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1.
Optical Review - To increase the recording density of optical discs, analog recording techniques such as the use of orthogonal frequency division multiplexing (OFDM) method has been investigated.... 相似文献
2.
Dr. Peter B. Karadakov Dr. Shohei Saito 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(24):9312-9314
The simple anti-aufbau DFT approach for estimating singlet excited state aromaticity suggested in a recent Communication published in this journal is shown to produce incorrect results because it targets a linear combination of the singlet and triplet configurations involving the HOMO and LUMO rather than the first singlet excited state. If the S1 state of a molecule is dominated by the HOMO→LUMO excitation, a comparably simple but theoretically consistent and qualitatively correct approximation to the S1 wavefunction can be achieved by performing a small “two electrons in two orbitals” CASSCF(2,2) calculation which can be followed by the evaluation of magnetic aromaticity criteria such as NICS. 相似文献
3.
Haruka Takeuchi Prof. Dr. Shinsuke Inuki Kohei Nakagawa Takaaki Kawabe Dr. Atsuhiko Ichimura Prof. Dr. Shinya Oishi Prof. Dr. Hiroaki Ohno 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21396-21401
We report herein a nonbiomimetic strategy for the total synthesis of the plicamine-type alkaloids zephycarinatines C and D. The key feature of the synthesis is a stereoselective reductive radical ipso-cyclization using visible-light-mediated photoredox catalysis. This cyclization enabled the construction of a 6,6-spirocyclic core structure through the addition of a carbon-centered radical onto the aromatic ring. Biological evaluation of zephycarinatines and their derivatives revealed that the synthetic derivative with a keto group displays moderate inhibitory activity against LPS-induced NO production. This approach could offer future opportunities to expand the chemical diversity of plicamine-type alkaloids as well as providing useful intermediates for their syntheses. 相似文献
4.
Prof. Isao Fujii Dr. Makoto Hashimoto Kaori Konishi Akiko Unezawa Haruka Sakuraba Kenta Suzuki Harue Tsushima Miho Iwasaki Satsuki Yoshida Akane Kudo Rina Fujita Aika Hichiwa Koharu Saito Dr. Takashi Asano Dr. Jun Ishikawa Dr. Daigo Wakana Dr. Yukihiro Goda Ayumi Watanabe Mamoru Watanabe Yui Masumoto Dr. Junichiro Kanazawa Dr. Hajime Sato Prof. Masanobu Uchiyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8542-8548
Shimalactones A and B are neuritogenic polyketides possessing characteristic oxabicyclo[2.2.1]heptane and bicyclo[4.2.0]octadiene ring systems that are produced by the marine fungus Emericella variecolor GF10. We identified a candidate biosynthetic gene cluster and conducted heterologous expression analysis. Expression of ShmA polyketide synthase in Aspergillus oryzae resulted in the production of preshimalactone. Aspergillus oryzae and Saccharomyces cerevisiae transformants expressing ShmA and ShmB produced shimalactones A and B, thus suggesting that the double bicyclo-ring formation reactions proceed non-enzymatically from preshimalactone epoxide. DFT calculations strongly support the idea that oxabicyclo-ring formation and 8π-6π electrocyclization proceed spontaneously after opening of the preshimalactone epoxide ring through protonation. We confirmed the formation of preshimalactone epoxide in vitro, followed by its non-enzymatic conversion to shimalactones in the dark. 相似文献
5.
Nickel‐Promoted Highly Regioselective Carboxylation of Aryl Ynol Ether and Its Application to the Synthesis of Chiral β‐Aryloxypropionic Acid Derivatives 下载免费PDF全文
Nickel(0)‐promoted carboxylation of aryl ynol ether proceeded in a highly regioselective manner to produce α‐substituted‐β‐aryloxyacrylic acid derivatives. The α‐substituted‐β‐aryloxyacrylic acids were transformed into the corresponding β‐aryloxypropionic acid derivative as an optically active form via rhodium‐catalyzed asymmetric hydrogenation. 相似文献
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Journal of Statistical Physics - We investigate the fundamental relation between entropy production rate and the speed of energy exchange between a system and baths in classical Markov processes.... 相似文献
8.
Nishio Yu Komori Kohei Izawa Seiichiro Fukunishi Yu 《Theoretical and Computational Fluid Dynamics》2020,34(1):105-117
Theoretical and Computational Fluid Dynamics - The present study aims to simulate a collision of two droplets containing immiscible liquids by employing a three- dimensional incompressible smoothed... 相似文献
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10.
Ayumi Suzuki Dr. Yuichiro Mutoh Dr. Noriko Tsuchida Chi-Wai Fung Dr. Shoko Kikkawa Prof. Isao Azumaya Prof. Shinichi Saito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(17):3795-3802
Although the chemistry of transition-metal complexes with carbonyl (CO) and thiocarbonyl (CS) ligands has been well developed, their heavier analogues, namely selenocarbonyl (CSe) and tellurocarbonyl (CTe) complexes remain scarce. The limited availability of such CSe and CTe complexes has so far hampered our understanding of the differences between such chalcogenocarbonyl (CE: E=O, S, Se, Te) ligands. Herein, we report the synthesis and properties of a series of cationic half-sandwich ruthenium CE complexes of the type [CpRu(CE)(H2IMes)(CNCH2Ts)][BArF4] (Cp=η5-C5H5−; H2IMes=1,3-dimesitylimidazolin-2-ylidene; ArF=3,5-(CF3)2C6H3). A combination of X-ray diffraction analyses, NMR spectroscopic analyses, and DFT calculations revealed an increasing π-accepting ability of the CE ligands in the order O<S<Se<Te. A variable-temperature NMR analysis of the thus obtained chiral-at-metal CE complexes indicated high stereochemical stability. 相似文献