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501.
Total synthesis of the proposed structure of brevenal, a natural marine polycyclic ether product, has been accomplished. The synthesis features (i) convergent synthesis of the pentacyclic polyether skeleton using our developed Suzuki-Miyaura coupling strategy and (ii) construction of the multi-substituted dienal side chain by CuTC-mediated Stille reaction. Comparison of the NMR data of the synthetic compound with those reported for the natural product revealed that the proposed structure of brevenal needs to be revised. 相似文献
502.
An enantioselective total synthesis of aspergillides A and B has been accomplished on the basis of a unified synthetic strategy that exploits stereodivergent intramolecular oxa-conjugate cyclization and Yamaguchi macrolactonization. 相似文献
503.
Md. Chanmiya Sheikh Shunsuke Takagi Asako Ogasawara Masayuki Ohira Ryuta Miyatake Hitoshi Abe Toshiaki Yoshimura Hiroyuki Morita 《Tetrahedron》2010,66(12):2132-3975
The reaction of N-(3-phenylpropionyloxy)phthalimide (1a) and N-tosyloxy (5a,b) derivatives with nucleophiles was examined and found to give the products via Lossen-type rearrangement. In order to obtain the scope of this reaction mechanism, further studies the reaction of several N-sulfonyloxyimide derivatives with various nucleophiles under similar conditions were carried out and found to afford the corresponding same types of products in high yields. 相似文献
504.
We propose a dechlorination process that allows safe and environmental conversion of chlorinated fluorocarbons. Starting with dissolving a fluorocarbon in an alcohol–NaOH solution, the fluorocarbons are reacted with alcohol–NaOH solvents at room temperature and pressure. In this work, the effect of the NaOH concentration on the solubility of CCl2F2 (CFC-12), CH2F2 (HFC-32), C2HF5 (HFC-125), C2H2F4 (HFC-134a) and C2H4F2 (HFC-152a) in methanol–NaOH, ethanol–NaOH and 1-propanol–NaOH solutions was measured. The experimental salting-out effects can be explained by solvation of a few alcohol molecules on sodium ion. Setchenov coefficients were determined and found to be independent of temperature. 相似文献
505.
R. da Costa Lima Magali Silveira Pinho T. Ogasawara 《Journal of Thermal Analysis and Calorimetry》2009,97(1):131-136
The focus of this work is the use of thermal analyses and Fourier Transform Infrared Spectroscopy (FTIR) for characterization
of the gel decomposition, resulting from the formation of Y-barium hexaferrite substituted by Zn ions (Zn-Y-barium hexaferrite).
Samples with Ba2Zn2Fe12O22 composition were synthesized by the citrate auto-combustion method. During the TG experiments the highest mass loss was attributed
to citrate decomposition owing to the self-combustion reaction, confirmed by the disappearance of –OH band, and the drastic
decrease of –CO2
−and –NO3
− bands. Zn substitution resulted in an X-band microwave absorber material. 相似文献
506.
Allixin, a phytoalexin isolated from garlic, was induced by irradiating fresh garlic cloves with sunlight or UV light. Induced allixin was analyzed by HPLC, and the accumulated amounts of allixin were 3.1-6.3 microg/g under experimental conditions. 相似文献
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