- A convenient synthesis of 3,4-dimethoxy-5-hydroxybenzaldehyde
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Synthesis of 3,4-dimethoxy-5-hydroxybenzaldehyde (1) in three steps from vanillin with the key step being a copper catalyzed hydrolysis of 5- bromovanillin to give 4,5-dihydroxy-3-methoxybenzaldehyde.
- Ellis, James E.,Lenger, Steven R.
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- Catalytic oxidation of para-substituted phenols with nitrogen dioxide and oxygen
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A series of para-substituted phenols was oxidized to the corresponding benzoquinones in moderate to high yield with catalytic amounts of NO2 under O2 in MeOH. Little or no oxidation is observed under argon. Substrates of lower reactivity gave quinones when treated with stoichiometric amounts of NO2 in CCl4, but nitration of the aromatic ring became a significant side product.
- Bozell, Joseph J.,Hoberg, John O.,Dimmel, Donald R.
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- Structural changes of sinapic acid and sinapine bisulfate during autoclaving with respect to the development of colored substances
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Structural changes in sinapic acid during autoclaving were studied using spectral analysis, thin-layer chromatography, high-performance liquid chromatography, nuclear magnetic resonance (NMR), and mass spectroscopy. Color properties of sinapic acid and its derivatives were studied by determining the transmittance spectrum, calculating the Commission Internationale de l'Eclairage 1931 tristimulus values and converting to Hunter L a b values. It was found that the colorless sinapic acid aqueous solution (100 μg/mL) turned yellow after 15 min in an autoclave at 121 °C and 0.1 MPa. Filtering the yellow aqueous solution through a 0.45-μm filter removed a brown solid consisting of at least three undetermined colored substances and left a yellow liquid. A newly developed yellow substance, syringaldehyde, was identified in the liquid phase by comparing the NMR and mass spectra of the unknown with those of authentic syringaldehyde. Thomasidioic acid was also found in the liquid phase. Under the same autoclaving conditions, sinapine bisulfate showed no evidence of any structural or color changes.
- Cai,Arntfield,Charlton
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- Biotransformation of sinapic acid by the green algae Stichococcus bacillaris 155LTAP and Ankistrodesmus braunii C202.7a
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Sinapic acid was bioconverted by the green alga Stichococcus bacillaris into 4-hydroxy-3,5-dimethoxybenzoic acid, 4-hydroxy-3,5-dimethoxybenzaldehyde and 4-hydroxy-3,5-dimethoxybenzylic alcohol. Incubation of sinapic acid in a culture of the alga Ankistrodesmus braunii gave 3,6-dihydroxy-2,4-dimethoxy-7H-benzocyclohepten-7-one, a new compound formed by bioconversion of thomasidioic acid, the primary oxidative product of sinapic acid.
- DellaGreca, Marina,Pinto, Gabriele,Pollio, Antonino,Previtera, Lucio,Temussi, Fabio
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- Steric effects of bulky tethered arylpiperazines on the reactivity of Co-Schiff base oxidation catalysts—a synthetic and computational study
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New C2-symmetric and C2-asymmetric Co-Schiff base catalysts tethered to arylpiperazine units were synthesized and used to oxidize phenolic lignin models to para-benzoquinones. Synthetic approaches to these catalysts were optimized to include fewer steps and broaden the types of catalyst structures available. In contrast to conventional Co-Schiff base catalysts, these systems induce phenolic oxidation in the absence of an external axial base, simplifying the process. Asymmetric catalysts bearing a phenylethylene or diphenylmethyl piperazine substituent display the highest catalytic activity observed to date for the conversion of S-models to 2,6-dimethoxybenzoquinone (DMBQ). Computational analysis shows that more reactive catalysts populate conformations that favor oxidation in preference to non-productive decomposition routes. This balance between catalyst reactivity and catalyst deactivation is optimized by inclusion of sufficient steric bulk around the periphery of the Schiff base ligand, reducing catalyst deactivation and allowing oxidations to proceed in the absence of an added axial ligand.
- Key, Rebecca E.,Elder, Thomas,Bozell, Joseph J.
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- Initial steps of the peroxidase-catalyzed polymerization of coniferyl alcohol and/or sinapyl aldehyde: Capillary zone electrophoresis study of pH effect
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Capillary zone electrophoresis has been used to monitor the first steps of the dehydrogenative polymerization of coniferyl alcohol, sinapyl aldehyde, or a mixture of both, catalyzed by the horseradish peroxidase (HRP)-H2O2 system. When coniferyl alcohol was the unique HRP substrate, three major dimers were observed (β-5, β-β, and β-O-4 interunit linkages) and their initial formation velocity as well as their relative abundance varied with pH. The β-O-4 interunit linkage was thus slightly favored at lower pH values. In contrast, sinapyl aldehyde turned out to be a very poor substrate for HRP except in basic conditions (pH 8). The major dimer observed was the β,β′-di-sinapyl aldehyde, a red-brown exhibiting compound which might partly participate in the red coloration usually observed in cinnamyl alcohol dehydrogenase-deficient angiosperms. Finally, when a mixture of coniferyl alcohol and sinapyl aldehyde was used, it looked as if sinapyl aldehyde became a very good substrate for HRP. Indeed, coniferyl alcohol turned out to serve as a redox mediator (i.e. shuttle oxidant ) for the sinapyl aldehyde incorporation in the lignin-like polymer. This means that in particular conditions the specificity of oxidative enzymes might not hinder the incorporation of poor substrates into the growing lignin polymer.
- Fournand, David,Cathala, Bernard,Lapierre, Catherine
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- Comparison of structure in solid state of new 1,5-bis(4-cyano-2,6-dimethoxyphenoxy)alkanes by means of 13C CP/MAS NMR and X-ray diffraction
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The synthesis and structural studies in solid state of new 1,5-bis(4-cyano-2,6-dimethoxyphenoxy)-3-oxapentane 1 and 1,5-bis(4-cyano-2,6-methoxyphenoxy)pentane 2 are presented. The observed complicated network of intermolecular interaction with participation of nitrile groups could play a role in their interaction with the biological target. In vitro screen against 60 human tumor cell lines revealed that compound 1 has promising growth inhibitory power GI50 against SR (leukemia) and HOP-92 (non-small lung cancer) equal to 4.33×10-6 and 1.03×10-5 M, respectively.
- Zabiński, Jerzy,Wolska, Irena,Maciejewska, Dorota
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- Aerobic oxidation of syringyl alcohol over N-doped carbon nanotubes
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Carbon nanotubes (CNTs) doped with nitrogen were prepared using two methodologies, chemical vapor deposition (N-CNTs) and post-modification (N-CNTs-P), and characterized by N2 adsorption, TEM, XPS, Raman spectroscopy, and water capacity measurements. Their catalytic performance was assessed for aerobic oxidation of syringyl alcohol, a model of syringyl unit of lignin. With N-CNTs, the reaction readily proceeds under mild conditions (40–80 °C, 1 atm of air, isopropanol, ethanol, or water as solvents), leading to syringaldehyde with 95–97% yield. A correlation between N content in N-CNTs and oxidation rate has been established. Spectroscopic studies coupled with water capacity measurements implicated that a blend of graphitic and pyridinic nitrogen species is crucial for catalytic activity. The catalysts can be easily recovered, regenerated, and reused without significant loss of the catalytic performance. N-CNTs-P catalysts, which endow high content of quinone-type oxygen groups, provide significantly lower syringaldehyde yield due to fast deactivation.
- Kholdeeva, Oxana A.,Kibis, Lidiya S.,Podyacheva, Olga Yu.,Suboch, Arina N.,Zalomaeva, Olga V.
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- Mild selective oxidative cleavage of lignin C-C bonds over a copper catalyst in water
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The conversion of lignin into aromatics as commodity chemicals and high-quality fuels is a highly desirable goal for biorefineries. However, the presence of robust inter-unit carbon-carbon (C-C) bonds in natural lignin seriously impedes this process. Herein, for the first time, we report the selective cleavage of C-C bonds in β-O-4 and β-1 linkages catalyzed by cheap copper and a base to yield aromatic acids and phenols in excellent yields in water at 30 °C under air without the need for additional complex ligands. Isotope-labeling experiments show that a base-mediated Cβ-H bond cleavage is the rate-determining step for Cα-Cβ bond cleavage. Density functional theory (DFT) calculations suggest that the oxidation of β-O-4 ketone to a key intermediate, i.e., a peroxide, by copper and O2 lowers the Cα-Cβ bond dissociation energy and facilitates its subsequent cleavage. In addition, the catalytic system could be successfully applied to the depolymerization of various authentic lignin feedstocks, affording excellent yields of aromatic compounds and high selectivity of a single monomer. This study offers the potential to economically produce aromatic chemicals from biomass.
- Hu, Yuzhen,Li, Song,Ma, Longlong,Wang, Chenguang,Yan, Long,Zhang, Qi,Zhang, Xinghua,Zhao, Xuelai
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p. 7030 - 7040
(2021/09/28)
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- Profiling of the formation of lignin-derived monomers and dimers from: Eucalyptus alkali lignin
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Lignin is a renewable and the most abundant aromatic source that can be used for extensive chemicals and materials. Although approximately 50 million tons of lignin are produced annually as a by-product of the pulp and paper industry, it is currently underutilized. It is important to know the structural features of technical lignin when considering its application. In this work, we have demonstrated the formation of low-molecular-weight constituents from hardwood (Eucalyptus) lignin, which produces much more low-molecular-weight constituents than softwood (spruce) lignin, after a chemical pulping process, and analyzed the micromolecular compositions in the alkali lignin after fractionation by dichloromethane (DCM) extraction. By applying analytical methods (gel-permeation chromatography, 2D NMR and GC-MS) with the aid of evidence from authenticated compounds, a great treasure trove of lignin-derived phenolic compounds from Eucalyptus alkali lignin were disclosed. Except for some common monomeric products, as many as 15 new lignin-derived monomers and dimers including syringaglycerol, diarylmethane, 1,2-diarylethanes, 1,2-diarylethenes, (arylvinyl ether)-linked arylglycerol dimers and isomeric syringaresinols were identified in the DCM-soluble fraction. Regarding the formation and evolution of the Cα-condensed β-aryl ether structure, a novel route that is potentially responsible for the high content of β-1 diarylethenes and diarylethanes in the lignin low-molecular-weight fraction, in addition to the β-1 (spirodienone) pathway, was proposed. This work not only provides novel insights into the chemical transformation of S-G lignin during the alkali pulping process, but also discovered lignin-derived phenolic monomers and dimers that can potentially be used as raw materials in the chemical or pharmaceutical industries. This journal is
- Hu, Zhenhua,Li, Suxiang,Lu, Fachuang,Shi, Lanlan,Wang, Chen,Yue, Fengxia,Zhang, Han,Zhao, Chengke
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supporting information
p. 7366 - 7375
(2020/11/18)
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- Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment
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Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry.
- Cheng, Xi-Chuang,Guo, Xin-Ran,Liu, Hua-Min,Liu, Yu-Lan,Qin, Zhao,Wang, Xue-De
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p. 4348 - 4358
(2020/09/22)
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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 continuously preparing vanillin and syringaldehyde
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The invention relates to the technical field of organic synthesis, in particular to a method for continuously preparing vanillin and syringaldehyde. According to the method for continuously preparingthe vanillin and the syringaldehyde, the vanillin and the syringaldehyde are continuously synthesized and produced by taking the p-hydroxy benzaldehyde as the raw material, and the vanillin and the syringaldehyde are obtained by directly etherifying brominated products without refining in the process, so that the aims of shortening the process, improving the yield, reducing the cost, being safe and environment-friendly and easily realizing industrial production are achieved.
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Paragraph 0023-0031; 0035; 0036; 0037
(2020/01/08)
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- Method for synthesizing nitrogen-containing aromatic compound through one-step photocatalytic lignin depolymerization and amination (by machine translation)
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The invention discloses a method, synthesizing a nitrogen-containing aromatic compound through one-step photocatalytic lignin depolymerization and amination. Belong to lignin application technical field. To the invention, lignin or a model compound thereof is dissolved in a solvent, and under the excitation, photo-catalyst catalysis, the auxiliary and nitrogen source react 6~24 hours at room temperature, C-C bond is selectively cracked and aminated to synthesize nitrogen-containing aromatic compound; lignin or a model compound, photocatalyst, auxiliary, nitrogen source molar ratio 100: (1~20): (1~100): 100. The C-C bond disclosed by the invention is simple, mild, high, selective and high, 100% and can continuously feed, has a good degradation effect on natural lignin, and can further react with the hydrazine product to obtain the nitrogen heterocyclic compound, and the like, and has the advantages. (by machine translation)
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Paragraph 0064-0070
(2019/09/13)
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- Magnetic nano-structured cobalt-cobalt oxide/nitrogen-doped carbon material as an efficient catalyst for aerobic oxidation of p-cresols
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Efficient aerobic oxidation has been developed for the selective preparation of a sequence of valuable p-hydroxybenzaldehydes from corresponding p-cresols, using a new magnetically separable catalyst of nano-structured cobalt-cobalt oxide/nitrogen-doped carbon (CoOx@CN) material. CoOx@CN showed high activity for the 2-methoxy-4-cresol oxidation to vanillin, giving great yield (90%) and with good turnover number (210), as well as other p-cresols in good to great yields. The catalytic performance was investigated and related to the structural, chemical and magnetic properties which determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The effects of base to substrate molar ratio, catalyst concentration, temperature, and solvent on the conversion and selectivity patterns also have been studied. The investigation revealed that remarkable catalytic properties of CoOx@CN could be ascribed to the active species cobalt oxide, doped nitrogen and porous carbon with large surface area. The size of the catalyst is a key factor for catalyst performance. The ferromagnetic property of catalyst enables to recycle easily by an external magnetic field and reuse six successive times without significant activity loss.
- Liang, Cheng,Li, Xuefeng,Su, Diefeng,Ma, Qiyi,Mao, Jianyong,Chen, Zhirong,Wang, Yong,Yao, Jia,Li, Haoran
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p. 121 - 131
(2018/05/22)
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- Synthesis of CoFeO mixed oxides via an alginate gelation process as efficient heterogeneous catalysts for lignin depolymerization in water
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A catalytic oxidative fragmentation of a lignin dimer and polymer extracted from wheat straw was successfully performed under eco-friendly conditions: 10% O2/N2 as the oxidizing agent, water as the solvent (pH ≈ 7), and Co3O4, Fe2O3 and CoFeO mixed oxides as heterogeneous catalysts and at temperatures of T = 150 °C and 200 °C. These catalysts unexpectedly showed tunable selectivity that directly depends on the composition of the selected bimetallic nanoparticles. High selectivity for benzoic acid and alkylbenzene (above 50%) was observed over Co50-Fe50 at 200 °C. Under similar conditions, the conversion of wheat organosolv lignin over Co50-Fe50 at 150 °C for 4 h yielded up to 50 wt% of monomeric species (based on dry lignin) and up to 19% of aromatic molecules with high selectivity to aromatic aldehydes (syringaldehyde and vanillin), up to 60%. An important fraction of water-soluble oligomers, with low molecular weights, was also formed during the catalytic treatment. The oxide nanomaterials were readily separated from the residual lignin during the recyclability test. The yield and the product distribution can be tuned by choosing the oxidation parameters: temperature, reaction time, oxygen partial pressure, solvent and catalyst charges.
- Hdidou,Khallouk,Solhy,Manoun,Oukarroum,Barakat
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p. 5445 - 5453
(2018/11/20)
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- Revisiting alkaline aerobic lignin oxidation
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Lignin conversion to renewable chemicals is a promising means to improve the economic viability of lignocellulosic biorefineries. Alkaline aerobic oxidation of lignin has long been employed for production of aromatic compounds such as vanillin and syringaldehyde, but this approach primarily focuses on condensed substrates such as Kraft lignin and lignosulfonates. Conversely, emerging lignocellulosic biorefinery schemes enable the production of more native-like, reactive lignin. Here, we revisit alkaline aerobic oxidation of highly reactive lignin substrates to understand the impact of reaction conditions and catalyst choice on product yield and distribution. The oxidation of native poplar lignin was studied as a function of temperature, NaOH loading, reaction time, and oxygen partial pressure. Besides vanillin and syringaldehyde, other oxidation products include acetosyringone and vanillic, syringic, and p-hydroxybenzoic acids. Reactions with vanillin and syringaldehyde indicated that these compounds are further oxidized to non-aromatic carboxylic acids during alkaline aerobic oxidation, with syringaldehyde being substantially more reactive than vanillin. The production of phenolic compounds from lignin is favored by high NaOH loadings and temperatures, but short reaction times, as the products degrade rapidly, which is further exacerbated by the presence of oxygen. Under optimal conditions, a phenolic monomer yield of 30 wt% was obtained from poplar lignin. Testing a range of catalysts showed that Cu-containing catalysts, such as CuSO4 and LaMn0.8Cu0.2O3, accelerate product formation; specifically, the catalyst does not increase the maximum yield, but expands the operating window in which high product yields are obtainable. We also demonstrate that other native and isolated lignin substrates that are significantly chemically modified are effectively converted to phenolic compounds. Finally, alkaline aerobic oxidation of native lignins was compared to nitrobenzene oxidation and reductive catalytic fractionation, as these methods constitute suitable benchmarks for lignin depolymerization. While nitrobenzene oxidation achieved a somewhat higher yield, similar monomer yields were obtained through RCF and alkaline aerobic oxidation, especially for lignins with a high guaiacyl- and/or p-hydroxyphenyl-content, as syringyl units are more unstable during oxidation. Overall, this study highlights the potential for aerobic lignin oxidation revisited on native-like lignin substrates.
- Schutyser, Wouter,Kruger, Jacob S.,Robinson, Allison M.,Katahira, Rui,Brandner, David G.,Cleveland, Nicholas S.,Mittal, Ashutosh,Peterson, Darren J.,Meilan, Richard,Román-Leshkov, Yuriy,Beckham, Gregg T.
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supporting information
p. 3828 - 3844
(2018/08/21)
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- Highly Efficient Oxidation of Amines to Aldehydes with Flow-based Biocatalysis
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A new mild and efficient process for the aqueous preparation of aldehydes, which are employed as flavour and fragrance components in food, beverage, cosmetics, as well as in pharmaceuticals, was developed using a continuous-flow approach based on an immobilised pure transaminase-packed bed reactor. HEWT, an ω-transaminase from the haloadapted bacterium Halomonas elongata, has been selected for its excellent stability and substrate scope. Sixteen different amines were rapidly (3–15 min) oxidised to the corresponding aldehydes (90 to 99 %) with only 1 to 5 equivalents of sodium pyruvate. The process was fully automated, allowing for the in-line recovery of the pure aldehydes (chemical purity >99 % and isolated yields above 80 %), without any further work-up procedure.
- Contente, Martina L.,Dall'Oglio, Federica,Tamborini, Lucia,Molinari, Francesco,Paradisi, Francesca
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p. 3843 - 3848
(2017/09/25)
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- A rapid, solvent-free deprotection of methoxymethyl (MOM) ethers by pTSA; An eco-friendly approach
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Background: Ease of preparation and alkaline stability of methoxymethyl (MOM) makes it an important hydroxyl protecting group. A number of methods are available for the deprotection of MOM. Though the methods are good in general, they use solvents, require prolonged reaction time and tedious work up. A solvent free, solid phase, fast deprotection of MOM has been developed and is the major theme of this paper. Methods: A mixture of MOM protected compounds and pTSA is triturated in a mortar (5 min) and left at room temperature for 30 min. On addition of water (4°C), pTSA, methanol and formaldehyde dissolved leaving the products as precipitates. Results: A series of different MOM ethers were deprotected by this method in good to excellent yield (85-98%). The compatibility of MOM in the presence of other protections such as methoxyl, benzyl, ester, amide, allyl and lactone was also established. Acetate protection is not stable under these conditions. Conclusion: An efficient, selective and high yielding deprotection MOM groups by pTSA under solvent free condition is described. The process is environment friendly since no solvent was used in the deprotection process. The reaction conditions are mild and should be useful for the deprotection of MOM derivatives of complex and labile molecules.
- Pandurangan, Nanjan
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p. 231 - 235
(2017/07/15)
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- Photocatalytic Oxidation of Lignin Model Systems by Merging Visible-Light Photoredox and Palladium Catalysis
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Lignin valorization has long been recognized as a sustainable solution for the renewable production of aromatic compounds. Two-step oxidation/reduction strategies, whereby the first oxidation step is required to "activate" lignin systems for controlled fragmentation reactions, have recently emerged as viable routes toward this goal. Herein we describe a catalytic protocol for oxidation of lignin model systems by combining photoredox and Pd catalysis. The developed dual catalytic protocol allowed the efficient oxidation of lignin model substrates at room temperature to afford the oxidized products in good to excellent yields.
- K?rk?s, Markus D.,Bosque, Irene,Matsuura, Bryan S.,Stephenson, Corey R. J.
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supporting information
p. 5166 - 5169
(2016/10/14)
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- A ligand-free, powerful, and practical method for methoxylation of unactivated aryl bromides by use of the CuCl/HCOOMe/MeONa/MeOH system
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A ligand-free, powerful, and practical method for mono and polymethoxylation of unactivated aryl bromides has been developed; CuCl was used as catalyst, HCOOMe as cocatalyst, and methanolic MeONa as both nucleophile and solvent. This eco-friendly procedure is characterized by operational simplicity, inexpensive substrates (unactivated mono to polybromoarenes), full conversion, and direct recovery of pure MeOH.
- Guo, Ying,Ji, Si-Zhe,Chen, Cheng,Liu, Hong-Wei,Zhao, Jian-Hong,Zheng, Yu-Lin,Ji, Ya-Fei
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p. 8651 - 8664
(2015/03/05)
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- The method of preparing the aromatic hydroxy substituted aminoaldehyde
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The present invention accordingly provides a process for preparing aldehydes of the formula (I) in which one, two or all three radicals of the group R1, R3 and R5 denote hydroxyl, and the radical or radicals of the group R1, R3 and R5 that do not denote hydroxyl are, independently of one another, hydrogen, C1-C8 alkyl or C6-C14 aryl, and R2 and R4 independently of one another are hydrogen, C1-C8 alkyl, C1-C8 alkoxy or C6-C14 aryl, the process being characterized in that an aldehyde of the formula (II) in which one, two or all three radicals of the group R'1, R'3 and R'5 denote C1-C8 alkoxy, and the radical or radicals of the group R'1, R'3 and R'5 that do not denote C1-C8 alkoxy are, independently of one another, hydrogen, C1-C8 alkyl or C6-C14 aryl, and R2 and R4 have the definitions indicated under formula (I), is reacted at elevated temperature and elevated pressure in the presence of (C1-C4 alkyl)2-amine, and the reaction product of the formula (I) is subsequently isolated.
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Paragraph 0048
(2016/10/17)
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- Catalytic oxidation of lignin-acetoderivatives: A potential new recovery route for value-added aromatic aldehydes from acetoderivatives
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Catalytic wet air oxidation (CWAO) of lignin and phenolic composition of wastewater is a useful pathway towards the recovery of valuable compounds. In this study, bamboo lignin was catalytically oxidized to aromatic aldehydes and acetoderivatives; similarly acetovanillone and acetosyringone were oxidized to vanillin and syringaldehyde, respectively. A total product yield of 9.5% from bamboo lignin and a vanillin yield of 51% with greater than 90% selectivity from acetovanillone were achieved. The proposed reaction pathways suggest a two-step route towards the formation of value-added aromatic aldehydes from lignin via degradation of acetoderivatives. The kinetics study for the degradation of acetovanillone and formation of vanillin was reported for the first time in the temperature range of 120-150°C, with activation energies of 85.29 kJ mol-1 and 120.7 kJ mol-1, respectively. To date, CWAO breaks down the lignin polymer and toxic phenolic compounds reasonably and effectively, producing value-added aldehydes, which could become a potential new route for the recovery of value-added products.
- Alunga, Kissa R.,Ye, Yue-Yuan,Li, Shui-Rong,Wang, Duo,Liu, Yun-Quan
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p. 3746 - 3753
(2015/06/30)
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- New synthesis of vanillin by degradation of lignin in presence of functional basic ionic liquid
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The degradation of lignin catalyzed by functional basic ionic liquid was investigated. Higher conversion of lignin and simpler degradation product composition were obtained in the presence of basic ionic liquid, comparing with that under traditional NaOH
- Yi, Fengping,Jiang, Xiaoyan,Niu, Jihua,Zhang, Lirong,Wang, Zhen
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p. 885 - 888
(2015/02/05)
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- Cu(OAc)2-catalyzed remote benzylic C(sp3)-H oxyfunctionalization for C=O formation directed by the hindered para-hydroxyl group with ambient air as the terminal oxidant under ligand- and additive-free conditions
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A hindered para-hydroxyl group-directed remote benzylic C(sp3)-H oxyfunctionalization has been developed for the straightforward transformation of 2,6-disubstituted 4-cresols, 4-alkylphenols, 4-hydroxybenzyl alcohols and 4-hydroxybenzyl alkyl ethers into various aromatic carbonyl compounds. The ligand- and additive-free Cu(OAc)2-catalyzed atmospheric oxidation mediated by ethylene glycol unlocks a facile, atom-economical, and environmentally benign C=O formation for the functionalization of primary and secondary benzyl groups. Due to the pharmaceutical importance of 4-hydroxybenzaldehydes and 4-hydroxyphenones, the methodology is expected to be of significant value for both fundamental research and practical applications.
- Jiang, Jian-An,Chen, Cheng,Huang, Jian-Gang,Liu, Hong-Wei,Cao, Song,Ji, Ya-Fei
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supporting information
p. 1248 - 1254
(2014/03/21)
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- Efficient Co(OAc)2-catalyzed aerobic oxidation of EWG-substituted 4-cresols to access 4-hydroxybenzaldehydes
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We reported an efficient ligand-free Co(OAc)2·4H 2O/NaOH/O2/ethylene glycol reaction system that enables selective aerobic oxidation of a wide range of substrates covering 2,6-di-EWG-, 2,3,6-tri-EWG-, 2-EWG-, and 2-EWG-6-EDG-substituted 4-cresols into the corresponding 4-hydroxybenzaldehydes. Based on the experimental investigations and well-defined p-benzoquinone methides, a plausible reaction mechanism was proposed. Considering the simplicity of the procedure and importance of the products, the methodology was expected to become a favorable and practical tool in related benzylic C(sp3)-H functionalization chemistry.
- Jiang, Jian-An,Du, Jia-Lei,Liao, Dao-Hua,Wang, Zhan-Guo,Ji, Ya-Fei
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supporting information
p. 1406 - 1411
(2014/03/21)
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- Environmentally friendly and highly efficient Co(OAc)2-catalyzed aerobic oxidation to access 2,6-di-electron-donating group substituted 4-hydroxybenzaldehydes
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A highly efficient and green aerobic oxidation has been developed for selectively preparing a series of valuable 2,6-dialkyl-, dialkoxyl-, and alkoxylalkyl-substituted 4-hydroxybenzaldehydes from corresponding 4-cresols in good to excellent yields, using a catalytic system of Co(OAc)24H2O (1.0 mol%)-NaOH (1.0 equiv)-O2(1.0 atm) in aqueous ethylene glycol (EG/H2O = 20/1, v/v) at 50 °C. Furthermore, a plausible mechanism was proposed for the direct oxyfunctionalization of the aromatic methyl group into the aldehyde group.
- Jiang, Jian-An,Du, Jia-Lei,Zhang, Zhong-Nan,Zhai, Jiao-Jiao,Ji, Ya-Fei
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p. 1430 - 1440
(2016/09/23)
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- Steric effects in the design of Co-Schiff base complexes for the catalytic oxidation of lignin models to para-benzoquinones
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New Co-Schiff base complexes that incorporate a sterically hindered ligand and an intramolecular bulky piperazine base in close proximity to the Co center are synthesized. Their utility as catalysts for the oxidation of para-substituted lignin model phenols with molecular oxygen is examined. Syringyl and guaiacyl alcohol, as models of S and G units in lignin, are oxidized in good yield using a catalyst bearing an N-benzylpiperazinyl substituent, with the catalysts displaying improved reactivity for G oxidation. Computational evaluation of the catalysts shows that the piperazinyl substituent is within bonding distance of the Co center. The increased steric interference is suggested as the source of increased G reactivity. This journal is the Partner Organisations 2014.
- Biannic, Berenger,Bozell, Joseph J.,Elder, Thomas
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supporting information
p. 3635 - 3642
(2014/07/08)
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- An effective strategy to develop active cinnamic acid-directed antioxidants based on elongating the conjugated chains
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To optimize antioxidant activity and lipophilicity of cinnamic acid derivatives (CAs) including ferulic acid, sinapic acid, 3,4-dimethoxycinnamic acid, and p-hydroxycinnamic acid, four analogs bearing an additional double bond between their aromatic ring and propenoic acid moiety were designed and synthesized based on the conjugated chain elongation strategy. The antioxidant performance of the CAs were investigated by 2,2′-diphenyl-1-picrylhydrazyl (DPPH)-scavenging, ferric reducing/antioxidant power, cyclic voltammetry, DNA strand breakage-inhibiting and anti-haemolysis activity assays. It was found that CAs with elongation of conjugated chains display increased DPPH --scavenging, DNA strand breakage-inhibiting and anti-haemolysis activities as compared to their parent molecules, due to their improved hydrogen atom-donating ability and lipophilicity. Overall, this work highlights an effective strategy to develop potential CA-directed antioxidants by elongating their conjugated chain.
- Li, Yan,Dai, Fang,Jin, Xiao-Ling,Ma, Meng-Meng,Wang, Yi-Hua,Ren, Xiao-Rong,Zhou, Bo
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- Practical Cu(OAc)2/TEMPO-catalyzed selective aerobic alcohol oxidation under ambient conditions in aqueous acetonitrile
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We reported a ligand-and additive-free Cu(OAc)2/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary and secondary benzylic alcohols, primary and secondary 1-heteroaryl alcohols, cinnamyl alcohols, and aliphatic alcohols to the corresponding aldehydes and ketones. This ambient temperature oxidation protocol is of practical features like aqueous acetonitrile as solvent, ambient air as the terminal oxidant, and low catalyst loading, presenting a potential value in terms of both economical and environmental considerations. Based on the experimental observations, a plausible reaction mechanism was proposed.
- Jiang, Jian-An,Du, Jia-Lei,Wang, Zhan-Guo,Zhang, Zhong-Nan,Xu, Xi,Zheng, Gan-Lin,Ji, Ya-Fei
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supporting information
p. 1677 - 1681
(2014/03/21)
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- Formic-acid-induced depolymerization of oxidized lignin to aromatics
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Lignin is a heterogeneous aromatic biopolymer that accounts for nearly 30% of the organic carbon on Earth and is one of the few renewable sources of aromatic chemicals. As the most recalcitrant of the three components of lignocellulosic biomass (cellulose, hemicellulose and lignin), lignin has been treated as a waste product in the pulp and paper industry, where it is burned to supply energy and recover pulping chemicals in the operation of paper mills. Extraction of higher value from lignin is increasingly recognized as being crucial to the economic viability of integrated biorefineries. Depolymerization is an important starting point for many lignin valorization strategies, because it could generate valuable aromatic chemicals and/or provide a source of low-molecular-mass feedstocks suitable for downstream processing. Commercial precedents show that certain types of lignin (lignosulphonates) may be converted into vanillin and other marketable products, but new technologies are needed to enhance the lignin value chain. The complex, irregular structure of lignin complicates chemical conversion efforts, and known depolymerization methods typically afford ill-defined products in low yields (that is, less than 10-20wt%). Here we describe a method for the depolymerization of oxidized lignin under mild conditions in aqueous formic acid that results in more than 60wt% yield of low-molecular-mass aromatics. We present the discovery of this facile C-O cleavage method, its application to aspen lignin depolymerization, and mechanistic insights into the reaction. The broader implications of these results for lignin conversion and biomass refining are also considered.
- Rahimi, Alireza,Ulbrich, Arne,Coon, Joshua J.,Stahl, Shannon S.
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p. 249 - 252
(2015/03/30)
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- Oxidation of model lignin compounds with peracetic acid under homogeneous catalysis with polyoxometalates
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Oxidation of lignin model compounds with peracetic acid using polyoxometalate manganesecontaining sodium vanadomolybdophosphate Na11[PMo6V5O39Mn(OH)] as a catalyst has been studied. The effect of pH, concentration and nature of the oxidized compound, concentration of the catalyst and peracetic acid, and temperature on kinetics of oxidation and the products composition has been investigated.
- Popova,Beloglazova,Bogolitsyn,Tortseva,Verkholomova,Pokryshkin
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p. 2092 - 2097
(2015/02/02)
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- Efficient cobalt-catalyzed oxidative conversion of lignin models to benzoquinones
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Phenolic lignin model monomers and dimers representing the primary substructural units of lignin were successfully oxidized to benzoquinones in high yield with molecular oxygen using new Co-Schiff base catalysts bearing a bulky heterocyclic nitrogen base as a substituent. This is the first example of a catalytic system able to convert both S and G lignin model phenols in high yield, a process necessary for effective use of lignin as a chemical feedstock.
- Biannic, Berenger,Bozell, Joseph J.
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supporting information
p. 2730 - 2733
(2013/07/26)
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- Aerobic oxidation of β-1 lignin model compounds with copper and oxovanadium catalysts
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The reactivity of homogeneous oxovanadium and copper catalysts toward aerobic oxidation of phenolic and nonphenolic β-1 lignin model compounds has been investigated. Aerobic oxidation of diastereomeric, nonphenolic β-1 lignin models (1T, 1E) using the six-coordinate vanadium complex (HQ) 2VV(O)(OiPr) (HQ = 8-oxyquinolinate) as a precatalyst in pyridine afforded ketone (3) and dehydrated ketone (4) derived from oxidation of the secondary alcohol. In contrast, using CuOTf/2,6-lutidine/ TEMPO (OTf = trifluoromethanesulfonate, TEMPO = 2,2,6,6-tetramethyl-piperidin-1- yl-oxyl) in toluene for the same reaction afforded 3,5-dimethoxybenzaldehyde (5) and 4-methoxybenzaldehyde (6) as major products resulting from C α-Cβ bond cleavage. Reactions of the corresponding phenolic lignin model compounds (2T, 2E) with 10 mol % CuOTf/2,6-lutidine/TEMPO gave ketone (9) as the major product, whereas 10 mol % (HQ)2VV(O)(OiPr) or a stoichiometric amount of CuOTf/2,6-lutidine/TEMPO yielded 2,6-dimethoxybenzoquinone (10) as the major product, arising from cleavage of the Caryl-Cα bond. Different selectivity was observed in the oxidation of 2T, 2E using the five-coordinate complex (dipic)VV(O)(OiPr) (dipic = dipicolinate), with α,β-unsaturated aldehyde (14) as the major product (formed from oxidation of the primary alcohol and dehydration). The key differences in chemoselectivity between the vanadium and copper catalysts in the oxidations of these phenolic and nonphenolic β-1 lignin models are discussed.
- Sedai, Baburam,Diaz-Urrutia, Christian,Baker, R. Tom,Wu, Ruilian,Silks, L. A. Pete,Hanson, Susan K.
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p. 3111 - 3122
(2014/01/06)
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- Process of lignin oxidation in an ionic liquid coupled with separation
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A novel approach has been developed in order to use lignin as a renewable resource for the production of a high added-value aromatic aldehyde. The concept is based on the use of an ionic liquid as a reversible medium coupled with the separation process, which prevents the aromatic aldehyde products from oxidizing and increases their yields. The conversion of lignin reached 100%, and the total yield of the aromatic aldehydes (vanillin, syringaldehyde and p-hydroxybenzaldehyde) was 29.7% in the coupled process. In addition, the mixture of product and IL phase was easily separated, and the IL phase demonstrated good reusability. Hence, a clean and environmentally friendly strategy for overall utilization of lignin and preparation of an aromatic aldehyde is developed.
- Liu, Shiwei,Shi, Zhongliang,Li, Lu,Yu, Shitao,Xie, Congxia,Song, Zhanqian
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p. 5789 - 5793
(2013/05/09)
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- Ferrocene tagged functional polymer: A robust solid-phase reagent for O-demethylation
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Ferrocene tagged functional polymer was synthesized by exploiting the propensity of the Merrifield resin to undergo quaternization with N-ferrocenylmethyl benzimidazole followed by subsequent anion metathesis reaction. The synthesized polymer when employed as a solid-phase reagent for O-demethylation of aryl methyl ethers, showed TON in the range of 7373-8930 and TOF in the range of 279-494 h-1.
- Kurane, Rajanikant,Gaikwad, Vipul,Jadhav, Jagannath,Salunkhe, Rajashri,Rashinkar, Gajanan
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p. 6361 - 6366,6
(2012/12/12)
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- Kinetics and mechanism of oxidation of syringic acid and 4-methoxycinnamic acid by dichromate in presence and absence of succinic acid
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The effect of varying concentration of [substrate], [oxidant], [H +], added neutral salt have been studied. It has been found that, the order of reaction with respect to [oxidant] and [substrate] found to be unity from the slope of plots log k vs log [sub]. The rate of reaction increases with decrease in pH of perchloric acid. Hammett's acidity function and activity of water have been studied. Effect of temperature has been studied. Activation parameters were computed. The plot of ΔH* vs ΔS* is linear. The effect of dielectric constant of the medium indicates the reaction to be +ve iondipole. The result of oxidation products have been identified.
- Kulkarni,Bongane,Gavali,Patel
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p. 1347 - 1350
(2013/02/22)
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- A concise synthesis of viscolin, and its anti-inflammatory effects through the suppression of iNOS, COX-2, ERK phosphorylation and proinflammatory cytokines expressions
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In the present report, a concise synthesis of viscolin (1) has been achieved. The anti-inflammatory effect of viscolin was investigated in vitro and in vivo. Viscolin blocked the expression of iNOS and COX-2, and it also inhibited the ERK for the activation of NF-κB in LPS-stimulated RAW 264.7 macrophages. Western blotting and immunohistochemical analysis revealed that viscolin decreased Carr-induced iNOS and COX-2 expressions. These results could help to deduce the anti-inflammatory mechanisms.
- Huang, Guan-Jhong,Bhaskar Reddy, M. Vijaya,Kuo, Ping-Chung,Huang, Chieh-Hung,Shih, Hung-Cheng,Lee, E.-Jian,Yang, Mei-Lin,Leu, Yann-Lii,Wu, Tian-Shung
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p. 371 - 378
(2012/03/26)
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- PROCESS FOR PREPARING HYDROXY-SUBSTITUTED AROMATIC ALDEHYDES
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The present invention therefore relates to a process for preparing an aldehyde of the formula (I) where one, two or all three radicals from the group of R1, R3 and R5 are hydroxyl, and that radical or those radicals from the group of R1, R3 and R5 which are not hydroxyl are each independently hydrogen, C1-C8-alkyl or C6-C14-aryl, and R2 and R4 are each independently hydrogen, C1-C8-alkyl, C1-C8-alkoxy or C6-C14-aryl, which comprises converting an aldehyde of the formula (II) in which one, two or all three radicals from the group of R′1, R′3 and R′5 are C1-C8-alkoxy, and that radical or those radicals from the group of R′1, R′3 and R′5 which are not C1-C8-alkoxy are each independently hydrogen, C1-C8-alkyl or C6-C14-aryl, and R2 and R4 are each as defined for formula (I), at elevated temperature and elevated pressure in the presence of (C1-C4-alkyl)2-amine, and then isolating the reaction product of the formula (I).
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Page/Page column 4
(2011/10/13)
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- Synthesis of (1R,2S)-2-(4'-allyl-2',6'-dimethoxyphenoxyl)-1-(4''-hydroxy- 3'', 5''-dimethoxyphenyl)propan-1-ol
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The asymmetric synthesis of the natural neolignan (1R,2S)-2-(4'-allyl-2', 6'-dimethoxyphenoxyl)-1-(4''-hydroxy-3'',5''- dimethoxyphenyl)propan-1-ol based on an asymmetric dihydroxylation as a key reaction using AD-mix-β to preparing the chiral threo-(1R,2R)-glycerol. The reaction, threo-alcohols were inverted by an SN2 reaction into erythro-(1R,2S)-isomers.
- Ding, Junwei,Qi, Rongwei,Zhou, Haitang,Jiao, Bin,Xia, Yamu
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experimental part
p. 519 - 521
(2011/11/29)
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- Synthesis and antioxidant evaluation of novel 4-aryl-hexahydroquinolines from lignin
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A series of 4-aryl-hexahydroquinolines were prepared by Hantzsch reaction using aromatic aldehydes obtained from lignin, 1,3-cyclohexanediones, β-ketoesters and ammonium carbonate. The antioxidant properties of compounds 5a-c and 5g-i were evaluated by two methods: scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and scavenging effect on 2,2′-azino-bis(3-ethylenzothiazoline-sulfonic acid) diammonium salt (ABTS+) radical. The results show that the compounds containing a methoxy moiety exhibit good activities. The study suggests that some synthesized compounds may serve as promising leads for the treatment against tumors or other free radical-related diseases.
- Yang, Xiao-Hui,Zhang, Ping-Hu,Zhou, Yong-Hong,Liu, Cheng-Guo,Lin, Xiao-Yu,Cui, Jing-Fang
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body text
p. 327 - 337
(2011/12/15)
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- An expeditious synthesis of syringaldehyde from para-cresol
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Syringaldehyde is prepared from p-cresol via a three step reaction sequence in overall yield of 63-67%. The synthesis involves selective bromination followed by high pressure and temperature methoxilation and catalytical oxidation. The use of copper chloride in different oxidation state as a catalyst in two key steps i.e. methoxilation in aromatic ring (by cuprous chloride) and oxidation of aromatic methyl to aldehyde (by cupric chloride) underscore fidelity of the process.
- Tripathi,Sama,Taneja
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experimental part
p. 379 - 381
(2010/10/18)
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- Oxidative depolymerization of lignin in ionic liquids
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Beech lignin was oxidatively cleaved in ionic liquids to give phenols, unsaturated propylaromatics, and aromatic aldehydes. A multiparallel batch reactor system was used to screen different ionic liquids and metal catalysts. Mn(NO3)2 in 1-ethyl-3-methylimidazolium trifluoromethanesulfonate [EMIM][CF3SO3] proved to be the most effective reaction system. A larger scale batch reaction with this system in a 300mL autoclave (11g lignin starting material) resulted in a maximum conversion of 66.3% (24h at 100 °C, 84 × 105 Pa air). By adjusting the reaction conditions and catalyst loading, the selectivity of the process could be shifted from syringaldehyde as the predominant product to 2,6-dimethoxy-1,4-benzoquinone (DMBQ). Surprisingly, the latter could be isolated as a pure substance in 11.5 wt% overall yield by a simple extraction/crystallization process.
- St?rk, Kerstin,Taccardi, Nicola,B?smann, Andreas,Wasserscheid, Peter
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experimental part
p. 719 - 723
(2011/12/21)
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- A continuous, quantitative fluorescent assay for plant caffeic acid o-methyltransferases
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Plant caffeic acid O-methyltransferases (COMTs) use S-adenosylmethionine (ado-met), as a methyl donor to transmethylate their preferred (phenolic) substrates in vivo, and will generally utilize a range of phenolic compounds in vitro. Collazo et al. (Anal. Biochem. 2005, 342, 86-92) have published a discrete, end-point fluorescence assay to detect histone methyltransferases using S-adenosyl homocysteine hydrolase and adeonsine deaminase as coupling enzymes and a thiol-specific fluorophore, Thioglo1, as the detecting reagent. Using this previous assay as a guide, we have developed and validated a facile, sensitive and real-time fluorescence assay for characterizing plant COMTs and in the process simplified the original assay as well by obviating the need for adenosine deaminase in the assay, and simultaneously converting an end-point assay into a continuous one. Our assay has been used to kinetically characterize recombinant sorghum COMT (Bmr-12) a key enzyme involved in cell wall lignification, and analyze COMT activity in maturing tillers from switchgrass plants. Data indicated that the calculated Km and Vmax values for the recombinant sorghum COMT using different substrates in the fluorescent assay were similar to published values for COMT enzymes from other plant species. Native COMT activity was greatest in internodes at the top of a tiller and declined in the more basal internodes. This new assay should have broad applicability for characterizing COMTs and potentially other plant methlytransferases that utilize ado-met as a methyl donor. This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society.
- Palmer, Nathan A.,Sattler, Scott E.,Saathoff, Aaron J.,Sarath, Gautam
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experimental part
p. 5220 - 5226
(2011/08/05)
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- METHOD FOR THE BREAKDOWN OF LIGNIN
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The invention describes a method for the direct production of molecules with a minimum molecular weight of 78 g/mol by the breakdown of lignin, lignin derivatives, lignin fragments, and/or lignin-containing substances or mixtures in the presence of at least one polyoxometallate and preferably in the presence of a radical scavenger in a liquid medium.
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Page/Page column 5-8
(2010/06/11)
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- On the reactions of two fungal laceases differing in their redox potential with lignin model compounds: products and their rate of formation
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Laceases (EC 1.10.3.2) are multicopper oxidases able to oxidize phenolic compounds such as lignin-related polyphenols. Since the discovery that so-called mediators effectively extend the family of lacease substrates, direct interactions between lignin-like materials and lacease have gained much less attention. In this work, the aim was to characterize oxidation products formed in direct laccase-catalyzed oxidation of different guaiacylic and syringylic lignin model compounds with two different laceases: a low redox potential Melanocarpus alborneces lacease and a high redox potential Trametes hirsuta lacease. By following the formation of different, mainly biphenylic (5-5) and benzylic oxidation products, it was found that although both of these enzymes generated practically the same pattern of products with particular types of syringyl and guaiacyl compounds, in some cases a clear difference in the rates of their formation was observed. The results also confirm further to the suggestions that syringylic compounds are able to act as mediators in their own oxidation reactions and also that in some instances acetylation of phenolic material may produce altered, unexpected structures.
- Maarit, Lahtinen,Kristiina, Kruus,Petri, Heinonen,Jussi, Sipilae
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experimental part
p. 8357 - 8365
(2010/08/19)
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- Development of synthetic methodology suitable for the radiosynthesis of combretastatin A-1 (CA1) and its corresponding prodrug CA1P
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Synthetic methodology has been established suitable for the preparation of combretastatin A-1 (CA1) and its corresponding phosphate prodrug salt (CA1P) in high specific activity radiolabeled form. Judicious selection of appropriate phenolic protecting groups to distinguish positions on the A-ring from the B-ring of the stilbenoid was paramount for the success of this project. Methylation of the C-4' phenolic moiety by removal of the tert- butyldimethylsilyl protecting group in the presence of methyl iodide was accomplished in excellent yield without significant Z to E isomerization. This step (carried out with 12C-methyl iodide as proof of concept in this study) represents the process in which a 14C radioisotope could be incorporated in an actual radiosynthesis. CA1 is a natural product isolated from the African bush willow tree (Combretum caffrum) that has important medicinal value due, in part, to its ability to inhibit tubulin assembly. As a prodrug, CA1P (OXi4503) is in human clinical trials as a vascular disrupting agent.
- Shirali, Anupama,Sriram, Madhavi,Hall, John J.,Nguyen, Benson L.,Guddneppanavar, Rajsekhar,Hadimani, Mallinath B.,Ackley, J. Freeland,Siles, Rogelio,Jelinek, Christopher J.,Arthasery, Phyllis,Brown, Rodney C.,Murrell, Victor Leon,McMordie, Austin,Sharma, Suman,Chaplin, David J.,Pinney, Kevin G.
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experimental part
p. 414 - 421
(2009/12/05)
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- Selective demethylation and debenzylation of aryl ethers by magnesium iodide under solvent-free conditions and its application to the total synthesis of natural products
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An efficient selective demethylation and debenzylation method for aryl methyl/benzyl ethers using magnesium iodide under solvent-free conditions has been developed and applied to the synthesis of natural flavone and biphenyl glycosides. A variety of functional groups including glycoside were tolerated under the reaction conditions. Experimental results indicated that the removal of an O-benzyl group was easier than that of an O-methyl group, regardless of wherever they were meta or para to the carbonyl. Thus selective debenzylation can be achieved for substrates bearing both benzyloxy and methoxy groups.
- Bao, Kai,Fan, Aixue,Dai, Yi,Zhang, Liang,Zhang, Weige,Cheng, Maosheng,Yao, Xinsheng
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experimental part
p. 5084 - 5090
(2010/04/03)
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- Antineoplastic agents. 579. Synthesis and cancer cell growth evaluation of E-stilstatin 3: A resveratrol structural modification
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As an extension of our earlier structure/activity investigation of resveratrol (1a) cancer cell growth inhibitory activity compared to the structurally related stilbene combretastatin series (e.g., 2a), an efficient synthesis of E-stilstatin 3 (3a) and its phosphate prodrug 3b was completed. The trans-stilbene 3a was obtained using a convergent synthesis employing a Wittig reaction with phosphonium bromide 9 as the key reaction step. Deprotection of the Z-silyl ether 13 gave E-stilstatin 3 (3a) as the exclusive product. The structure and stereochemistry of 3a was confirmed by X-ray crystal structure determination.
- Pettit, George R.,Melody, Noeleen,Thornhill, Andrew,Knight, John C.,Groy, Thomas L.,Herald, Cherry L.
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experimental part
p. 1637 - 1642
(2010/03/31)
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- Wet aerobic oxidation of lignin into aromatic aldehydes catalysed by a perovskite-type oxide: LaFe1-xCuxO3 (x=0, 0.1, 0.2)
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The perovskite-type oxide catalyst LaFe1-xCuxO 3 (x=0, 0.1, 0.2) was prepared by the solgel method, and tested as a catalyst in the wet aerobic oxidation (WAO) of lignin into aromatic aldehydes. The lignin conversion and t
- Zhang, Junhua,Deng, Haibo,Lin, Lu
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experimental part
p. 2747 - 2757
(2009/12/26)
-
- Synthesis and antioxidant activities of 3,5-dialkoxy-4-hydroxycinnamamides
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A series of 3,5-dialkoxy-4-hydroxycinnamamides 6 and 7 was synthesized, and their antioxidant activity was assessed using the thiobarbituric acid reactive substance (TBARS) assay. Interestingly, cinnamamides with longer alkoxy groups on the C-3 and C-5 positions display enhanced inhibition, and most of the compounds in the series tested exhibit excellent lipid peroxidation inhibitory activities. Some cinamamides bearing hexyloxy or 2,6-di-tert-butyl-4-methyl phenol groups have submicromolar inhibitory activities.
- Kang, Tae-Souk,Jo, Hyang-Ok,Park, Woo-Kyu,Kim, Jong-Pyung,Konishi, Yasuo,Kong, Jae-Yang,Park, No-Sang,Jung, Young-Sik
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p. 1663 - 1667
(2008/12/21)
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- Design, synthesis, and SAR analysis of cytotoxic sinapyl alcohol derivatives
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Five series totalling 51 of sinapyl alcohol derivatives were designed and synthesized. Their cytotoxicity analyses were performed on six human tumor cell lines such as PC-3, CNE, KB, A549, BEL-7404, and HeLa. Certain sinapyl alcohol derivatives showed significant cytotoxic activities. Compound 14d exhibited especially potent cytotoxicity against the BEL-7404 cell line with an IC 50 value of 0.7 μM, which showed more cytotoxic activity than the positive control, cisplatin. The structure-cytotoxicity relationships were discussed and the CoMFA analysis was performed using the cytotoxic data against HeLa cells as a template.
- Zou, Hong Bin,Dong, Sheng Yi,Zhou, Chang Xin,Hu, Li Hong,Wu, Yi Hang,Li, Hai Bo,Gong, Jing Xu,Sun, Lian Li,Wu, Xiu Mei,Bai, Hua,Fan, Bo Tao,Hao, Xiao Jiang,Stoeckigt, Joachim,Zhao, Yu
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p. 2060 - 2071
(2007/10/03)
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- Photostable cationic organic sunscreen compounds with antioxidant properties and compisitions obtained therefrom
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Compounds of Formula (I) F Each R is independtly linear or branched C1 to C8 alkyl, or linear or branched C1 to C8 alkoxy or one R is H and the other R is linear or branched C1 to C8 alkyl, or linear or branched C1 to C8 alkoxy; R1 is selected from the group consisting of COCH3,CO2R3, CONH2, COHR(R4)2, CN, COX(CH2)n-N-(R2)(R4)(R3), and the quaternized salt form of the formula COX(CH2)-N-n-(R2)(R4)(R3)-Y; X is O or NH; n is an integer of 1 to 5; Y is an anion; and R2, R3 and R4 are independently lilnear or branched C1 to C20. Hair care formulations and other compounds containing compounds of Formula (I), and methods for protecting hair and substrates such as polymers, textiles, fabrics, leathers and paints the compounds herein.
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Page/Page column 13
(2008/06/13)
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- Enantioselective synthesis of several natural virologins
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An enantioselective synthesis of Virologins 1-(S and R), 2-trans-(S and R) and 3-cis-(S and R) were achieved by Mitsunobu reaction to construct a chiral center and Ando reagent to form cis-olefin.
- Su, Ying,Ren, Xin-Feng,She, Xue-Gong,Pan, Xin-Fu
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p. 1333 - 1337
(2007/10/03)
-