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31.
Ryu I Miyazato H Kuriyama H Matsu K Tojino M Fukuyama T Minakata S Komatsu M 《Journal of the American Chemical Society》2003,125(19):5632-5633
Free-radical mediated stannylcarbonylation of azaenynes provides a general [n + 1]-type annulation approach leading to alpha-stannylmethylene lactams. The cyclization is unusual in its breadth, covering 4-exo, 5-exo, 6-exo, 7-exo, and 8-exo modes. 相似文献
32.
Keitaro Ishii Takuya Sone Yukio Shimada Takahide Shigeyama Masahiro Noji Shigeo Sugiyama 《Tetrahedron》2004,60(48):10887-10898
The photochemical C,C-bond cleavage of N-benzyl β-aziridinylacrylonitrile 1 and acrylate 2 and the subsequent [3+2] cycloaddition with electron-deficient alkenes afforded head-to-head adducts selectively and efficiently. Irradiation of N-phenyl aziridine 3 with acrylonitrile gave adducts, but photoreaction of N-benzoyl aziridine 4 and thermal reactions of 3 and 4 with alkenes yielded C(γ),N-cleaved products instead of cycloadducts. N-trityl aziridine 5 also reacted with electron-deficient alkenes, affording 2,3-cis-pyrrolidine derivatives exclusively. A formal synthesis of a pyrrolizidine alkaloid, isoretronecanol (27), starting from 5 was achieved in a convenient manner. 相似文献
33.
[reaction: see text] Ketone alpha,delta-dianions are generated by vinylogous extension of ketone alpha,beta-dianions with alkenes such as vinylarenes, vinylsilanes, and vinyl sulfides, which then undergo reactions at the delta and alpha positions with different electrophiles, creating ketone frameworks. This work represents a cascade-type anion method that achieved three- and four-carbon component assembly reactions leading to ketones. 相似文献
34.
Using a scattering technique based on a parametrized linear combination of atomic orbitals Hamiltonian, we calculate the ballistic quantum conductance of multiwall carbon nanotubes. We find that interwall interactions not only block some of the quantum conductance channels, but also redistribute the current nonuniformly over individual tubes across the structure. Our results provide a natural explanation for the unexpected integer and noninteger conductance values reported for multiwall nanotubes by Stefan Frank et al. [Stefan Frank et al., Science 280, 1744 (1998)]. 相似文献
35.
Seiji Shinkai Kazuyoshi Shigematsu Toshiyuki Ogawa Takahide Minami Osamu Manabe 《Tetrahedron letters》1980,21(46):4463-4466
A new photoresponsive crown ether (I) with an azobenzene-4-oxyacetate function was synthesized. The photo-isomerized cis-(1) extracted K+ ion more selectively than trans-(I) and the thermal cis-trans isomerization was suppressed by added metal ions. 相似文献
36.
To give a redox-switch function to crown ethers, 4′-mercaptomono-benzo-15-crown-5 (CrSH) and its oxidized disulfide form (CrSSCr) were synthesized. The solvent extraction proved that the ion affinity of CrSH is generally greater than that of CrSSCr. 相似文献
37.
[reaction: see text] The PdCl2(PPh3)2-catalyzed Sonogashira coupling reaction, in good to high yields, was performed in an ionic liquid ([BMIm][PF6]) in the absence of a copper salt. The use of an ionic liquid allows for the facile separation and recycling of the catalyst. The application of the above reaction in a microflow system in conjunction with an IMM micromixer was also successful. 相似文献
38.
Takayoshi Kasakado Mamoru Hyodo Akihiro Furuta Aina Kamardine Ilhyong Ryu Takahide Fukuyama 《中国化学会会志》2020,67(12):2253-2257
In this communication flow Friedel–Crafts alkylation was studied using hydroxy-substituted sulfonic acid-functionalized silica as a catalyst and 1-adamantanol as a model substrate. The reaction of 1-adamantanol ( 1a ) with toluene ( 2a ) proceeded well with 5 min of residence time at 120°C to give good yield of 1-tolyladamantane ( 3a ) as a 1:9 mixture of meta and para isomers. When the flow synthesis was carried out over 2.5 hr of running time, the collected five fractions contain the product 3a in 97–92% yields, suggesting the durability of the catalyst. 相似文献
39.
Tatsuki Yasumitsu Gang Liu Jean-Marc Leveque Shuji Aonuma Laurent Duclaux Takahide Kimura Naoki Komatsu 《Ultrasonics sonochemistry》2013,20(1):37-39
Probe-type ultrasonication has been employed for surfactant-aided solubilization, or individualization, of single-walled carbon nanotubes (SWNTs). The resulting solution can be used not only for spectroscopic analyses such as absorption, photoluminescence, and circular dichroism, but also for separation by density gradient ultracentrifugation, dielectrophoresis, chromatography, and polymer wrapping. In spite of its importance, the sonochemical processing of SWNTs has not been considered seriously. Herein, we report on a more efficient cooling cell for probe-type ultrasonication. As compared with a conventional cylindrical cell, the concentration of the SWNTs solubilized in water was found to be almost double in a rosette cooling cell after ultracentrifugation. The efficiency of a rosette cell can be attributed to the higher efficiency in circulation and cooling of the SWNT dispersion as well as enhancement of the cavitation process. 相似文献
40.
Dr. Gang Liu Dr. A. F. M. Mustafizur Rahman Songpol Chaunchaiyakul Prof. Takahide Kimura Prof. Yuji Kuwahara Prof. Naoki Komatsu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16221-16230
We developed a host–guest methodology for separation of single‐walled carbon nanotubes (SWNTs) according to the handedness, diameter and metallicity by the use of diporphyrin nanotweezers and nanocalipers. Although the pyrene has been frequently used to replace porphyrin, due to a similar affinity to the surface of SWNTs and better availability, the extraction and recognition abilities of dipyrene nanotweezers were not so good as those of diporphyrin ones as we reported previously. However, introduction of a tert‐butyl substituent at the 7′‐position of 2‐pyrene is found to enhance the extraction and recognition abilities of dipyrene nanotweezers and nanocalipers. That is, (6,5)‐SWNTs were obtained in high purity by use of bis(tert‐butylpyrene) nanotweezers with a phenanthrene spacer and metallic SWNTs were highly enriched by use of bis(tert‐butylpyrene) nanocalipers with a carbazole–anthracene–carbazole spacer. 相似文献