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Heck reactions between iodobenzene and methyl acrylate were carried out in monoglyme and diglyme as solvents, using different ligands and palladium sources, and good to high yields were obtained in the production of (E)‐substituted olefins. The ionic liquid BmimCl was successfully utilized as pre‐ligand to substitute triphenylphosphine. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Aires da Conceição Silva Lucia C.S. Aguiar Andréa Luzia F. de Souza Luiz Fernando Brum Malta 《Tetrahedron letters》2010,51(30):3883-6491
In this work, we present ligand-free Suzuki cross-coupling reactions in PEG 300 under thermal conditions at 55 °C with good yields of conversion; better results were obtained with low reaction time. In 1 hour, 1-iodo-4-nitrobenzene and phenylboronic acid reached 98% of the yield and 9700 of TON. Better results were obtained with Pd(0) sources. The reaction system was recycled up to three times with good activity. 相似文献
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Suzuki–Miyaura reactions between halobenzenes and other substituted (hetero)arenes and boronic acids were carried out in PEG–water solution using Pd/BaSO4 as catalytic source in a ligand‐free system. High to moderate yields were generally obtained. The catalytic system could be recycled up to six times, showing a slight decrease in activity after each cycle. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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The construction of natural product-like, tricyclic compounds is reported. Starting from a D-(-)-ribose-derived dihydrofurane, the tricyclic scaffold is prepared via an intramolecular hetero-Diels-Alder reaction. The reaction proceeds with very high diastereoselectivity through an endo transition state, as established on the basis of X-ray structural analysis of the products. Further modification and derivatization of the obtained products is described. 相似文献
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Edjane F. B. Silva Marcílio P. Ribeiro Luzia P. F. C. Galvão Valter J. Fernandes Antonio S. Araujo 《Journal of Thermal Analysis and Calorimetry》2011,103(2):465-469
Degradation of low density polyethylene (LDPE) was studied for the pure polymer and mixed with silicoaluminophosphate SAPO-11
catalyst. SAPO-11 was synthesized by hydrothermal method using di-isoprolpylamine as structure template, and characterized
by XRD and SEM. From X-ray diffraction, it was observed that SAPO-11 was obtained with high crystallinity. Using the model-free
kinetics, proposed by Vyazovkin, the activation energies were determined for the process of polymer degradation. It was found
that the degradation process of 90% of LDPE mixed with SAPO-11 over a period of 1 h, occurred at a temperature of 378 °C,
while for the pure LDPE, the temperature was increased to 434 °C in the same period of time and conversion, indicating that
SAPO-11 was an effective catalyst for the degradation of LDPE. The activation energy for the degradation of pure LDPE was
equivalent to 251 kJ mol−1. Also, when the SAPO-11 was mixed with the polymer, this value was decreased to 243 kJ mol−1. 相似文献
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In this paper we continue to develop the topological method to get semigroup generators of semi-simple Lie groups. Consider a subset \(\Gamma \subset G\) that contains a semi-simple subgroup \(G_{1}\) of G. If one can show that \( \Gamma \) does not leave invariant a contractible subset on any flag manifold of G, then \(\Gamma \) generates G if \(\mathrm {Ad}\left( \Gamma \right) \) generates a Zariski dense subgroup of the algebraic group \(\mathrm {Ad}\left( G\right) \). The proof is reduced to check that some specific closed orbits of \(G_{1}\) in the flag manifolds of G are not trivial in the sense of algebraic topology. Here, we consider three different cases of semi-simple Lie groups G and subgroups \(G_{1}\subset G\). 相似文献
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Burin VM Arcari SG Costa LL Bordignon-Luiz MT 《Journal of chromatographic science》2011,49(8):647-651
A methodology employing reversed-phase high-performance liquid chromatography (RP-HPLC) was developed and validated for simultaneous determination of five phenolic compounds in red wine. The chromatographic separation was carried out in a C(18) column with water acidify with acetic acid (pH 2.6) (solvent A) and 20% solvent A and 80% acetonitrile (solvent B) as the mobile phase. The validation parameters included: selectivity, linearity, range, limits of detection and quantitation, precision and accuracy, using an internal standard. All calibration curves were linear (R(2) > 0.999) within the range, and good precision (RSD < 2.6%) and recovery (80-120%) was obtained for all compounds. This method was applied to quantify phenolics in red wine samples from Santa Catarina State, Brazil, and good separation peaks for phenolic compounds in these wines were observed. 相似文献
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Soares BM Alves OA Ferreira MV Amorim JC Sousa GR Silveira Lde B Prates RA Avila TV Baltazar Lde M de Souza Dda G Santos DA Modolo LV Cisalpino PS Pinotti M 《Photochemistry and photobiology》2011,87(2):357-364
Cryptococus gattii is an emergent primary human pathogen that causes meningismus, papilledema, high intracranial pressure and focal involvement of the central nervous system in immunocompetent hosts. Prolonged antifungal therapy is the conventional treatment, but it is highly toxic, selects for resistant strains, contributes to therapy failure and has a poor prognosis. Photodynamic inactivation (PDI) offers a promising possibility for the alternative treatment of cryptococcosis. The aim of this study was to test the effectiveness of toluidine blue O (TBO) and light-emitting diode (LED) against C. gattii strains with distinct susceptibility profile to antifungal drugs (amphotericin B: 0.015-1.0 μg mL(-1); itraconazole: 0.015-2 μg mL(-1); fluconazole: 4-64 μg mL(-1)). Using 25 μM (6.76 μg mL(-1)) TBO and LED energy density of 54 J cm(-2) these fungal isolates presented variable susceptibility to PDI. The production of reactive oxygen species (ROS)/peroxynitrite was determined, and the catalase and peroxidase activities were measured. After PDI, high amounts of ROS/peroxynitrite are produced and higher catalase and peroxidase activities could be correlated with a lower susceptibility of C. gattii isolates to PDI. These results indicate that PDI could be an alternative to C. gattii growth inhibition, even of isolates less susceptible to classical antifungal drugs, also pointing to mechanisms related to their variable susceptibility behavior. 相似文献