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491.
Tricyclic core skeleton of manzamine A was constructed stereoselectively from the fused nitrogen-containing bicyclic enone 3 via a novel and efficient strategy including sequential stereoselective Diels-Alder reaction, Curtius rearrangement, and intramolecular lactam formation reaction. 相似文献
492.
Pieters S Tistaert C Alaerts G Bodzioch K Mangelings D Dejaegher B Rivière C Hoai NN Van MC Quetin-Leclerq J Vander Heyden Y 《Talanta》2011,83(4):1188-1197
Because of its eminent high resolution potential and minimal solvent consumption, pressurized capillary electrochromatography (pCEC) may offer an interesting alternative to HPLC for screening applications that need to resolve complex samples. In this paper, its potential was assessed in a screening of plant extracts from Mallotus species to indicate compounds with possible antioxidant activities by means of a PLS model built from their pCEC fingerprints. The main aim of this research was to find out whether pCEC can have an added value for this application. To get a complete overview of the techniques potential for this application, it was also assessed whether the technique can meet the requirements in terms of precision, sensitivity and column robustness. Encountered benefits and downsides were reported. Fingerprints with satisfactory sensitivity and precision could be obtained by concentrating the sample 5-fold and using optimized rinsing procedures, respectively. From the generated pCEC fingerprints of 39 Mallotus samples and their respective DPPH radical scavenging activity test results, a three-component PLS model was being built. The model proved good predictive abilities and easily allowed the indication of possible antioxidant compounds in the fingerprints. Despite its much higher peak capacity, the performance of pCEC to fingerprint the majority of the Mallotus extracts did not surpass that of a custom HPLC method. This was also reflected in its comparable power to indicate possible antioxidant compounds in the fingerprints after modeling. Because of its low detection sensitivity and modest column robustness, the benefit of the lower solvent consumption was partly paid-off by the current need for more system maintenance, also limiting the sample throughput. For the considered screening application, pCEC may suit as a viable but no preferred alternative technique. 相似文献
493.
Le TT Chau NT Nguyen TT Brien J Thai TT Nourry A Castanet AS Nguyen KP Mortier J 《The Journal of organic chemistry》2011,76(2):601-608
The metalation of 4-hydroxy-6,7-dimethoxy-8-methyl-2-naphthoic acid (8) affording trianion 6 is presented and applied to the regioselective efficient construction of a series of 5,5'-didesisopropyl-5,5'-dialkylapogossypol derivatives 3 that are potent pan-active inhibitors of antiapoptotic Bcl-2 family proteins. 相似文献
494.
We investigated numerically the scattering cross sections and near-field intensities of solid-silver and silver-shell (shell
thickness d = 10 nm) nanodimers that interact with incident plane wave by the use of finite-element method with three-dimensional models.
Results show that the silver-shell cases exhibit tunable surface plasmon resonances and its rotational effects can induce
more surface plasmons in a wider range of wavelength that are not observed for the solid-silver cases with the same volume
(1,046,666 nm3). 相似文献
495.
Marijke WA de Backer Maike AD Brans Mieneke CM Luijendijk Keith M Garner Dianne MA van den Heuvel R Jeroen Pasterkamp Roger AH Adan 《BMC neuroscience》2010,11(1):94