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101.
L-Daunosamine, the carbohydrate component of a group of important anticancer anthracycline antibiotics, has been efficiently prepared from L-lactic acid in a completely stereoselective manner through direct C-acylation using diphenyl phosphorazidate (DPPA). 相似文献
102.
Akiyoshi Osaka Kanji Tsuru H. Iida Chikara Ohtsuki Satoshi Hayakawa Yoshinari Miura 《Journal of Sol-Gel Science and Technology》1997,8(1-3):655-661
Apatite derived by sol-gel routes through an amorphous state or derived biomimetically is likely to provide chemically and
biologically active surfaces. Thus apatite or apatite-composite particles were prepared by spray-pyrolysis of several solutions
as they were applicable to medical treatment. Calcium lactate and ammonium dihydrogen phosphate aqueous solutions stabilized
with ethylenediaminetetraacetic acid were sprayed ultrasonically and pyrolysed at 600°C to yield amorphous particles of apatite
while apatite-ferric oxide composite powders were prepared from the solutions of calcium lactate and ferric nitrate. Solutions
of calcium nitrate and titanium ethoxide in 0.5 N HNO3 were also spray-pyrolysed at 600°C to prepare calcium titanate and titanium oxide particles trapped on a Ti substrate. Apatite
could biomimetically be developed on the calcium titanate particles when they were soaked in an acellular simulated body fluid. 相似文献
103.
Direct Enantioselective Vinylogous Mannich Reaction of Ketimines with γ‐Butenolide by Using Cinchona Alkaloid Amide/Zinc(II) Catalysts
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Prof. Dr. Shuichi Nakamura Ryota Yamaji Dr. Masashi Hayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(27):9615-9618
A direct enantioselective vinylogous Mannich reaction of ketimines with γ‐butenolide has been developed. Good yields and enantioselectivities were observed for the reaction of various ketimines by using a cinchona alkaloid amide/Zn(OTf)2 catalyst and Et3N. Both enantiomers of the products could be obtained by using pseudoenantiomeric chiral catalysts. 相似文献
104.
The asymmetric total synthesis of UCS1025A is accomplished by establishing a novel and efficient method for the construction of a tricyclic pyrrolizidinone skeleton based on a sequential Michael-retro Michael strategy. The key step is a one-pot six-step cascade reaction including oxidation of a primary alcohol to the corresponding carboxylic acid, a retro thio-Michael reaction, and an intramolecular oxy-Michael reaction. This newly-developed synthetic strategy inspired by “masked” electrophilic character of tricyclic pyrrolizidinone is efficient and high-yielding compared to that developed in previously-reported total syntheses. 相似文献
105.
106.
Recently, observation and tracking of single fluorophores, which we term single fluorophore dynamic imaging (SFDI) in this review, in living cells have been achieved. In particular, the recent success of SFDI of individual proteins tagged with green fluorescent protein (GFP) in live cells has opened new important possibilities for studying events occurring in living cells at the level of single molecules. Specifically, SFDI of GFP allows the tracking of movement and oligomerization levels of individual oligomers (monomers) in living cells and, thus, provides powerful means to investigate the movement, assembly, localization, and activation that signaling molecules undergo following an external stimulus. In this short account, we first review technologically important points for SFDI of GFP molecules in living cells, then give examples of its application, and, finally, propose a synergistic use of SFDI and single-particle tracking, a technique used for investigating single or small groups of molecules in live cells over the past 15 years. 相似文献
107.
Hitoshi Okuda Ryota Seto Yasuhito Koyama Toshikazu Takata 《Journal of polymer science. Part A, Polymer chemistry》2010,48(19):4192-4199
Poly(arylene thioether)s ( PTEs ) containing 9,9′‐spirobifluorene moieties were synthesized in high yields from 9,9′‐spirobifluorene‐2,2′‐bis(N,N‐dimethylcarbamothioate) 4 as the masked dithiol and various difluoroarenes as electrophilic monomers. All PTEs showed high thermal stability: The 10% weight loss temperature as evaluated by thermogravimetric analysis was over 470 °C under both nitrogen and air atmospheres. The glass transition temperature estimated by DSC was in the range 210–270 °C. The PTEs showed high solubility in ordinary organic solvents, such as CHCl3, NMP, and THF. Most PTEs exhibited remarkably high refractive indices ranging from 1.69 to 1.73 at 587.6 nm, whereas no or little birefringence was observed for the PTEs . © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4192–4199, 2010 相似文献
108.
109.
Anthracene derivatives possessing pentafluorobenzoyloxy moieties at 9- and 10-positions showed polymorphism affording two types of fluorescent crystals with blue and bluish green fluorescence in their crystalline state, respectively. Their single crystal X-ray structures showed that the degree of overlap of anthracene moieties was responsible for the difference in fluorescence. Fluorescence in the crystalline state originated in the dimer emission deduced from their excitation spectra. 相似文献
110.