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81.
82.
Kaori Kobayashi Takanori Matsui Shozo Tsunekawa 《Journal of Molecular Spectroscopy》2011,269(2):242-247
The trans-ethyl methyl ether molecule has three low-lying torsional modes, that is, two inequivalent methyl internal rotations and an asymmetric skeletal torsion. The internal rotations of the CCH3 and OCH3 methyl rotors and the skeletal torsion correspond to the vibrational modes, ν28, ν29 and ν30 respectively. In this study, the microwave absorption spectrum in the ν28 = 1 CCH3 torsional state was analyzed for the first time. Nine hundred fifty seven lines up to J = 48 and K = 4 were assigned, and the rotational, centrifugal distortion and internal rotational tunneling parameters were determined with the use of a tunneling matrix formalism. By combining the present results on the ν28 = 1 torsional state with those for the ν30 = 1 skeletal torsional state and the ν29 = 1 OCH3 torsional state, torsional couplings are estimated in order to understand quantitatively the inverted A/E sequence patterns observed for those three excited torsional states. 相似文献
83.
Yasuko Ishizuka Hiroshi Nakanishi Takanori Shiraishi Yasuo Kogure Shoichi Kobayashi 《Journal of carbohydrate chemistry》2013,32(4):583-592
ABSTRACT 1H NMR spectra of some oligosaccharide substituted cyclodextrins composed of only α-D-glucose units are analysed. Chemical shifts of protons of each glucosyl group of the chain were determined by experiments with the HOHAHA pulse technique. In spite of the similar kinds of protons, dispersion of chemical shifts is observed. The most dispersed proton is the anomeric proton, and the largest change in the chemical shifts is 0.5 ppm. 相似文献
84.
Taichi Nakano Takashi Miyamoto Takanori Endoh Makoto Shimotani Naoki Ashida Toshishige Morioka Yutaka Takahashi 《应用有机金属化学》2004,18(2):65-67
The palladium‐catalyzed silastannation of acetylenes with tributyl(trimethylsilyl)stannane in the presence of triethylphosphite is reported for the first time. The reaction occurs at room temperature to give (Z)‐silyl(stannyl)ethenes in high yields. The protodemetallation of the resulting adducts with HCl–tetraethylammonium chloride is described first, which demonstrates that the reaction is governed only by the stability of a carbonium ion arising from the protonation to (Z)‐silyl(stannyl)ethenes rather than the hard and soft acid and base principle, i.e. the β‐cation stabilization effect (σ–π stabilization one) of a stannyl group in the carbonium ion is rather significant. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
85.
Katsunori Watabe Hisashi Kanda Katsuya Sato Toshiyuki Hobo 《Journal of chromatography. A》1992,590(2):289-296
In continuous counter-current gas-liquid chromatography, which has a high resolving power and is suitable for the large-scale purification of organic solvents, it is very important that the samples that can be applied extend from easily separable to more difficult to separate, such as azeotropes, low-volatility compounds and stereoisomers. A system was designed and constructed for high-temperature operation up to 200°C, and was applied to the separation of dimethyl and diethyl phthalate, trans- and cis-decahydronaphthalene and cis-decahydronaphthalene and tetrahydronaphthalene. It was confirmed that over 99% of purity could be achieved for dimethyl and diethyl phthalate, trans-decahydronaphthalene, and tetrahydronaphthalene. 相似文献
86.
Total Synthesis of cis‐Clavicipitic Acid from Asparagine via Ir‐Catalyzed CH bond Activation as a Key Step 下载免费PDF全文
Yu‐ki Tahara Mamoru Ito Dr. Kyalo Stephen Kanyiva Prof. Dr. Takanori Shibata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(32):11340-11343
4‐Substituted tryptophan derivatives and the total synthesis of cis‐clavicipitic acid were achieved in reactions in which Ir‐catalyzed C?H bond activation was a key step. The starting material for these reactions is asparagine, which is a cheap natural amino acid. The reductive amination step from the 4‐substituted tryptophan derivative gave cis‐clavicipitic acid with perfect diastereoselectivity. 相似文献
87.
Akiyuki Hamasaki Akiko Muto Shingo Haraguchi Xiaohao Liu Takanori Sakakibara Takushi Yokoyama Makoto Tokunaga 《Tetrahedron letters》2011,52(51):6869-6872
A treatment of cobalt oxide supported gold nanoparticles (Au/Co3O4) under syngas atmosphere effectively generated a cobalt carbonyl-like active species in the reaction vessel. The preparation of Au/Co3O4 was quite simple and the in situ generated cobalt species could be used as a stable and easy handling alternative for dicobalt octacarbonyl without bothersome purification prior to use. The reactions, which are sensitive to the purity of the dicobalt octacarbonyl, such as the alkoxycarbonylation of epoxides and the Pauson-Khand reaction, smoothly progressed with Au/Co3O4. 相似文献
88.
Atsushi TakemuraYasushi Katagiri Kenshu Fujiwara Hidetoshi Kawai Takanori Suzuki 《Tetrahedron letters》2011,52(11):1222-1224
The synthesis of the C22-C37 segment of prorocentin, isolated from the dinoflagellate Prorocentrum lima, was achieved. Because the relative stereochemical relationship between C26 and other stereocenters (C28/C31/C32 established as R*/R*/R*) in the C22-C37 region of natural prorocentin has not yet been determined, both epimers at C26 of the C22-C37 segment were selectively constructed. The synthesis was based on a 5-exo epoxide ring opening reaction to form an oxolane (E-ring), Brown asymmetric methallylation to install the C26-stereocenter, acryloylation of the resulting alcohol, and ring-closing olefin metathesis to establish the Z-olefin at C23/C24. 相似文献
89.
90.
Genki Odahara Shigeki Otani Chuhei Oshima Masahiko Suzuki Tsuneo Yasue Takanori Koshikawa 《Surface and interface analysis : SIA》2011,43(12):1491-1493
We observed in situ growth of a single graphene sheet on Ni(111) by low‐energy electron microscopy. The sheet was grown epitaxially beyond the steps on the substrate. The crystalline shapes of graphene islands were clearly seen; the straight edges of the island are crossed at either 60 or 120°, and the linear edges shifted perpendicular to the edge keeping the equilibrium shape. Graphene islands were united to form a single sheet without any grain boundaries and any wrinkles. The Ni substrate of several centimeters in size was covered with a single‐domain graphene sheet. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献