mg/kg p.o.
- Sharma, Meenakshi,Ray
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- Oxidative deprotection of trimethylsilyl and tetrahydropyranyl ethers and ethylene acetals with benzyltriphenylphosphonium peroxomonosulfate in the presence of bismuth chloride under non-aqueous conditions
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Benzyltriphenylphosphonium peroxomonosulfate (BnPh3P+HSO5-) (1) is used as a new reagent for oxidative deprotection of trimethylsilyl and tetrahydropyranyl ethers and ethylene acetals to afford carbonyl compounds in refluxing acetonitrile in the presence of bismuth chloride.
- Hajipour,Mallakpour,Mohammadpoor-Baltork,Adibi
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- The Oxidation of 3-Aryl-1-propenes by Oxidative System of RuCl 3-NaIO4-Phase Transfer Catalyst
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Methyleugenol 1a was oxidized to give 3,4-dimethoxyphenylacetaldehyde by the oxidative system containing the RuCl3-NaIO4-phase transfer catalyst. The yield and spectroscopic properties were obtained from the stable acetaldoxim 3a. Furthermore, this oxidation system could be applied to other arylpropenes, thus, safrole, 4-methoxyallylbenzene, allylbenzene, and the corresponding arylacetaldehyde formed.
- Yuasa, Yoshifumi,Shibuya, Shiroshi,Yuasa, Yoko
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- Ferrocenyl chalcones with O-alkylated vanillins: synthesis, spectral characterization, microbiological evaluation, and single-crystal X-ray analysis
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O-alkylated vanillin derivatives 2a–f and acetylferrocene react under Claisen–Schmidt conditions, resulting in good-to-high yields of the corresponding ferrocene chalcones 3a–f. None of the resultant compounds 3b–f has been previously described in the literature. All synthesized compounds were characterized by spectral and physical data, whereas two of them, 1-ferrocenyl-3-(4-ethoxy-3-methoxyphenyl)-prop-2-en-1-one (3b) and 1-ferrocenyl-3-(4-buthoxy-3-methoxy-phenyl)-prop-2-en-1-one (3e), were crystalline substances, suitable for single-crystal X-ray analysis, which confirmed undoubtedly their structures. Chalcones 3a–f were tested for their biological activity and demonstrated relatively good in vitro antimicrobial activity towards different strains of bacteria and fungi. The best antibacterial activity is expressed by compounds 3b and 3c, while compound 3d shows the best antifungal activity.
- Mu?kinja, Jovana,Burmud?ija, Adrijana,Ratkovi?, Zoran,Rankovi?, Branislav,Kosani?, Marijana,Bogdanovi?, Goran A.,Novakovi?, Sla?ana B.
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- Comparing the catalytic efficiency of ring substituted 1- hydroxybenzotriazoles as laccase mediators
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A series of ring substituted 1-hydroxybenzotriazoles (6-X-HBTs) have been tested as mediators in the laccase-promoted oxidation of 4-methoxybenzyl alcohol, 3,4-dimethoxybenzyl alcohol, and the dimeric lignin model 1-(3,4-dimethoxyphenyl)-2-phenoxyethanol.
- D'Alfonso, Claudio,Lanzalunga, Osvaldo,Lapi, Andrea,Vadalà, Raffaella
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- Nickel-catalyzed Ullmann-type coupling reaction to prepare tetra-ortho-substituted biaryls
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A nickel-catalyzed Ullmann-type reaction on the coupling of bis-ortho-substituted arylhalides to prepare tetra-ortho-biaryls was brought about in moderate to high yields. Bu4NI might function as an efficient bridging ligand to accelerate the formation of dinickel-center intermediate, which subsequently eliminates to desired coupling product.
- Hong,Hoen,Zhang,Lin
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- ORTHO-HYDROXYLATION SELECTIVE DES PHENOLS : II - UN NOUVEAU SYSTEME CATALYTIQUE A CARACTERE PREPARATIF.
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A direct synthetic transformation of phenols into copper(II) catecholates (i.e. catechols) is described, which involves a copper-catalyzed activation of molecular oxygen.The mechanism and scope of this new reaction are discussed.
- Capdevielle, Patrice,Maumy, Michel
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- An efficient and selective oxidation of benzylic alcohols to the corresponding carbonyl compounds under solvent-free conditions
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1-Benzyl-4-aza-1-azoniabicyclo[2.2.2]octanedichromate is a useful reagent for selective oxidation of benzylicalcohols and α-hydroxy ketones to the corresponding carbonyl compounds. The reaction was carried out under solvent-free conditions without or in the presence of a catalytic amount of aluminum chloride.
- Hajipour, Abdol Reza,Mallakpour, Shadpour E.,Mohammadpoor-Baltork, Iraj,Khoee, Sepideh
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- Organocatalytic Chemoselective Primary Alcohol Oxidation and Subsequent Cleavage of Lignin Model Compounds and Lignin
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A one-pot two-step degradation of lignin β-O-4 model compounds initiated by preferred oxidation of the primary over the secondary hydroxyl groups with a TEMPO/DAIB system has been developed [TEMPO=2,2,6,6-tetramethylpiperidine-N-oxyl, DAIB=(diacetoxy)iodobenzene]. The oxidised products are then cleaved by proline-catalysed retro-aldol reactions. This degradation methodology produces simple aromatics in good yields from lignin model compounds at room temperature with an extension to organosolv beech-wood lignin (L1) resulting in known cleavage products.
- Dabral, Saumya,Hernández, José G.,Kamer, Paul C. J.,Bolm, Carsten
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- Structural requirements for ipso-nitration with cerium(IV) ammonium nitrate (CAN)
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Compounds in which the carbon skeleton contains at least a diarylmethane with the aromatic rings appropriately substituted by electron donating groups exhibited ipso-nitration when treated with cerium(IV) ammonium nitrate (CAN).
- Asghedom,LaLonde,Ramdayal
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- Factors Controlling the Reactivity of a Ligninase Model Based on the Association of Potassium Monopersulfate to Manganese and Iron Porphyrin Complexes
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An efficient ligninase model based on the association of potassium monopersulfate to iron and manganese porphyrin in solution or immobilized onto an ion-exchange resin is reported.High catalytic conversion of veratryl alcohol or 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol, a useful model molecule for checking the ability of cleaving Cα-Cβ bonds of arylglycerol-β-aryl ether linkages existing in lignin itself, is obtained at room temperature in a single-phase solution (buffered water/acetonitrile, 75/25, v/v) at pH 2-3 for iron porphyrin or at pH 4.5-6.0 for manganese porphyrin.The porphyrin ligand used in the present study is the meso-tetrakis(p-sulfonatophenyl)porphyrin (TPPS).Catalytic activities can be as high as eight cycles per second.
- Labat, Gilles,Meunier, Bernard
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- Synergistic effect of vanadium-phosphorus promoted oxidation of benzylic alcohols with molecular oxygen in water
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The synergistic effect of vanadium-phosphorus in aqueous solution is crucial to ensure high efficiency for oxidation of benzylic alcohols with molecular oxygen in water catalyzed by VOPO4/TEMPO (2,2,6,6-tetramethylpiperidyl-1-oxy).
- Du, Zhongtian,Ma, Jiping,Ma, Hong,Gao, Jin,Xu, Jie
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- Biomimetic oxidation of veratryl alcohol with H2O2 catalyzed by iron(III) porphyrins and horseradish peroxidase in ionic liquid
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3,4-Dimethoxybenzyl alcohol (veratryl alcohol) is a model compound for lignin substructures and its oxidation with H2O2 catalyzed by iron(III) porphyrins and horseradish peroxidase (HRP) in ionic liquids has been described. Veratraldehyde and 2-hydroxymethyl-5-methoxy-2,5-cyclohexadiene- 1,4-dione were the two major products of the oxidation of veratryl alcohol at room temperature. The iron(III) porphyrin or HRP immobilized in ionic liquids showed increased catalytic activity and can be recycled and this is believed due to the stabilization of highvalent oxoiron(IV) π-cation radical intermediate generated in the reaction. Georg Thieme Verlag Stuttgart.
- Kumar, Anil,Jain, Nidhi,Chauhan
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- Copper-Mediated Conversion of Complex Ethers to Esters: Enabling Biopolymer Depolymerisation under Mild Conditions
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Selective processing of the β-O-4 unit in lignin is essential for the efficient depolymerisation of this biopolymer and therefore its successful integration into a biorefinery set-up. An approach is described in which this unit is modified to incorporate a carboxylic ester with the goal of enabling the use of mild depolymerisation conditions. Inspired by preliminary results using a Cu/TEMPO/O2 system, a protocol was developed that gave the desired β-O-4-containing ester in high yield using certain dimeric model compounds. The optimised reaction conditions were then applied to an oligomeric lignin model system. Extensive 2D NMR analysis demonstrated that analogous chemistry could be achieved with the oligomeric substrate. Mild depolymerisation of the ester-containing oligomer delivered the expected aryl acid monomer.
- Xiao, Ganyuan,Montgomery, James R. D.,Lancefield, Christopher S.,Panovic, Isabella,Westwood, Nicholas J.
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- The unusual characteristics of the aerobic oxidation of 3,4-dimethoxytoluene with metal/bromide catalysts
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DMtoluene (3,4-dimethoxytoluene; DM = 3,4-dimethoxy), a model compound for lignin oxidation, can be autoxidized in acetic acid using a Co/Mn/Br catalyst to its benzaldehyde in 51 mol % yield, and to its acid in 85-92 mol % yield. This synthesis is unusual because a number of unprecedented phenomena occur. 1) The rate of molecular oxygen reacting with the substrate is bi-phasic, i.e., two maximum in the rate of reaction are observed. 2) In the first phase, all of the 3,4-dimethoxytoluene is converted to intermediates, but very little to the carboxylic acid. 3) During the second maximum of activity, virtually all the intermediates are converted to the carboxylic acid with 95-100% mass accountability. 4) The rate of carbon monoxide and carbon dioxide formation is considerably higher during the second phase during which 5) 9-12% of methyl 3,4-dimethoxybenzoate (the methyl ester of the benzoic acid) is formed. Mechanisms are suggested for these unusual phenomena.
- Partenheimer, Walt
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- Regeneration of aldehydes from bisulfite addition products in the solid state using montmorillonite KSF clay under microwave irradiation
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Microwave irradiation of bisulfite addition products with montmorillonite KSF clay under solvent-free conditions provides a fast, efficient and simple method for regeneration of aldehydes in excellent yields.
- Mitra, Alok Kumar,De, Aparna,Karchaudhuri, Nilay
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- CeCl3·7H2O-promoted highly chemoselective hydrolysis of 1,3-oxathio- and dithioacetals
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A highly selective hydrolysis of the 1,3-oxathio- and 1,3-dithioacetals has been achieved in high yields using CeCl3·7H2O-NaI in acetonitrile at reflux temperature under neutral conditions. This method is mild and compatible with a wide range of functional groups such as TBDPS, THP, PMB, MOM, allyl, propargyl, prenyl, benzyl ethers, carbamates and acetate, etc., present in the substrate.
- Yadav,Reddy,Raghavendra,Satyanarayana
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- Convenient photooxidation of alcohols using dye sensitised zinc oxide in combination with silver nitrate and TEMPO
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A novel photooxidative system using dye sensitised zinc oxide in combination with silver nitrate and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) in an aqueous solution is described. Under visible light irradiation the selective oxidation of alcoh
- Jeena, Vineet,Robinson, Ross S.
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- Bioinspired aerobic oxidation of alcohols with a bifunctional ligand based on bipyridine and TEMPO
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A novel bioinspired bifunctional ligand incorporating metal-binding site and stable free radical has been synthesized. The catalytic system obtained from the bifunctional ligand with copper(i) iodide in the presence of N-methylimidazole is highly efficient for the oxidation of a broad range of primary benzylic, allylic, alkynyl, aliphatic alcohols and secondary benzylic alcohols to the corresponding aldehydes and ketones in good to excellent yields. The catalyst system exhibits broad functional-group compatibility. The reaction is carried out in acetonitrile as solvent under air balloon at room temperature. The catalyst system features excellent activity for primary aliphatic alcohol oxidation and a high chemoselective oxidation of primary alcohols over the secondary alcohols. This oxidation process is readily amenable to larger-scale application. The interaction of the different components in the reaction mixtures was studied by UV-visible spectroscopy. The data indicated that Cu(i) existed throughout the reaction. A plausible mechanism of the catalytic cycle is proposed.
- Wang, Lianyue,Bie, Zhixing,Shang, Sensen,Lv, Ying,Li, Guosong,Niu, Jingyang,Gao, Shuang
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- Copper(II)-catalyzed aerobic oxidation of primary alcohols to aldehydes in ionic liquid [bmpy]PF6
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(Chemical Equation Presented) A room-temperature aerobic oxidation of primary alcohols to aldehydes catalyzed by the three-component system acetamido-TEMPO/Cu-(ClO4)2/DMAP in the ionic liquid [bmpy]PF6 has been developed, and the catalysts can be recycled and reused for five runs without any significant loss of catalytic activity.
- Jiang, Nan,Ragauskas, Arthur J.
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- Effects of alkoxy groups on arene rings of lignin β-O-4 model compounds on the efficiencies of single electron transfer-promoted photochemical and enzymatic C-C bond cleavage reactions
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To gain information about how alkoxy substitution in arene rings of β-O-4 structural units within lignin governs the efficiencies/rates of radical cation C1-C2 bond cleavage reactions, single electron transfer (SET) photochemical and lignin peroxidase-catalyzed oxidation reactions of dimeric/tetrameric model compounds have been explored. The results show that the radical cations derived from less alkoxy-substituted dimeric β-O-4 models undergo more rapid C1-C2 bond cleavage than those of more alkoxy-substituted analogues. These findings gained support from the results of DFT calculations, which demonstrate that C1-C2 bond dissociation energies of β-O-4 radical cations decrease as the degree of alkoxy substitution decreases. In SET reactions of tetrameric compounds consisting of two β-O-4 units, containing different degrees of alkoxy substitution, regioselective radical cation C-C bond cleavage was observed to occur in one case at the C1-C2 bond in the less alkoxy-substituted β-O-4 moiety. However, regioselective C1-C2 cleavage in the more alkoxy-substituted β-O-4 moiety was observed in another case, suggesting that other factors might participate in controlling this process. These observations show that lignins containing greater proportions of less rather than more alkoxylated rings as part of β-O-4 units would be more efficiently cleaved by SET mechanisms.
- Lim, Suk Hyun,Nahm, Keepyung,Ra, Choon Sup,Cho, Dae Won,Yoon, Ung Chan,Latham, John A.,Dunaway-Mariano, Debra,Mariano, Patrick S.
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- Aromatic Hydroxylation. Hydroxybenzaldehydes from Bromobenzaldehydes via Reaction of in Situ Generated, Lithiated α-Morpholinobenzyl Alkoxides with Nitrobenzene
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A general method for the one-step conversion of bromobenzaldehydes to the corresponding hydroxybenzaldehydes has been developed.The method involves in situ protection of the aldehyde function of the bromobenzaldehyde as its lithium morpholinoalkoxide, followed by lithium-bromine exchange, reaction with nitrobenzene at -75 deg C, and a subsequent acidic workup.The method has been applied to the synthesis of 4,5-dimethoxy-3-hydroxy- (1a), 3,5-dimethoxy-2-hydroxy- (2a), 3,5-bis(benzyloxy)-2-hydroxy- (2b), 3,4-dimethoxy-2-hydroxy- (14), 3-hydroxy-4,5-(methylenedioxy)- (16), and 4,5-dimethoxy-2-hydroxybenzaldehydes (18) from the bromobenzaldehydes 4, 12a, 12b, 13, 15, and 17, respectively.
- Sinhababu, Achintya K.,Borchardt, Ronald T.
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- Green Synthesis of Veratraldehyde Using Potassium Promoted Lanthanum-Magnesium Mixed Oxide Catalyst
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Veratraldehyde is an important chemical used in perfumery, agrochemical, and pharmaceutical industries. Current processes of manufacture of veratraldehyde use homogeneous catalysts, which make them highly polluting, creating problems of disposal of effluents and product purity. In the current work, veratraldehyde was synthesized from O-alkylation of vanillin with an environmentally benign reagent, dimethyl carbonate. A series of potassium loaded La2O3-MgO were prepared by the incipient wetness impregnation method, and their performance was evaluated vis-à-vis MgO, La2O3, La2O3-MgO, and a series of 1-4 wt % K/La2O3-MgO. All catalysts were characterized by different techniques, such as N2 adsorption/desorption, XRD, TGA-DSC, FT-IR, CO2-TPD, and SEM techniques. The effect of different loadings (1-4 wt %) of potassium on La2O3-MgO was studied, among which 2 wt % K/La2O3-MgO showed the best activity and selectivity due to high dispersion of potassium and high basicity in comparison with the rest. The activity of 2 wt % K/La2O3-MgO in O-methylation of vanillin with dimethyl carbonate (DMC) was closely associated with basicity. Various parameters were studied to achieve the maximum yield of the desired product. The maximum conversion was found with catalyst loading of 0.03 g/cm3 and mole ratio of vanillin and DMC of 1:15 at 160 °C in 2 h. The reaction follows pseudo-first-order kinetics for the O-methylation of vanillin. The energy of activation was found to be 13.5 kcal/mol. Scale-up was done using the kinetic model to observe that the process could be scaled up using the process parameters. The overall process is clean and green.
- Molleti, Jayaram,Yadav, Ganapati D.
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- Solid-phase oxidative halodecarboxylation of β-arylacrylic acids with the ceric ammonium nitrate-alkali halide system
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The solid-phase oxidation of cinnamic, 4-methoxy- and 3,4-dimethoxycinnamic acids with Ce(NH4)2(NO3)6-MHal system leads to β-halostyrenes. Similar procedure in the absence of a metal halide results in a cleavage of the C=C bond giving the corresponding benzaldehydes.
- Nikishin,Sokova,Makhaev,Kapustina
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- Oxidation of benzylic alcohols to their corresponding carbonyl compounds using ceric ammonium nitrate (CAN)/broensted acidic ionic liquid
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A chemoselective and efficient procedure for the oxidation of alcohols to the corresponding carbonyl compounds is reported using ceric ammonium nitrate in the presence of 3-methylimidazolium hydrogensulfate as Broensted acidic ionic liquid ([Hmim]HSO4) as the solvent under mild conditions. The use of non-toxic and inexpensive materials, straightforward procedure, short reaction times and good yields of the products are the major advantages of this method.
- Hajipour,Khazdooz,Ruoho
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- Ceric ammonium nitrate in organic synthesis II. Oxidation of N,N-dimethyl methoxyphenylmethylamines to methoxybenzaldehydes
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N,N-Dimethylmethoxyphenylmethylamines were selectively converted to the corresponding methoxybenzaldehydes using Ceric Ammonium Nitrate (CAN) in acetonitrile/water.
- Badea,Cotelle,Catteau
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- An efficient sonochemical oxidation of benzyl alcohols into benzaldehydes by FeCl3/HNO3 in acetone
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Sonochemical oxidation of benzyl alcohols into corresponding aldehydes by FeCl3/HNO3 in acetone at room temperature has been reported. All substrates give good yield of the products within 10-25 min. The reaction of selected substrates were also studied under reflux and at the room temperature. Further, various Lewis acids were used to evaluate their catalytic efficacy.
- Naik, Ramesh,Nizam, Aatika,Siddekha, Aisha,Pasha
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- Lifetime of veratryl alcohol radical cation electrogenerated in acetonitrile
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The electrochemical oxidation of veratryl alcohol at a carbon fiber microdisk electrode with relatively high sweep rates in acetonitrile shows a chemically reversible response. Analysis of the cathodic and anodic current ratio allows one to estimate the lifetime of the short-lived radical cation in the solution.
- Kishioka, Shin-Ya,Yamada, Akifumi
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- Design, synthesis and evaluation of phthalide alkyl tertiary amine derivatives as promising acetylcholinesterase inhibitors with high potency and selectivity against Alzheimer's disease
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A series of phthalide alkyl tertiary amine derivatives were designed, synthesized and evaluated as potential multi-target agents against Alzheimer's disease (AD). The results indicated that almost all the compounds displayed significant AChE inhibitory and selective activities. Besides, most of the derivatives exhibited increased self-induced Aβ1-42 aggregation inhibitory activity compared to the lead compound DL-NBP, and some compounds also exerted good antioxidant activity. Specifically, compound I-8 showed the highest inhibitory potency toward AChE (IC50 = 2.66 nM), which was significantly better than Donepezil (IC50 = 26.4 nM). Moreover, molecular docking studies revealed that compound I-8 could bind to both the catalytic active site and peripheral anionic site of AChE. Furthermore, compound I-8 displayed excellent BBB permeability in vitro. Importantly, the step-down passive avoidance test indicated that I-8 significantly reversed scopolamine-induced memory deficit in mice. Collectively, these results suggested that I-8 might be a potent and selective AChE inhibitor for further anti-AD drug development.
- Cao, Zhongcheng,Deng, Yong,Li, Yan,Luo, Li,Qiang, Xiaoming,Song, Qing,Tan, Zhenghuai
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- Electrochemical Aminoxyl-Mediated Oxidation of Primary Alcohols in Lignin to Carboxylic Acids: Polymer Modification and Depolymerization
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An electrochemical process has been developed for chemoselective oxidation of primary alcohols in lignin to the corresponding carboxylic acids. The electrochemical oxidation reactions proceed under mildly basic conditions and employ 2,2,6,6-tetramethyl-1-piperidine N-oxyl (TEMPO) and 4-acetamidoO (ACT) as catalytic mediators. Lignin model compounds and related alcohols are used to conduct structure-reactivity studies that provide insights into the origin of the reaction selectivity. The method is applied to the oxidation of lignin extracted from poplar wood chips via a mild acidolysis method, and the reaction affords a novel polyelectrolyte material. Gel permeation chromatography data for the oxidized lignin shows that this material has a molecular weight and molecular weight distribution very similar to that of the extracted lignin, but notable differences are also evident. Base titration reveals a significant increase in the acid content, and the oxidized lignin has much higher water solubility relative to the extracted lignin. Treatment of the oxidized lignin under acidic conditions results in depolymerization of the material into characterized aromatic monomers in nearly 30 wt% yield.
- Rafiee, Mohammad,Alherech, Manar,Karlen, Steven D.,Stahl, Shannon S.
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- Kinetics and mechanism of the reactions of ozone with guaiacol, veratrol, and veratrol derivatives
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The kinetics of the reactions of ozone with compounds modeling structural lignin fragments, viz., phenol, guaiacol, veratrol, veratric aldehyde, and veratric alcohol, was studied. The reaction rate constants were calculated using the mass transfer model for the chemical reaction based on the film theory. The rate constants of the reactions of ozone with compounds of the veratryl series were calculated by the Hammett equation. The major ozonation products of the studied compounds were determined by HPLC. The ozonation mechanism was proposed.
- Khudoshin,Mitrofanova,Lunin
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- Iridium-catalyzed oppenauer oxidations of primary alcohols using acetone or 2-butanone as oxidant
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The first Oppenauer oxidation of primary alcohols with acetone or 2-butanone by an amino alcohol-based Ir bifunctional catalyst was accomplished. The reaction proceeds with 1 mol % catalyst in acetone or 2-butanone at 30-80 °C to give the corresponding aldehydes in 33-96% yield.
- Suzuki, Takeyuki,Morita, Kenji,Tsuchida, Mika,Hiroi, Kunio
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- Exploring the Electronic Properties of Extended Benzofuran-Cyanovinyl Derivatives Obtained from Lignocellulosic and Carbohydrate Platforms Raw Materials
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Two series of linear extended benzofuran derivatives associating cyanovinyl unit and phenyl or furan moieties obtained from benzaldehyde-lignocellulosic (Be series) or furaldehyde –saccharide (Fu series) platforms were prepared in order to investigate their emission and electrochemical properties. For the fluorescence in solution and solid states, contrasting results between the two series were demonstrated. For Be series a net aggregation induced emission effect was observed with high fluorescence quantum yield for the solid state. A [2+2] cycloaddition under irradiation at 350 nm was also revealed for one derivative of Be series. In contrast, for Fu series the fluorescence in solution is higher than in the solid state. The X-ray crystallography studies for the compounds reveal the formation of strong π-π stacking for the derivatives without emissive property in the solid state and the presence of essentially lateral contacts for emissive compounds. Taking advantage of the propensity to develop 2D π-stacking mode for the more extended derivative with a central furan cycle, organic field effect transistors presenting hole mobility have been made.
- Ibrahim, Nagham,Moussallem, Chady,Allain, Magali,Segut, Olivier,Gohier, Frédéric,Frère, Pierre
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Read Online
- A PROCESS FOR THE PREPARATION OF VANILLIN AND OTHER SUBSTITUTED PHENYLALDEHYDES
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The present invention relates to a chemical process for the production of substituted phenylaldehydes such as vanillin (1a) from substituted phenylpropenes or substituted phenylpropenes enriched essential oils such as eugenol (2a) or eugenol rich essential oils indiscriminately through either cis or trans or a mixture of cis and trans isomer(s) of substituted phenylprop-2-enes such as isoeugenol, an intermediate compound. The invention relates to the conversion of substituted phenylpropenes to other substituted phenylaldehydes, particularly vanillin without the protection of the phenolic group, therefore, it offers a step economy. The present chemical process involves the use of class 3 and 4 solvents thereby devoid of the use of any chlorinated solvent.
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- Visible-Light-Induced Selective C-C Bond Cleavage Reactions of Dimeric β-O-4 and β-1 Lignin Model Substrates Utilizing Amine-Functionalized Fullerene
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Finding a selective and efficient fragmentation process under ambient conditions is pivotal for the generation of fuels and chemical feedstocks from lignoceullosic biomass. In the present study, visible-light and amine-functionalized fullerene-based photocatalyst-promoted photodegradation reactions of dimeric β-O-4 and β-1 lignin model compounds, containing varying numbers of methoxy substituents on the arene ring, were explored to find and develop mild, eco-friendly photochemical techniques for efficient delignification. The results showed that, in contrast to well-known organic photoredox catalysts, amine-functionalized fullerene photocatalyst promoted photochemical reactions of lignin model compounds could lead to more efficient lignin fragmentation reactions through a pathway involving a selective Cα-Cβ bond cleavage process, and in addition, Cα-hydroxyl moiety in lignin model compounds played a significant role in the success of the Cα-Cβ bond cleavage reaction of lignin model substrates.
- Cho, Dae Won,Jang, Hannara,Kim, Min-Ji,Kim, Young-Il,Lim, Dong Hyun,Lim, Suk Hyun,Wee, Kyung-Ryang
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p. 2289 - 2300
(2022/02/07)
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- Studies directed toward the synthesis of hedycoropyrans: total synthesis of des-hydroxy (?)-hedycoropyran B (ent-rhoiptelol B)
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A full account of our efforts directed towards the synthesis of the diarylheptanoid-derived natural products hedycoropyrans that led to the total synthesis of ent-rhoiptelol B is described. In this endeavor, we have attempted two distinct synthetic strategies to access hedycoropyrans A and B, which led us to establish a facile synthetic route for des-hydroxy (?)-hedycoropyran B (ent-rhoiptelol B) from simple and readily accessible building blocks of 4-allylanisole and vanillin, employing Sharpless asymmetric epoxidation, CBS reduction, and an intramolecular AgOTf-catalyzed oxa-Michael reaction of suitably functionalized hydroxy-ynone as key transformations. The investigations disclosed herein will provide insights into designing novel synthetic routes for THP-DAH-derived natural products.
- Kataria, Priyanka,Nomula, Rajesh,Kontham, Ravindar
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p. 444 - 463
(2022/01/20)
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- Visible-Light-Driven Oxidative Cleavage of Alkenes Using Water-Soluble CdSe Quantum Dots
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The oxidative cleavage of C=C bonds is an important chemical reaction, which is a popular reaction in the photocatalytic field. However, high catalyst-loading and low turnover number (TON) are general shortcomings in reported visible-light-driven reactions. Herein, the direct oxidative cleavage of C=C bonds through water-soluble CdSe quantum dots (QDs) is described under visible-light irradiation at room temperature with high TON (up to 3.7×104). Under the same conditions, water-soluble CdSe QDs could also oxidize sulfides to sulfoxides with 51–84 % yields and TONs up to 3.4×104. The key features of this photocatalytic protocol include high TONs, wide substrates scope, low catalyst loadings, simple and mild reaction conditions, and molecular O2 as the oxidant.
- Li, Jianing,Zhao, Jingnan,Ma, Cunfei,Yu, Zongyi,Zhu, Hongfei,Yun, Lei,Meng, Qingwei
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p. 4985 - 4992
(2021/10/16)
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- Synthesis of Azepino[1,2-a]indole-10-amines via [6+1] Annulation of Ynenitriles with Reformatsky Reagent
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Lewis acid-catalyzed [6+1] annulation reactions of 2-cyano-1-propargyl- and 2-alkynyl-1-cyanomethyl-indoles with Reformatsky reagent are described. 8-Aryl, 8-alkyl-, 8-hetaryl-, 9-aryl, and 9-alkyl-azepino[1,2-a]indole amines were obtained through a 7-endo-mode cyclization of the β-aminoacrylate intermediates. The antiproliferative activity of the azepino[1,2-a]indoles analogs against the HCT-116 cells were also examined.
- Iioka, Ryoya,Yorozu, Kohei,Sakai, Yoko,Kawai, Rika,Hatae, Noriyuki,Takashima, Katsuki,Tanabe, Genzoh,Wasada, Hiroaki,Yoshimatsu, Mitsuhiro
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supporting information
p. 1553 - 1558
(2021/02/26)
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- Molecular iodine mediated oxidative cleavage of the C-N bond of aryl and heteroaryl (dimethylamino)methyl groups into aldehydes
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The oxidative cleavage of the C-N bond of aryl and heteroaryl (dimethylamino)methyl groups is achieved by employing molecular iodine as a mild oxidizing agent under ambient conditions in the presence of a mild base. The important reaction of C3 formylation of free NH and substituted indoles containing various substituents is accomplished from the corresponding Mannich bases. This methodology can also be extended for the synthesis of aryl and other heteroaryl aldehydes and ketones. Furthermore, the usefulness of the method is successfully demonstrated on a gram scale.
- Mandrekar, Ketan S.,Tilve, Santosh G.
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supporting information
p. 4152 - 4155
(2021/03/15)
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- Selective aerobic oxidation of benzylic and allylic alcohols catalyzed by Cu(OAc)2/TEMPO/Et2NH
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Selective oxidation of benzylic and allylic alcohols to their corresponding aldehyde/ketone derivative without affecting saturated alcohols is still a challenging endeavor in organic synthesis. Various metal complexes, especially the copper complexes in the presence of TEMPO are being used very often for such transformations under aerobic conditions, but they are not selective to allylic and benzylic alcohols. The use of copper salt for oxidation of alcohols in the absence of a ligand are very scarcely studied except for the one catalyzed by CuCl/TEMPO where chloride inhibition and lack of selective oxidation have been noted upon use of CuCl2. Herein we report a Cu(OAc)2 catalyzed and TEMPO mediated selective aerobic oxidation of benzylic and allylic alcohols to aldehyde/ketone in the presence of Et2NH. The method avoids pre-synthesis of the catalyst as in the case of Cu(II)/(I) complexes/TEMPO catalyzed oxidation reactions, requires low catalyst loading, employs cheaper copper salt, and gives excellent selectivity for oxidation of benzylic and allylic alcohols.
- Bez, Ghanashyam,Gogoi, Achinta,Pasupuleti, Bala Gangadhar
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p. 589 - 597
(2021/09/28)
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- Chemoselective and ligand-free aerobic oxidation of benzylic alcohols to carbonyl compounds using alumina-supported mesoporous nickel nanoparticle as an efficient recyclable heterogeneous catalyst
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An economically efficient and operationally simple ligand-free protocol for the chemoselective oxidation of benzylic alcohols to carbonyl compounds has been developed using alumina-supported nickel nanoparticles as a stable recyclable heterogeneous catalyst along with potassium tert-butoxide in the presence of aerial oxygen as an eco-friendly oxidant. The aliphatic alcohols remained unaffected under the present condition. Excellent chemoselectivity has also been demonstrated through intermolecular and intramolecular competition experiments. This protocol accommodates a diverse range of substituents with the tolerance of various sensitive moieties during the reaction. The catalyst could be recovered by filtration and reused consecutively without any significant loss in the catalytic activity. Moreover, the heterogeneity of the catalyst has also been established by the “hot filtration method (Sheldon's test)”.
- Das, Asit Kumar,Nandy, Sneha,Bhar, Sanjay
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- V2O5@TiO2 Catalyzed Green and Selective Oxidation of Alcohols, Alkylbenzenes and Styrenes to Carbonyls
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The versatile application of different functional groups such as alcohols (1° and 2°), alkyl arenes, and (aryl)olefins to construct carbon-oxygen bond via oxidation is an area of intense research. Here, we report a reusable heterogeneous V2O5@TiO2 catalyzed selective oxidation of various functionalities utilizing different mild and eco-compatible oxidants under greener reaction conditions. The method was successfully applied for the alcohol oxidation, oxidative scission of styrenes, and benzylic C?H oxidation to their corresponding aldehydes and ketones. The utilization of mild and eco-friendly oxidizing reagents such as K2S2O8, H2O2 (30 % aq.), TBHP (70 % aq.), broad substrate scope, gram-scale synthesis, and catalyst recyclability are notable features of the developed protocol.
- Upadhyay, Rahul,Kumar, Shashi,Maurya, Sushil K.
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p. 3594 - 3600
(2021/07/02)
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- Selective Aerobic Oxidation of Benzyl Alcohols with Palladium(0) Nanoparticles Suspension in Water
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Abstract: This study concerns one of the rare applications of a suspension of palladium nanoparticles in water for oxidation reactions. The aqueous suspension containing well dispersed nanoparticles of 3.85?nm was obtained following a straightforward procedure involving the reduction of Na2PdCl4 with NaBH4 in the presence of PVP as stabilizing agent. In the way of oxidative catalytic valorisation of lignin, the aqueous suspension was directly applied as catalytic medium for the selective oxidation of vanillic alcohol into vanillin (80?°C, O2, 1?h) with more than 90% yield. Reusability of the catalytic medium has been demonstrated, acting as “quasi-homogeneous catalyst”. More sophisticated lignin-derived substrates like veratryl alcohol and hydrobenzoin gave yields of 50–80% to the respective aldehyde and ketone. In parallel, this as-synthesized suspension was directly used to prepare a Pd/TiO2 catalyst, the latter showing less efficiency for the catalytic transformations. Graphic Abstract: [Figure not available: see fulltext.]
- Bourbiaux, Dolorès,Mangematin, Stéphane,Djakovitch, Laurent,Rataboul, Franck
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p. 3239 - 3249
(2021/03/16)
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- Structural and Biochemical Studies Enlighten the Unspecific Peroxygenase from Hypoxylon sp. EC38 as an Efficient Oxidative Biocatalyst
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Unspecific peroxygenases (UPOs) are glycosylated fungal enzymes that can selectively oxidize C-H bonds. UPOs employ hydrogen peroxide as the oxygen donor and reductant. With such an easy-to-handle cosubstrate and without the need for a reducing agent, UPOs are emerging as convenient oxidative biocatalysts. Here, an unspecific peroxygenase from Hypoxylon sp. EC38 (HspUPO) was identified in an activity-based screen of six putative peroxygenase enzymes that were heterologously expressed in Pichia pastoris. The enzyme was found to tolerate selected organic solvents such as acetonitrile and acetone. HspUPO is a versatile catalyst performing various reactions, such as the oxidation of prim- and sec-alcohols, epoxidations, and hydroxylations. Semipreparative biotransformations were demonstrated for the nonenantioselective oxidation of racemic 1-phenylethanol rac-1b (TON = 13 000), giving the product with 88% isolated yield, and the oxidation of indole 6a to give indigo 6b (TON = 2800) with 98% isolated yield. HspUPO features a compact and rigid three-dimensional conformation that wraps around the heme and defines a funnel-shaped tunnel that leads to the heme iron from the protein surface. The tunnel extends along a distance of about 12 ? with a fairly constant diameter in its innermost segment. Its surface comprises both hydrophobic and hydrophilic groups for dealing with substrates of variable polarities. The structural investigation of several protein-ligand complexes revealed that the active site of HspUPO is accessible to molecules of varying bulkiness with minimal or no conformational changes, explaining the relatively broad substrate scope of the enzyme. With its convenient expression system, robust operational properties, relatively small size, well-defined structural features, and diverse reaction scope, HspUPO is an exploitable candidate for peroxygenase-based biocatalysis.
- Ebner, Katharina,Glieder, Anton,Kroutil, Wolfgang,Mattevi, Andrea,Rinnofner, Claudia,Rotilio, Laura,Swoboda, Alexander
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p. 11511 - 11525
(2021/09/22)
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- Ruthenium-on-Carbon-Catalyzed Facile Solvent-Free Oxidation of Alcohols: Efficient Progress under Solid-Solid (Liquid)-Gas Conditions
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A protocol for the ruthenium-on-carbon (Ru/C)-catalyzed solvent-free oxidation of alcohols, which proceeds efficiently under solid-solid (liquid)-gas conditions, was developed. Various primary and secondary alcohols were transformed to corresponding aldehydes and ketones in moderate to excellent isolated yields by simply stirring in the presence of 10% Ru/C under air or oxygen conditions. The solvent-free oxidation reactions proceeded efficiently regardless of the solid or liquid state of the substrates and reagents and could be applied to gram-scale synthesis without loss of the reaction efficiency. Furthermore, the catalytic activity of Ru/C was maintained after five reuse cycles.
- Park, Kwihwan,Jiang, Jing,Yamada, Tsuyoshi,Sajiki, Hironao
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p. 1200 - 1205
(2021/12/29)
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- Method for catalytically synthesizing aromatic aldehyde by lewis acid
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The invention discloses a method for catalytically synthesizing aromatic aldehyde by lewis acid, the method specifically comprises the following steps: firstly, adding an ether substance, an organic solvent and lewis acid into a reaction tube, placing the reaction tube in an ice-water bath at the temperature of 0 DEG C, dropwise adding an aldehyde reagent, reacting for 0.5 hour, and stirring the reaction tube at room temperature for 0.5 hour to obtain a reaction solution; and extracting, drying with sodium sulfate, and separating with silica gel column chromatography to obtain the aromatic aldehyde. Aromatic aldehyde is synthesized through a mild and cheap method, and a target compound is obtained at room temperature. The method is easy to operate, low in reaction energy consumption, low in synthesis cost and environment-friendly in technology, and is expected to be applied to the fields of organic synthesis and medicinal chemistry.
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Paragraph 0030-0052
(2021/08/07)
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- ISOINDOLE DERIVATIVE
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Disclosed is a compound of formula (I) and a stereoisomer thereof: wherein R1, R2, R3 and R4 are as defined in the present disclosure.
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Paragraph 0233
(2021/02/25)
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- Polycarboxylated compounds and compositions containing same
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Methods of selectively modifying lignin, polycarboxylated products thereof, and methods of deriving aromatic compounds therefrom. The methods comprise electrochemically oxidizing lignin using stable nitroxyl radicals to selectively oxidize primary hydroxyls on β-O-4 phenylpropanoid units to corresponding carboxylic acids while leaving the secondary hydroxyls unchanged. The oxidation results in polycarboxylated lignin in the form of a polymeric β-hydroxy acid. The polymeric β-hydroxy acid has a high loading of carboxylic acid and can be isolated in acid form, deprotonated, and/or converted to a salt. The β-hydroxy acid, anion, or salt can also be subjected to acidolysis to generate various aromatic monomers or oligomers. The initial oxidation of lignin to the polycarboxylated form renders the lignin more susceptible to acidolysis and thereby enhances the yield of aromatic monomers and oligomers obtained through acidolysis.
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Page/Page column 22-23
(2021/06/09)
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- Nickel catalyzed hydrosilane reduction of (het)arenecarboxylic acids into aldehydes
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Nickel-catalyzed reduction of (het)arenecarboxylic acids with hydrosilanes in the presence of dimethyl dicarbonate as the activator affords the corresponding aldehydes. The role of the activator is the conversion of the acids into their anhydrides undergoing C–O cleavage. The good yields were achieved in case of substrates bearing electron-donating and electron-neutral groups.
- Wang, Liang,Wang, Yaoyao,Tao, Yu,Zhang, Nana,Li, Shubai
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p. 271 - 273
(2021/05/04)
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- Preparation method of 3, 4-dimethoxybenzaldehyde
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The invention provides a preparation method of 3, 4-dimethoxybenzaldehyde, which belongs to the technical field of organic synthesis, and the preparation method provided by the invention comprises the following steps: mixing o-anisole and a Lewis acid catalyst, introducing hydrogen chloride gas until the system pressure is 0.2-0.5 MPa, heating to the temperature of oxidation reaction, introducing carbon monoxide gas, and carrying out an oxidation reaction to obtain the 3, 4-dimethoxybenzaldehyde. The preparation method provided by the invention uses few raw materials, and the raw materials are wide in source and low in cost; and the preparation process is simple and few three wastes are generated. Furthermore, the preparation method provided by the invention is simple in post-treatment and easy to operate and purify. Data of the embodiment show that the yield of the 3, 4-dimethoxybenzaldehyde prepared by adopting the preparation method provided by the invention is 92.3%, and the gas phase content is 99.7%.
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Paragraph 0062-0080
(2021/04/21)
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- Organic Electrochemistry: Expanding the Scope of Paired Reactions
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Paired electrochemical reactions allow the optimization of both atom and energy economy of oxidation and reduction reactions. While many paired electrochemical reactions take advantage of perfectly matched reactions at the anode and cathode, this matching of substrates is not necessary. In constant current electrolysis, the potential at both electrodes adjusts to the substrates in solution. In principle, any oxidation reaction can be paired with any reduction reaction. Various oxidation reactions conducted on the anodic side of the electrolysis were paired with the generation and use of hydrogen gas at the cathode, showing the generality of the anodic process in a paired electrolysis and how the auxiliary reaction required for the oxidation could be used to generate a substrate for a non-electrolysis reaction. This is combined with variations on the cathodic side of the electrolysis to complete the picture and illustrate how oxidation and reduction reactions can be combined.
- Moeller, Kevin D.,Wu, Tiandi
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supporting information
p. 12883 - 12890
(2021/05/07)
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- Samarium-based Grignard-type addition of organohalides to carbonyl compounds under catalysis of CuI
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Grignard-type additions were readily achieved under the mediation of CuI (10 mol%) and samarium (2 equiv.) by employing various organohalides,e.g.benzyl, aryl, heterocyclic and aliphatic halides (Cl, Br or I), and diverse carbonyl compounds (e.g.carbonic esters, carboxylic esters, acid anhydrides, acyl chlorides, ketones, aldehydes, propylene epoxides and formamides) to afford alcohols, ketones and aldehydes, respectively, with high efficiency and chemoselectivity, in which the organosamarium intermediate might be involved.
- Liu, Chen,Liu, Yongjun,Qi, Yan,Song, Bin,Wang, Liang,Xiao, Shuhuan
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supporting information
p. 6169 - 6172
(2021/06/30)
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- Transaminase-mediated synthesis of enantiopure drug-like 1-(3′,4′-disubstituted phenyl)propan-2-amines
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Transaminases (TAs) offer an environmentally and economically attractive method for the direct synthesis of pharmaceutically relevant disubstituted 1-phenylpropan-2-amine derivatives starting from prochiral ketones. In this work, we report the application of immobilised whole-cell biocatalysts with (R)-transaminase activity for the synthesis of novel disubstituted 1-phenylpropan-2-amines. After optimisation of the asymmetric synthesis, the (R)-enantiomers could be produced with 88-89% conversion and >99% ee, while the (S)-enantiomers could be selectively obtained as the unreacted fraction of the corresponding racemic amines in kinetic resolution with >48% conversion and >95% ee. This journal is
- Lakó, ágnes,Mendon?a, Ricardo,Molnár, Zsófia,Poppe, László
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p. 40894 - 40903
(2020/11/23)
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- A metal-free heterogeneous photocatalyst for the selective oxidative cleavage of CC bonds in aryl olefins: via harvesting direct solar energy
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Selective cleavage of CC bonds is highly important for the synthesis of carbonyl containing fine chemicals and pharmaceuticals. Novel methodologies such as ozonolysis reactions, Lemieux-Johnson oxidation reaction etc. already exist. Parallel to these, catalytic methods using homogeneous catalysts also have been discovered. Considering the various advantages of heterogeneous catalysts such as recyclability and stability, couple of transition metal-based heterogeneous catalysts have been applied for this reaction. However, the pharmaceutical industries prefer to use metal-free catalysts (especially transition metal-free) to avoid further leaching in the final products. This is for sure a big challenge to an organic chemist and to the pharmaceutical industries. To make this feasible, a mild and efficient protocol has been developed using polymeric carbon nitrides (PCN) as metal-free heterogeneous photocatalysts to convert various olefins into the corresponding carbonyls. Later, this catalyst has been applied in the gram scale synthesis of pharmaceutical drugs using direct solar energy. Detailed mechanistic studies revealed the actual role of oxygen, the catalyst, and the light source.
- Das, Shoubhik,Hatami, Nareh,Jooss, Christian,Lange, Niklas Simon,Ronge, Emanuel,Schilling, Waldemar,Zhang, Yu
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supporting information
p. 4516 - 4522
(2020/08/10)
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- Potent human dihydroorotate dehydrogenase inhibitory activity of new quinoline-4-carboxylic acids derived from phenolic aldehydes: Synthesis, cytotoxicity, lipophilicity and molecular docking studies
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A series of novel 2-substituted quinoline-4-carboxylic acids was synthesized by Doebner reaction starting from freely available protocatechuic aldehyde and vanillin precursors. Human dihydroorotate dehydrogenase (hDHODH) was recognised as a clear molecular target for these heterocycles. All compounds were also tested for their antiproliferative potential against three cancer cells (MCF-7, A549, A375) and one normal cell line (HaCaT) to evaluate the selective cytotoxicity. Quinoline derivatives 3f and 3g were identified as potent hDHODH inhibitors while 3k and 3l demonstrated high cytotoxic activity against MCF-7 and A375 cells and good selectivity. In addition, the logD7.4 values obtained by the experimental method were found to be in the range from ?1.15 to 1.69. The chemical structures of all compounds were confirmed by IR, NMR and elemental analysis. The compounds pharmacology on the molecular level was revealed by means of molecular docking, highlighting the structural differences that distinguish highly active from medium and low active hDHODH inhibitors.
- Petrovi?, Milena M.,Roschger, Cornelia,Chaudary, Sidrah,Zierer, Andreas,Mladenovi?, Milan,Jakovljevi?, Katarina,Markovi?, Violeta,Botta, Bruno,Joksovi?, Milan D.
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- Visible-light mediated facile dithiane deprotection under metal free conditions
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Visible light mediated facile and selective dithiane deprotection under metal free conditions is developed. Eosin Y (1 mol%) proved to be an effective catalyst for the dithiane deprotection under the ambient photoredox conditions. The standard household compact fluorescent light source (CFL bulb) proved to be effective under open-air conditions in aqueous acetonitrile at room temperature. The protocol that exhibits a broad substrate scope and functional group tolerance has been shown to expand to a range of transformations for the electron-rich and -deficient thioacetals and thioketals. The synthetic utility of this protocol has also been demonstrated by gram-scale application.
- Dharpure, Pankaj D.,Bhowmick, Anindita,Warghude, Prakash K.,Bhat, Ramakrishna G.
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- Visible-light assisted of nano Ni/g-C3N4 with efficient photocatalytic activity and stability for selective aerobic C?H activation and epoxidation
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A selective, economical, and ecological protocol has been described for the oxidation of methyl arenes and their analogs to the corresponding carbonyl compounds and epoxidation reactions of alkenes with molecular oxygen (O2) or air as a green oxygen source, under mild reaction conditions. The nano Ni/g-C3N4 exhibited high photocatalytic activity, stability, and selectivity in the C?H activation of methyl arenes, methylene arenes, and epoxidation of various alkenes under visible- light irradiation without the use of an oxidizing agent and under base free conditions.
- Akrami, Zahra,Hosseini-Sarvari, Mona
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supporting information
(2020/10/13)
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- Magnetic nanoparticle supported ionic liquid phase catalyst for oxidation of alcohols
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Anew magnetic nanoparticle supported ionic liquid phase (SILP) catalyst containing perruthenate anions was prepared by a multistep procedure. The various analytical techniques such as FT-IR spectroscopy, X-ray photoelectron spectroscopy, transmission elec
- Naikwade, Altafhusen,Jagadale, Megha,Kale, Dolly,Rashinkar, Gajanan
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p. 1088 - 1097
(2020/10/20)
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- Mpsc6 binuclear complexes immobilized on graphene oxide for oxidation of lignin model compounds and lignin
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An efficient process for the oxidative degradation of lignin using M-GO (MPSC6 binuclear complexes immobilized on graphene oxide) biomimetic catalysts in acetonitrile was developed in this work. Different M-GO catalysts (M=Co, Cu, Zn and Ni) were used to catalyze the depolymerization of lignin model compounds and organosolv lignin. The results showed that the immobilization of MPSC6 complexes on GO was favorable for regulating the valuable depolymerization of the model compounds and lignin. The optimal solid catalyst Co-GO exhibited high catalytic activity, which showed a 83.04% conversion of phenolic β-O-4 lignin model compound, a 91.26% conversion of veratryl alcohol and a 96.24% conversion of vanillyl alcohol with a catalyst/model compound ratio of 50 mg:10 mmol and a dosage of 15 mmol H2O2 at 80 °C for 3 h. The stuctural changes of organosolv lignin occurred in catalytic oxidation were analyzed in terms of O/C ratio, molecular weight and OH content of lignin samples, and a plausible mechanism involving the formation of aromatic products and muconolactone from lignin depolymerization over M-GO was also proposed.
- Yang, Xiao-Jun,Zhou, Xue-Fei,Zou, Zheng-Rong
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p. 973 - 982
(2021/06/26)
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- Spinel Structured Copper Ferrite Nano Catalyst with Magnetic Recyclability for Oxidative Decarboxylation of Phenyl Acetic Acids
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Abstract: A simple, efficient and environmentally benign method has been discussed for the synthesis of aldehydes and ketones by the oxidative decarboxylation of phenylacetic acid under ligand free condition using simple, efficient, preparatively easy, magnetically recoverable and low cost spinel CuFe2O4 nanoparticles. The catalyst was characterised using powder-XRD, FTIR, FE-SEM, EDX, VSM and HRTEM. The recyclability was examined and the results showed that the catalyst remained almost equally active up to five consecutive cycles. Graphic Abstract: Spinel Structured Copper Ferrite is a very efficient nano catalyst for Oxidative decarboxylation of Phenyl acetic acids and can be reused up to five cycles without significant loss in catalytic activity.[Figure not available: see fulltext.].
- Rahman, Taskia,Borah, Geetika,Gogoi, Pradip K.
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p. 2267 - 2272
(2020/02/18)
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- Selective production of bio-based aromatics by aerobic oxidation of native soft wood lignin in tetrabutylammonium hydroxide
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Aerobic oxidation of native soft wood lignin in an aqueous solution of Bu4NOH facilitates efficient production of vanillin (4-hydroxy-3-methoxybenzaldehyde), which is one of the platform chemicals in industry. Oxidation of Japanese cedar (Cryptomeria japonica) wood flour at 120 °C for 4 h under O2in Bu4NOH-based aqueous solutions produced vanillin in 23.2 wt% yield based on the Klason lignin content of the starting material. This yield was comparable to that in alkaline nitrobenzene oxidation of the same material (27.2%), which indicated that our aerobic oxidation exploited the full potential of the wood flour for vanillin production. Further mechanical investigation with lignin model compounds suggested that the vanillin formation occurred mainly through following successive reactions: alkaline-catalyzed degradation of ?-ether linkages in middle units of lignin polymer to form a glycerol end group, oxidation of the glycerol end group by O2to a HCa?O moiety, and release of vanillin from the HCa?O end. One of the reasons for the high performance of Bu4NOH for the vanillin production was explained by the general understanding in organic chemistry that Bu4OH is a stronger base than simple alkali,e.g.NaOH. The other more fundamental mechanical aspect was that Bu4N+suppressed disproportionation of the vanillin precursor (the CaHO end group) probably due to strong interaction between the cation and the HCa?O end group.
- Hosoya, Takashi,Miyafuji, Hisashi,Yamada, Tatsuhiko,Yamamoto, Kohei
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p. 19199 - 19210
(2020/06/04)
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- A PROCESS FOR THE PRODUCTION OF OXIDIZED WOOD PRODUCTS
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The present invention relates to a process for the production of oxidized wood products, comprising step a) reacting chips of one or more wood products in a basic solution at a p H between 8 and 14 under an oxygen atmosphere at a pressure of at least 0.1 MPa, or at least 0.9 MPa. A copper catalyst may be used in the process.
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Page/Page column 19; 20
(2020/08/22)
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- Visible-light-induced C-C bond cleavage of lignin model compounds with cyanobenziodoxolone
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The catalytic degradation of lignin to value-added chemicals has received considerable attention over the past decade. Photocatalysis provides promising approaches to enable previously inaccessible transformations. However, examples of the visible-light promoted degradation of lignin are still limited. In this work, the visible-light-induced selective C-C bond cleavage of β-O-4 lignin model compounds has been disclosed via β-scission of in situ generated alkoxy radical intermediates. With cyanobenziodoxolone as the oxidant, a variety of substrates could be transformed into aldehydes in moderate to good yields. In addition, unexpected acetal esters which could conveniently furnish formaldehyde and phenols by alcoholysis were observed.
- Zheng, Ming,Huang, Yan,Zhan, Le-Wu,Hou, Jing,Li, Bin-Dong
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- Cleavage of CC and Co bonds in β-O-4 linkage of lignin model compound by cyclopentadienone group 8 and 9 metal complexes
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Degradation of 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphe-noxy)propane-1,3-diol (1), a model compound for lignin β-O-4 linkage was examined with iron, ruthenium, rhodium and iridium complexes bearing cyclopentadienone ligand. Cyclopentadienone iron complex gave only a small amount of degraded product with reduced molecular weight. Cyclopentadienone ruthenium complex, so called Shvo's catalyst, afforded 3,4-dimethoxybenzaldehyde (a3) in 14.3% yield after CαCβ bond cleavage. On the other hand, cyclopentadienone group-9 metal complexes catalyzed CβO bond cleavage to afford guaiacol (b1) as a main product in up to 74.9% yield.
- Kishino, Masamichi,Kusumoto, Shuhei,Nozaki, Kyoko
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supporting information
p. 477 - 480
(2020/05/19)
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- Visible-light-induced oxidative lignin c-c bond cleavage to aldehydes using vanadium catalysts
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Lignin is the largest carrier of aromatics on earth, and its depolymerization can afford value-Added aromatic products. Direct cleavage of the C-C bonds in lignin linkages is significant, but it is challenging to obtain low-molecular-weight aromatic monomers. Herein, using vanadium catalysts under visible light, we selectively cleave the C-C bonds in β-1 and β-O-4 interlinkages occluded in lignin models and extracts by an oxidative protocol. Visible light irradiation triggered single electron transfer between the substrate and the catalyst, which further induced the selective Cα-Cβ bond cleavage and generated the final aromatic products through radical intermediates. Using this photocatalytic chemistry, the reactivity of lignin models and the selectivity of Cα-Cβ bond cleavage were significantly improved. More importantly, this protocol affords aromatic monomers through the fragmentation of organosolv lignins even at room temperature, indicating the potential of photocatalytic C-C bond cleavage of lignin linkages under ambient conditions.
- Liu, Huifang,Li, Hongji,Luo, Nengchao,Wang, Feng
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p. 632 - 643
(2020/01/02)
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- Method for preparing aldehyde compounds through photocatalytic oxidation cracking β - hydroxyl compound C-C bond
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The invention provides a method for preparing aldehydes from C-C bonds of beta-hydroxy compounds by photocatalytic oxidative cracking. According to the method, the beta-hydroxy compounds are taken asa substrate, oxygen-containing gas is taken as an oxygen source, and C-C bond cracked products, namely, corresponding aldehydes can be generated under illumination in presence of a catalyst. The conditions are mild, the oxidation efficiency and the product yield are high, and the oxygen-containing gas is taken as the oxygen source under the illumination condition, so that the method is economical,environmentally friendly and green, meets the strategy of sustainable developed energy and has broad application prospect.
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Paragraph 0056; 0057
(2020/07/29)
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- New hybrid pyrazole and imidazopyrazole antinflammatory agents able to reduce ROS production in different biological targets
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Several anti-inflammatory agents based on pyrazole and imidazopyrazole scaffolds and a large library of substituted catechol PDE4D inhibitors were reported by us in the recent past. To obtain new molecules potentially able to act on different targets involved in inflammation onset we designed and synthesized a series of hybrid compounds by linking pyrazole and imidazo-pyrazole scaffolds to differently decorated catechol moieties through an acylhydrazone chain. Some compounds showed antioxidant activity, inhibiting reactive oxygen species (ROS) elevation in neutrophils, and a good inhibition of phosphodiesterases type 4D and, particularly, type 4B, the isoform most involved in inflammation. In addition, most compounds inhibited ROS production also in platelets, confirming their ability to exert an antiinflammatory response by two independent mechanism. Structure–activity relationship (SAR) analyses evidenced that both heterocyclic scaffolds (pyrazole and imidazopyrazole) and the substituted catechol moiety were determinant for the pharmacodynamic properties, even if hybrid molecules bearing to the pyrazole series were more active than the imidazopyrazole ones. In addition, the pivotal role of the catechol substituents has been analyzed. In conclusion the hybridization approach gave a new serie of multitarget antiinflammatory compounds, characterized by a strong antioxidant activity in different biological targets.
- Brullo, Chiara,Massa, Matteo,Rapetti, Federica,Alfei, Silvana,Bertolotto, Maria B.,Montecucco, Fabrizio,Signorello, Maria Grazia,Bruno, Olga
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- Directly Microwave-Accelerated Cleavage of C?C and C?O Bonds of Lignin by Copper Oxide and H2O2
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Model erythro, phenolic, and nonphenolic lignin β-O-4 dimer compounds are treated with copper oxide and H2O2 at the electronic field maximum position of a single-mode 2.45 GHz microwave system equipped with a cavity resonator. The products obtained through microwave heating and oil-bath heating with the same reaction vessel and temperature profile are quantitatively compared. Dimer degradation is found to proceed through consecutive elementary reactions. The phenolic dimer is dehydroxylated and this is followed by the spontaneous cleavage of Cα?Cβ and C?O?C bonds to produce guaiacol, vanillin, and vanillic acid. The reaction of the nonphenolic dimer produces veratric acid, veratraldehyde, and guaiacol. Microwave irradiation accelerates cleavage of the side chain and the oxidation of vanillin to vanillic acid. However, no acceleration of veratraldehyde oxidation to veratric acid or aromatic ring cleavage to produce dicarboxylic acids is observed. The selective acceleration of elementary reactions during the degradation of model lignin compounds indicates that microwaves interact with reaction intermediates that are sensitive to electromagnetic waves.
- Qu, Chen,Ito, Keigo,Katsuyama, Isamu,Mitani, Tomohiko,Kashimura, Keiichiro,Watanabe, Takashi
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p. 4510 - 4518
(2020/05/18)
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- Design, synthesis and antitumour and anti-angiogenesis evaluation of 22 moscatilin derivatives
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Two series of moscatilin derivatives were designed, synthesized and evaluated as anti-tumor and anti-angiogenesis agents. Most of these compounds showed moderate-to-obvious cytotoxicity against five cancer cell lines (A549, HepG2, MDA-MB-231, MKN-45, HCT116). Among these cell lines, compounds had obvious effects on HCT116. Especially for 8Ae, the IC50 was low to 0.25 μM. 8Ae can inhibit the viability and induce the apoptosis of HCT116 cells but exhibit no cytotoxic activity in noncancerous NCM460 colon cells. 8Ae can also arrest the G2/M cell cycle in HCT116 cells by inhibiting the α-tubulin expression. Zebrafish bioassay-guided screen showed the 22 moscatilin derivatives had potent anti-angiogenic activities and compound 8Ae had better activities than positive compound. Molecular docking indicated 8Ae interacted with tubulin at the affinity of ?7.2 Kcal/mol. In conclusion, compound 8Ae was a potential antitumor and anti-angiogenesis candidate for further development.
- Guan, Li,Zhou, Junting,Lin, Qinghua,Zhu, Huilin,Liu, Wenyuan,Liu, Baolin,Zhang, Yanbo,Zhang, Jie,Gao, Jing,Feng, Feng,Qu, Wei
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p. 2657 - 2665
(2019/05/01)
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- Organosuperbase dendron manganese complex grafted on magnetic nanoparticles; heterogeneous catalyst for green and selective oxidation of ethylbenzene, cyclohexene and oximes by molecular oxygen
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Magnetic Fe3O4 nanoparticles as a support were modified with an amino-terminated organosilicon and cyanoric choloride ligands. The novel manganese complex was grafted on modified magnetic support (Mn(II)-Met@MMNPs). The nanocatalyst structure, particle size, morphology and surface properties was well characterized by elemental analysis, ICP-AES, AAS, EDS, FT-IR, SEM, TEM, DLS, VSM, TGA, XRD and XPS. In order to develop an effective heterogeneous nanocatalyst for eco-friendly aerobic, highly active and selective catalytic reactions, synthesized nanocatalyst was applied in oxidation of various organic compounds. The catalytic performance of the manganese nanocatalyst in the aerobic oxidation of ethylbenzene (EB), cyclohexene (CYHE) and various aldoximes and ketoxime were studied. Selective aerobic oxidation of EB and CYHE and various oximes were catalyzed by the Mn-nanocatalyst using N-hydroxyphthalimide (NHPI) with molecular oxygen as the green oxidant without the need of any reducing agent, and respectively the acetophenone (AcPO) as a benzylic product, 2-cyclohexene-1-one (CYHE[dbnd]O) as an allylic product and corresponding carbonyl compounds were obtained. The oxidation process has been optimized for Mn-nanocatalyst by considering the effect of different parameters such as the ratio and amount of Mn-nanocatalyst/NHPI, reaction time and solvent for achieving maximum conversion and selectivity to products. Due to their significant low cost, informal preparation, easy magnetically separation from reaction mixture, excellent catalytic performance, simple recovery and reusability without any metal leaching, the Mn-nanocatalyst has huge application prospect in selective and green oxidation process.
- Faraji, Ali Reza,Ashouri, Fatemeh,Hekmatian, Zahra,Heydari, Somayyeh,Mosazadeh, Sima
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- Aerobic oxidation of alcohols with air catalyzed by decacarbonyldimanganese
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The oxidation of alcohols to carbonyl compounds using air as the terminal oxidant is highly desirable. As described in previous reports, the abstraction of α-H of the alcohol is the most important step, and it typically requires not only a metal catalyst but also complex ligands, co-catalysts and bases. Herein, we report a practical and efficient method for the oxidation of primary alcohols, secondary alcohols, 1,2-diols, 1,2-amino alcohols, and other α-functionalized alcohols using a commercially available catalyst, Mn2(CO)10, and no additives. Preliminary mechanistic studies indicated that an alkoxyl radical intermediate existed in our system, and a plausible mechanism consistent with the experimental results and literature was proposed.
- Meng, Shan-Shui,Lin, Li-Rong,Luo, Xiang,Lv, Hao-Jun,Zhao, Jun-Ling,Chan, Albert S. C.
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supporting information
p. 6187 - 6193
(2019/11/20)
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- A molybdenum based metallomicellar catalyst for controlled and chemoselective oxidation of activated alcohols in aqueous medium
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A surfactant based oxodiperoxo molybdenum complex, which could activate molecular oxygen, has been employed as a catalyst for controlled oxidation of benzylic alcohols to corresponding carbonyls. The oxidation reactions were carried out under aqueous environment, however, in the absence of any extraneous base or co-catalyst. Sensitive/oxidizable functional groups like cyano, sulfide, hydroxyl, aryl-hydroxyl, alkene (internal/terminal), alkyne (internal/terminal), and acetal were tolerated during the transformations. Such selectivity is attributed to the mild nature of the catalyst. The methodology could also be scaled-up for multi-gram synthesis and the protocol is likely to find practical use since it requires an inexpensive recyclable-catalyst and easily available oxidant (under green conditions). A plausible mechanism is proposed with the help of preliminary computational study.
- Thiruvengetam, Prabaharan,Chakravarthy, Rajan Deepan,Chand, Dillip Kumar
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p. 123 - 133
(2019/07/19)
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- Cyclopentadienyl Ruthenium(II) Complex-Mediated Oxidation of Benzylic and Allylic Alcohols to Corresponding Aldehydes
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This work reports an efficient method for the oxidation reaction of aliphatic, aromatic allylic, and benzylic alcohols into aldehydes catalyzed by the cyclopentadienyl ruthenium(II) complex (RuCpCl(PPh3)2) with bubbled O2. Through further optimizing controlled studies, the tendency order of oxidation reactivity was determined as follows: benzylic alcohols > aromatic allylic alcohols >> aliphatic alcohols. In addition, this method has several advantages, including a small amount of catalyst (0.5 mol%) and selective application of high discrimination activity of aliphatic, aromatic allylic, and benzylic alcohols.
- Chern, Ching-Yuh,Tseng, Ching-Chun,Hsiao, Rong-Hong,Wong, Fung Fuh,Kuo, Yueh-Hsiung
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- Nickel(ii)-catalyzed direct olefination of benzyl alcohols with sulfones with the liberation of H2
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A nickel(ii)-catalyzed direct olefination of benzyl alcohols with sulfones to access various terminal and internal olefins with the liberation of hydrogen gas is reported.
- Landge, Vinod G.,Yadav, Vinita,Subaramanian, Murugan,Dangarh, Pragya,Balaraman, Ekambaram
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supporting information
p. 6130 - 6133
(2019/06/03)
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- A Redox Strategy for Light-Driven, Out-of-Equilibrium Isomerizations and Application to Catalytic C-C Bond Cleavage Reactions
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We report a general protocol for the light-driven isomerization of cyclic aliphatic alcohols to linear carbonyl compounds. These reactions proceed via proton-coupled electron-transfer activation of alcohol O-H bonds followed by subsequent C-C β-scission of the resulting alkoxy radical intermediates. In many cases, these redox-neutral isomerizations proceed in opposition to a significant energetic gradient, yielding products that are less thermodynamically stable than the starting materials. A mechanism is presented to rationalize this out-of-equilibrium behavior that may serve as a model for the design of other contrathermodynamic transformations driven by excited-state redox events.
- Ota, Eisuke,Wang, Huaiju,Frye, Nils Lennart,Knowles, Robert R.
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supporting information
p. 1457 - 1462
(2019/01/25)
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- Efficient Oxidation of Benzylic and Aliphatic Alcohols Using a Bioinspired Cross-Bridged Cyclam Manganese Complex with H2O2
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The cross-bridged cyclam manganese complex Mn(Me2EBC)Cl2 efficiently catalyzes the oxidation of benzylic and aliphatic alcohols at pH 3 in a mixture of acetonitrile and water at room temperature. The environmentally benign and high oxygen content oxidant H2O2 was adopted. Conversions of the alcohols to the corresponding carbonyl compounds reached 98 % with good to excellent selectivity. In addition, several lignin model compounds were also catalytically oxidized under these conditions, with excellent conversion (up to 96 %) and selectivity (up to 99 %).
- Zhang, Zhan,Khrouz, Lhoussain,Yin, Guochuan,Andrioletti, Bruno
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supporting information
p. 323 - 327
(2018/11/27)
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- On/Off O2 Switchable Photocatalytic Oxidative and Protodecarboxylation of Carboxylic Acids
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Photoredox catalysis in recent years has manifested a powerful branch of science in organic synthesis. Although merging photoredox and metal catalysts has been a widely used method, switchable heterogeneous photoredox catalysis has rarely been considered. Herein, we open a new window to use a switchable heterogeneous photoredox catalyst which could be turned on/off by changing a simple stimulus (O2) for two opponent reactions, namely, oxidative and protodecarboxylation. Using this strategy, we demonstrate that Au@ZnO core-shell nanoparticles could be used as a switchable photocatalyst which has good catalytic activity to absorb visible light due to the localized surface plasmon resonance effect of gold, can decarboxylate a wide range of aromatic and aliphatic carboxylic acids, have multiple reusability, and are a reasonable candidate for synthesizing both aldehydes/ketones and alkane/arenes in a large-scale set up. Some biologically active molecules are also shown via examples of the direct oxidative and protodecarboxylation which widely provided pharmaceutical agents.
- Bazyar, Zahra,Hosseini-Sarvari, Mona
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p. 13503 - 13515
(2019/10/11)
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- A mild aerobic oxidation of benzyl alcohols and oxidative decarboxylation of phenylacetic acids by cellulose-supported Ag-Ag2S nanoparticles
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Synthesis, characterization and catalytic activity of Ag-Ag2S nanoparticles supported on environmentally benign cellulose matrix has been discussed. The nanoparticles carry out controlled oxidation of benzylic alcohols to aldehydes at room temperature. Same nanoparticles also carry out oxidative decarboxylation of phenylacetic acid and decarboxylation of mandelic acid derivatives to corresponding aldehydes under comparatively milder conditions. Stability and recyclability of the catalyst has been studied. The advantages of the catalyst developed in this work over other previous reports include room temperature or comparatively low temperature reaction, shorter reaction times, no requirement of stoichiometric oxidant or ligands, use of green solvents, functional group tolerance, and recyclability.
- Hussain, Farhaz Liaquat,Suri, Mrinaly,Namdeo, Ashutosh,Borah, Geetika,Dutta, Dipanka,Goswami, Tridip,Pahari, Pallab
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