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941.
942.
Cover Picture: Controlled Synthesis of Nanoporous Nickel Oxide with Two‐Dimensional Shapes through Thermal Decomposition of Metal–Cyanide Hybrid Coordination Polymers (Chem. Eur. J. 9/2015)
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943.
944.
945.
Akinori Mori 《Tetrahedron》2007,63(5):1270-1280
We have found that phenolic hydroxyl groups were readily deoxygenated via aryl sulfonate under the Pd/C-catalyzed hydrogenation conditions in the presence of diethylamine and the method could also be applicable to the hydrodeoxygenation of morphine to afford 3-deoxy-7,8-dihydromorphine. Diethylamine is not only a scavenger of the corresponding methanesulfonic acid derivative, which is produced during the reaction progress, but also a strong promoter of the Pd/C-catalyzed reduction of aryl sulfonates. This catalyst system could provide a general method for the deoxygenation of various phenol derivatives because of its mild reaction conditions, ease of handling, and no need of particular apparatus. 相似文献
946.
Yusuke Asakuma Kyuya Nakagawa Kouji Maeda Keisuke Fukui 《Polymer Degradation and Stability》2009,94(2):240-245
The depolymerization reaction of polyethylene terephthalate (PET) was analyzed using a computational chemistry approach. The reaction is a type of transesterification reaction using alkoxide. In this study we employed the calculated optimum structure, electrostatic potential distribution, activation energy, electric charges and pathway to investigate the mechanism. We found that the tetrahedral intermediate produced by ring formation with alkoxide is an essential feature of the depolymerization process. Moreover, there is a possibility that a PET molecule is depolymerized by multiple alkoxides at the same time. However, the effects of degree of polymerization and the position of attack by the alkoxides do not strongly influence the reactivity. 相似文献
947.
Hiromitsu Kiriyama Michiaki Mori Yoshiki Nakai Takuya Shimomura Manabu Tanoue Atushi Akutsu Hajime Okada Tomohiro Motomura Shuji Kondo Shuhei Kanazawa Akito Sagisaka Jinglong Ma Izuru Daito Hideyuki Kotaki Hiroyuki Daido Sergei Bulanov Toyoaki Kimura Toshiki Tajima 《Optics Communications》2009,282(4):625-2346
We demonstrate a high-contrast, high-intensity double chirped-pulse amplification (CPA) Ti:sapphire laser system using an optical parametric chirped-pulse (OPCPA) pre- amplifier. By injecting cleaned microjoule seed pulses into the OPCPA, a temporal contrast greater than 1010 within picosecond times before the main femtosecond pulse is demonstrated with an output pulse energy of 1.7 J and a pulse duration of 30 fs, corresponding to a peak power of 60 TW at a 10 Hz repetition rate. This system uses a cryogenically-cooled Ti:sapphire final amplifier and generates focused peak intensities in excess of 1020 W/cm2. 相似文献
948.
Total synthesis and structural elucidation of khafrefungin, a novel antifungal agent isolated from the fermentation culture MF6020, have been achieved. Unlike other inhibitors that inhibit the corresponding enzyme in fungi and mammals to the same extent, khafrefungin does not impair sphingolipid synthesis of mammals. The basic strategy for the structural elucidation is to prepare all stereoisomers of the structurally simplified khafrefungin mimics 1 and 2 that were designed for the elucidation of C10,11,12 and C2',3',4' relative stereochemistry, respectively. The comparison of their spectra with those of natural khafrefungin would result in the identification of eight possible stereoisomers, and the analytical details of these eight stereoisomers have led to the complete stereochemical assignment. On the basis of the structural elucidation, the total synthesis of khafrefungin has been accomplished by using tin(II)-catalyzed asymmetric aldol reactions as key steps. 相似文献
949.
We aimed to develop a 6-chloro-N,N-diethyl-1,3,5-triazine-2,4-diamine (CAT)-sensing system based on a biomimetic receptor of a molecularly imprinted polymer for CAT and electrochemical determination of CAT. A molecularly imprinted polymer for CAT was prepared by the polymerization of methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylate (EDMA) as a cross-linker with a template molecule (CAT) in dimethyl formamide (DMF). The polymer prepared with the ratio of these monomers (CAT:MAA:EDMA = 1:7.5:20) showed the most selective rebinding to CAT, and the obtained polymer was recognized as a CAT-imprinted polymer (CAT-MIP). The effect of the specific imprinting sites of CAT-MIP was demonstrated by Scatchard analysis. In an aqueous solution of CAT, CAT-MIP showed the maximum binding of CAT in a 0.05 M phosphate buffer (PB), pH 5.0. The binding amount of CAT to CAT-MIP was 24% more than atrazine and 72% more than propazine. The CAT-sensing system was composed of a column of CAT-MIP particles and a voltammetry analyzer. The reductive current of CAT depended on the concentration of CAT up to 30 microM with the system. 相似文献
950.
Yusuke Nakanishi 《Tetrahedron》2007,63(49):12138-12148
The indene formation from phenyl-substituted sec- and tert-propargyl esters (terminal alkynes) was achieved by platinum or ruthenium catalysis via E-vinylcarbenoid intermediate. Considering the competitive reactions of pentannulation versus cyclopropanation, the equilibrium ratios of E and Z vinylcarbenoid intermediates from sec- and tert-propargyl esters are estimated at ca. 10:90 and 40:60, respectively. Two reaction pathways, Nazarov-type cyclization and/or metallacycle from styrylcarbenoid species, are proposed by considering ratios of products in the control experiment. 相似文献