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971.
972.
973.
Masaki Takahashi Yusuke Murata Yuki Hakamata Kohei Suzuki Tetsuya Sengoku Hidemi Yoda 《Tetrahedron》2012,68(38):7997-8002
The first stereocontrolled synthesis of vittarilide-A and its C5-epimer was completed from d-glucuronolactone. Comparison with the spectroscopic properties reported for authentic material has given a clear indication as to the absolute stereochemistry of the natural vittarilide-A. 相似文献
974.
Stereoselective Synthesis and Physicochemical Properties of Liquid‐Crystal Compounds Possessing a trans‐2,5‐Disubstituted Tetrahydropyran Ring with Negative Dielectric Anisotropy
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Dr. Keisuke Araki Dr. Tetsuya Yamamoto Dr. Ryoji Tanaka Makoto Ushioda Dr. Yasuyuki Gotoh Dr. Tetsu Yamakawa Dr. Munenori Inoue 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2458-2466
Three stereoselective syntheses and the physicochemical properties of trans,trans‐5‐(4‐ethoxy‐2,3‐difluorophenyl)‐2‐(4‐propylcyclohexyl)tetrahydropyran, which is an important liquid‐crystal compound with a large negative dielectric anisotropy (Δε=?7.3), are described. The key step in the construction of the trans‐2,5‐disubstituted tetrahydropyran ring in the first approach involved a benzylic cation mediated intramolecular olefin cyclization of a 2‐allyloxy‐1‐arylethanol derivative. The second method included the Et2Zn‐induced 1,2‐aryl shift of a bromohydrin obtained from a hetero‐Diels–Alder reaction, followed by stereoselective bromination. The third approach utilized the hetero‐Diels–Alder reaction of trans‐4‐propylcyclohexanecarboxaldehyde and a 2‐aryl‐3‐(trimethylsilyl)oxy‐1,3‐butadiene, followed by stereoselective protonation. From results obtained by using a quantum chemical calculation method, the reason why the target compound shows a large negative Δε value is discussed. 相似文献
975.
Takashi Sugane Noritaka Hamada Takahiko Tobe Wataru Hamaguchi Itsuro Shimada Kyoichi Maeno Junji Miyata Takeshi Suzuki Tetsuya Kimizuka Shuichi Sakamoto Shin-ichi Tsukamoto 《Tetrahedron: Asymmetry》2012,23(22-23):1528-1533
Herein we describe a novel and efficient method for synthesizing the (R)-atropisomer of 3-[3-ethyl-5-(6-phenylpyridin-3-yl)-4H-1,2,4-triazol-4-yl]-2-methylbenzonitrile 1, a novel GlyT1 inhibitor. The diastereomeric salt formation of 3-[3-ethyl-5-(6-phenylpyridin-3-yl)-4H-1,2,4-triazol-4-yl]-2-methylbenzoic acid 7 with (1R,2S)-(?)-2-amino-1,2-diphenylethanol afforded the desired (R)-atropisomer. We also report the determination of the absolute configuration of (R)-7 by powder X-ray diffraction. 相似文献
976.
977.
978.
Inside Cover: Photothermal Conversion of CO2 into CH4 with H2 over Group VIII Nanocatalysts: An Alternative Approach for Solar Fuel Production (Angew. Chem. Int. Ed. 43/2014)
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979.
Hiroki Miura Kazuki Takeuchi Tetsuya Shishido 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(1):286-290
Intermolecular [2+2+1] carbonylative cycloaddition of aldehydes with alkynes and subsequent oxidation to γ‐hydroxybutenolides is achieved using a supported ruthenium catalyst. A ceria‐supported ruthenium catalyst promotes the reaction efficiently, even with an ambient pressure of CO or without external CO, thus giving the corresponding γ‐hydroxybutenolide derivatives in good to high yields. Moreover this catalyst can be reused with no loss of activity. 相似文献
980.
In the organoborane chemistry, the homologation reaction is one of the useful methods for the synthesis of organoboranes not available via hydroboration.1) The allylic boranes are known to be highly reactive and exhibit specific behaviors,2) but with few exceptions,3) these are difficult to be prepared directly by the hydroboration reaction.5) Previously, we reported that in the reaction of the dianion of phenoxyacetic acid with organoborane, the phenoxy group acts as a good leaving group.6) This result suggested us a new homologation reaction converting a saturated organoborane to a allylic borane (1) by the treatment with the carbanion of allyl phenyl ether. Here we wish to report the synthesis of 1-alkenes (II) three-carbon-homologated from starting alkenes7) and the regioselective synthesis of 1,5-dienes (III) using allylic borane intermediates (1) (eq. 1). 相似文献