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81.
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
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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
86.
A single picosecond ultraviolet pulse has been generated based on mode-locking of a dye laser pumped by a long pulse XeCl laser to serve as the input source for a high-power ps KrF laser system. A short-pulse uv dye laser (BBQ) pumped by an additional XeCl laser was used to selectively amplify a single pulse from a mode-locked pulse train with the pulse separation of 3.2 ns. The amplified single pulse was frequency-doubled to 248 nm with the pulse duration of 20 ps. 相似文献
87.
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
88.
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
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