- Oxidative transformation of the natural lignan hydroxymatairesinol with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
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The oxidative transformation of the two isomers of the natural lignan hydroxymatairesinol from Norway Spruce (Picea abies) by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), has been studied. Significant differences in the outcome of the reactions were observed when the pure isomers of hydroxymatairesinol were reacted with DDQ under the same conditions. The different stereoelectronic effects in the two isomers as well as their conformational structures seem to determine the site of reaction, which results in different reaction products. Several products were identified by GC-MS and NMR spectroscopy. Oxomatairesinol was obtained in a yield of 25%.
- Eklund, Patrik C.,Sj?holm, Rainer E.
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- Kinetics of the selective oxidation of the lignan hydroxymatairesinol to oxomatairesinol over Au/Al2O3 catalysts
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Lignan hydroxymatairesinol (HMR) extracted from Norway spruce knots was oxidized to the lignan oxomatairesinol (oxoMAT) in a semi-batch glass reactor under the atmospheric pressure in the presence of oxygen (5-49 vol.% in nitrogen) over 2 wt.% Au/Al2O3 catalyst, using propan-2-ol-water mixture as a solvent. The following kinetic parameters were determined: adsorption constants, rate constants, reaction order for reagents, and energy of activation. Through the parameter estimation the experimental data were fitted to the advanced kinetic model demonstrating a good correlation between the model and experiments.
- Simakova, Olga A.,Murzina, Elena V.,W?rn?, Johan,Murzin, Dmitry Yu.
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- Oxygen-assisted hydroxymatairesinol dehydrogenation: A selective secondary-alcohol oxidation over a gold catalyst
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Selective dehydrogenation of the biomass-derived lignan hydroxymatairesinol (HMR) to oxomatairesinol (oxoMAT) was studied over an Au/Al2O 3 catalyst. The reaction was carried out in a semi-batch glass reactor at 343 K under two different gas atmospheres, namely produced through synthetic air or nitrogen. The studied reaction is, in fact, an example of secondary-alcohol oxidation over an Au catalyst. Thus, the investigated reaction mechanism of HMR oxidative dehydrogenation is useful for the fundamental understanding of other secondary-alcohol dehydrogenation over Au surfaces. To investigate the elementary catalytic steps ruling both oxygen-free- and oxygen-assisted dehydrogenation of HMR to oxoMAT, the reactions were mimicked in a vacuum over an Au28 cluster. Adsorption of the involved molecular species - O2, three different HMR diastereomers (namely, one SRR and two RRR forms), and the oxoMAT derivative - were also studied at the DFT level. In particular, the energetic and structural differences between SRR-HMR and RRR-HMR diastereomers on the Au28 cluster were analyzed, following different reaction pathways for the HMR dehydrogenation that occur in presence or absence of oxygen. The corresponding mechanisms explain the higher rates of the experimentally observed oxygen-assisted reaction, mostly depending on the involved HMR diastereomer surface conformations. The role of the support was also elucidated, considering a very simple Au28 charged model that explains the experimentally observed high reactivity of the Au/Al 2O3 catalyst.Copyright
- Prestianni, Antonio,Ferrante, Francesco,Simakova, Olga A.,Duca, Dario,Murzin, Dmitry Yu.
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- Gold particle size effect in biomass-derived lignan hydroxymatairesinol oxidation over Au/Al2O3 catalysts
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The heterogeneously catalyzed aerobic selective oxidation of naturally occurring lignan hydroxymatairesinol (HMR) to another lignan oxomatairesinol (oxoMAT) was carried out at 70°C and atmospheric pressure over gold nanoparticles with different sizes supp
- López, Martín,Simakova, Olga A.,Murzina, Elena V.,Willf?r, Stefan M.,Prosvirin, Igor,Simakov, Andrey,Murzin, Dmitry Yu.
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p. 248 - 255
(2015/02/19)
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- Oxidative dehydrogenation of a biomass derived lignan - Hydroxymatairesinol over heterogeneous gold catalysts
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Synthesis of the lignan oxomatairesinol via oxidative dehydrogenation of the naturally occurring lignan hydroxymatairesinol was studied over gold catalysts supported on C, TiO2, SiO2, Al2O 3, and MgO. In order to investigate the reaction performance over the gold catalyst, synthesis of lignan oxomatairesinol was carried out in different organic solvents/water mixtures under synthetic air and nitrogen atmosphere at 373 K, and using also isolated hydroxymatairesinol isomers as a starting material. The results were compared with those obtained over palladium catalysts. Synthesized supported gold catalysts as well as the corresponding supports were characterized by TEM, XRD, ICP-OES, CO2-TPD, FTIR (using pyridine as a probe molecule), and XPS. Gold catalysts were shown to display superior performance compared with palladium ones: the activity was 4 times higher, with selectivity toward oxomatairesinol being 100%, while 60-85% were obtained over palladium catalysts. In contrast to palladium, the activity of gold catalysts is high in aerobic conditions and water-propan-2-ol mixture. However, activity and selectivity of gold catalysts were shown to be dependent on the electronic state of the metal and, similar to palladium catalysts, on the support acidity.
- Simakova, Olga A.,Murzina, Elena V.,Maeki-Arvela, Paeivi,Leino, Anne-Riikka,Campo, Betiana C.,Kordas, Krisztian,Willfoer, Stefan M.,Salmi, Tapio,Murzin, Dmitry Yu.
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experimental part
p. 54 - 64
(2011/09/20)
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- A novel and efficient synthesis of highly oxidized lignans by a methyltrioxorhenium/hydrogen peroxide catalytic system. Studies on their apoptogenic and antioxidant activity
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Highly oxidized lignans produced during the cytochrome P-450 metabolism in the cells show biological activities significantly different from those of their parent natural compounds. Lignans precursors of mammalian enterolignans were treated with a methylt
- Bernini, Roberta,Gualandi, Giampiero,Crestini, Claudia,Barontini, Maurizio,Belfiore, Maria Cristina,Willfoer, Stefan,Eklund, Patrik,Saladino, Raffaele
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experimental part
p. 5676 - 5682
(2009/12/09)
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- Radical and superoxide scavenging activities of matairesinol and oxidized matairesinol
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The radical and superoxide scavenging activities of oxidized matairesinols were examined. It could be assumed that the free benzylic position was important for higher radical scavenging activity. The different level of activity was observed between 7′-oxomatairesinol (Mat 2) and 7-oxomatairesinol (Mat 3). The activity of 8-hydroxymatairesinol was lower than that of matairesinol (Mat 1). The superoxide scavenging activity of the oxidized matairesinols was also demonstrated for the first time. It is assumed that the pKa value of phenol in the oxidized matairesinols affected this activity.
- Yamauchi, Satoshi,Sugahara, Takuya,Nakashima, Yuki,Okada, Akihiro,Akiyama, Koichi,Kishida, Taro,Maruyama, Masashi,Masuda, Toshiya
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p. 1934 - 1940
(2008/02/08)
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- Radical carboxyarylation approach to lignans. Total synthesis of (-)-arctigenin, (-)-matairesinol, and related natural products
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Total syntheses of seven biologically important lignan natural products, including (-)-arctigenin, (-)-matairesinol, and (-)α-conidendrin, by way of a highly stereoselective domino radical sequence is presented. The reported stereochemistry of the natural product 7-hydroxyarctigenin is shown to be erroneous; a diastereoisomeric structure is assigned to the natural product.
- Fischer, Joshua,Reynolds, Aaron J.,Sharp, Lisa A.,Sherburn, Michael S.
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p. 1345 - 1348
(2007/10/03)
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