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81.
Satoru Tamura Masafumi Kaneko Susumu Tanimura Nobutoshi Murakami 《Tetrahedron letters》2010,51(13):1678-3843
A new polyketide peumusolide A was disclosed as an unprecedented NES non-antagonistic inhibitor for nuclear export of MEK, a promising scaffold for antitumor agents with novel mechanism of action, from Peumus boldus Molina. The absolute stereostructure as well as optical purity was established by use of the two synthesized enantiomeric model lactones. In addition, the Δε values in their CD spectra were demonstrated to be the conclusive index for determination of not only configuration at C-3 but also optical purity of natural congeneric polyketides. Peumusolide A was revealed to show NES non-antagonistic action by the biotinylated probe and to inhibit proliferation of MEK-activated tumor cells selectively. 相似文献
82.
Tsuyoshi Satoh Takayuki Kuramoto Shingo Ogata Hiroyuki Watanabe Takahito Saitou Makoto Tadokoro 《Tetrahedron: Asymmetry》2010,21(1):1-5
Treatment of enantiomerically pure 1-chlorovinyl p-tolyl sulfoxides, derived from cyclic ketones and (R)-chloromethyl p-tolyl sulfoxide, with the lithium enolate of tert-butyl carboxylates gave adducts in quantitative yields as single diastereomers. The adducts were treated with i-PrMgCl in toluene to afford optically active bicyclo[n.1.0]alkanes bearing a tert-butyl carboxylate moiety in up to 99% enantiomeric excess through the enantioselective 1,3-CH insertion reaction of the generated chiral magnesium carbenoids. This is the first example of the enantioselective 1,3-CH insertion reaction of magnesium carbenoid. 相似文献
83.
K. Hirose M. Ejima T. Fujibayashi Y. Fujii K. Futatsukawa O. Hashimoto T. Ishikawa S. Kameoka H. Kanda F. Kato S. Kinoshita T. Kinoshita T. Kon O. Konno K. Maeda A. Matsumura Y. Miura F. Miyahara H. Miyase T. Nakabayashi S.N. Nakamura H. Nomura K. Nonaka A. Ohtani Y. Okayasu M. Oyamada A. Sasaki H. Shimizu T. Takahashi T. Tamae H. Tamura T. Terasawa H. Tsubota K. Tsukada D. Uchida M. Ukai M. Wakamatsu T. Watanabe H. Yamauchi H. Yamazaki K. Yawata 《Physics letters. [Part B]》2009
84.
Y. Leon P. Sciau P. Goudeau N. Tamura S. Webb A. Mehta 《Applied Physics A: Materials Science & Processing》2010,99(2):419-425
In addition to the red terra sigillata production, the largest Gallic workshop (La Graufesenque) made a special type of terra sigillata, called “marbled” by the archaeologists. Produced exclusively at this site, this pottery is characterized by a surface finish
made of a mixture of yellow and red slips. Because the two slips are intimately mixed, it is difficult to obtain the precise
composition of one of the two constituents without contamination from the other. In order to obtain very precise correlation
at the appropriate scale between the color aspect and the elemental and mineralogical phase distributions in the slip, combined
electron microprobe, X-ray micro spectroscopies and micro diffraction on cross-sectional samples were performed. The aim of
this study is to discover how potters were able to produce this unique type of terra sigillata and especially this particular slip of an intense yellow color. Results show that the yellow component of marbled sigillata was made from a titanium-rich clay preparation. The color is due to the formation of a pseudobrookite (TiFe2O5) phase in the yellow part of the slip, the main characteristics of that structure being considered nowadays as essential
for the fabrication of stable yellow ceramic pigments. Its physical properties such as high refractive indices and a melting
point higher than that of most silicates widely used as ceramic colorants are indeed determinant for this kind of application.
Finally, the red parts have a similar composition (elementary and mineralogical) to the one of standard red slip. 相似文献
85.
Kengo Shamoto Atsushi Miyazaki Mika Matsukura Yuki Kobayashi Takayuki Shioiri 《合成通讯》2013,43(10):1425-1431
A nonenzymatic kinetic resolution of (±)-trans-2-arylcyclohexanols was carried out by esterification using polymer-supported N,N′-dicyclohexylcarbodiimide (DCC), dimethylaminopyridine (DMAP), and 3β-acetoxyetienic acid. The efficiency of the kinetic resolution was comparable to the enzymatic method when arylcyclohexanols bearing a condensed-aromatic ring were used. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communication® to view the free supplemental file. 相似文献
86.
For a spatial characteristic, there exist commonly fat-tail frequency distributions of fragment-size and -mass of glass, areas enclosed by city roads, and pore size/volume in random packings. In order to give a new analytical approach for the distributions, we consider a simple model which constructs a fractal-like hierarchical network based on random divisions of rectangles. The stochastic process makes a Markov chain and corresponds to directional random walks with splitting into four particles. We derive a combinatorial analytical form and its continuous approximation for the distribution of rectangle areas, and numerically show a good fitting with the actual distribution in the averaging behavior of the divisions. 相似文献
87.
Isao Kadota Takayuki Kishi Yuka Fujisawa Yuji Yamagami Hiroyoshi Takamura 《Tetrahedron letters》2010,51(30):3960-5853
A convenient method for the stereoselective construction of angular methyl group of fuzed cyclic ethers is described. Reactions of mixed thioacetals with Me2Zn/Zn(OTf)2 afforded the corresponding methylated products in good yields. Various protective groups such as MOM ether, benzylidene acetal, TBS ether, and pivaloyl group were stable under the reaction conditions. 相似文献
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