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991.
992.
Takuya Kumamoto Mika Kainuma Azusa Takahashi Yoshika Matsuo Kazuaki Katakawa Takaaki Taguchi Koji Ichinose 《Molecules (Basel, Switzerland)》2021,26(21)
In this article, we report the total synthesis of 6-deoxydihydrokalafungin (DDHK), a key biosynthetic intermediate of a dimeric benzoisochromanequinone antibiotic, actinorhodin (ACT), and its epimer, epi-DDHK. Tricyclic hemiacetal with 3-siloxyethyl group was subjected to Et3SiH reduction to establish the 1,3-cis stereochemistry in the benzoisochromane, and a subsequent oxidation/deprotection sequence then afforded epi-DDHK. A bicyclic acetal was subjected to AlH3 reduction to deliver the desired 1,3-trans isomer in an approximately 3:1 ratio, which was subjected to a similar sequence to that used for the 1,3-cis isomer that successfully afforded DDHK. A semisynthetic approach from (S)-DNPA, an isolable biosynthetic precursor of ACT, was also examined to afford DDHK and its epimer, which are identical to the synthetic products. 相似文献
993.
Prof. Minoru Mitsumi Yuuki Komatsu Masahiro Hashimoto Prof. Koshiro Toriumi Prof. Yasutaka Kitagawa Prof. Yuji Miyazaki Prof. Hiroki Akutsu Prof. Haruo Akashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3074-3084
The exploration of dynamic molecular crystals is a fascinating theme for materials scientists owing to their fundamental science and potential application to molecular devices. Herein, a one-dimensional (1D) rhodium-dioxolene complex is reported that exhibits drastic changes in properties with the phase transition. X-ray photoelectron spectroscopy (XPS) revealed that the room-temperature (RT) phase is in a mixed-valence state, and therefore, the drastic changes originate from the mixed-valence state appearing in the RT phase. Another notable feature is that the mean square displacements of the rhodium atoms along the 1D chain dramatically increased in the RT phase, indicating a large-amplitude vibration of the Rh−Rh bonds. From these results, a possible mechanism for the appearance of the mixed-valence state in the RT phase was proposed based on the thermal electron transfer from the 1D d-band to the semiquinonato π* orbital coupled with the large-amplitude vibration of the Rh−Rh bonds. 相似文献
994.
Bo Huang Hirokazu Kobayashi Tomokazu Yamamoto Takaaki Toriyama Syo Matsumura Yoshihide Nishida Katsutoshi Sato Katsutoshi Nagaoka Masaaki Haneda Wei Xie Yusuke Nanba Michihisa Koyama Fenglong Wang Shogo Kawaguchi Yoshiki Kubota Hiroshi Kitagawa 《Angewandte Chemie (International ed. in English)》2019,58(8)
995.
Iori Morita Takahiro Mori Takaaki Mitsuhashi Shotaro Hoshino Yoshimasa Taniguchi Takashi Kikuchi Kei Nagae Norihiro Nasu Makoto Fujita Tomohiko Ohwada Ikuro Abe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):4017-4022
C–S bond formation reactions are widely distributed in the biosynthesis of biologically active molecules, and thus have received much attention over the past decades. Herein, we report intramolecular C–S bond formation by a P450 monooxygenase, TleB, which normally catalyzes a C−N bond formation in teleocidin biosynthesis. Based on the proposed reaction mechanism of TleB, a thiol-substituted substrate analogue was synthesized and tested in the enzyme reaction, which afforded the unprecedented sulfur-containing thio-indolactam V, in addition to an unusual indole-fused 6/5/8-tricyclic product whose structure was determined by the crystalline sponge method. Interestingly, conformational analysis revealed that the SOFA conformation is stable in thio-indolactam V, in sharp contrast to the major TWIST form in indolactam V, resulting in differences in their biological activities. 相似文献
996.
Journal of Solid State Electrochemistry - In the present study, an all-solid-state half-cell Li/ amorphous Si (a-Si) was fabricated using the guest Li+ ion conductor (15NaI∙LiBH4) as a solid... 相似文献
997.
Dr. Ryuta Ishikawa Shuya Ueno Shoei Nifuku Dr. Yoji Horii Dr. Hiroaki Iguchi Prof. Yuji Miyazaki Prof. Motohiro Nakano Prof. Shinya Hayami Dr. Shohei Kumagai Dr. Keiichi Katoh Prof. Zhao-Yang Li Prof. Masahiro Yamashita Prof. Satoshi Kawata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(6):1278-1285
The reaction of Fe(OAc)2 and Hbpypz with neutral TCNQ results in the formation of [Fe2(bpypz)2(TCNQ)2](TCNQ)2 ( 1 ), in which Hbpypz=3,5-bis(2-pyridyl)pyrazole and TCNQ=7,7′,8,8′-tetracyano-p-quinodimethane. Crystal packing of 1 with uncoordinated TCNQ and π–π stacking of bpypz− ligands produces an extended two-dimensional supramolecular coordination assembly. Temperature dependence of the dc magnetic susceptibility and heat capacity measurements indicate that 1 undergoes an abrupt spin crossover (SCO) with thermal spin transition temperatures of 339 and 337 K for the heating and cooling modes, respectively, resulting in a thermal hysteresis of 2 K. Remarkably, the temperature dependence of dc electrical transport exhibits a transition that coincides with thermal SCO, demonstrating the thermally induced magnetic and electrical bistability of 1 , strongly correlating magnetism with electrical conductivity. This outstanding feature leads to thermally induced simultaneous switching of magnetism and electrical conductivity and a magnetoresistance effect. 相似文献
998.
Mitsuhiro Miyazaki 《代数通讯》2018,46(1):335-355
We define the concept of a doset Hibi ring and a generalized doset Hibi ring which are subrings of a Hibi ring and are normal a?ne semigroup rings. We apply the theory of (generalized) doset Hibi rings to analyze the rings of absolute orthogonal invariants and absolute special orthogonal invariants and show that these rings are normal and Cohen-Macaulay and has rational singularities if the characteristic of the base field is zero and is F-rational otherwise. We also state criteria of Gorenstein property of these rings. 相似文献
999.
Optical Review - Optical pump–probe microscopy can provide images by detecting changes in probe light intensity induced by stimulated emission, photoinduced absorbance change, or... 相似文献
1000.
Li CZ Matsuo Y Niinomi T Sato Y Nakamura E 《Chemical communications (Cambridge, England)》2010,46(45):8582-8584
Treatment of [60]fullerene with potassium methylnaphthalenide and excess C(6)F(5)CH(2)Br afforded 1,4-bis(pentafluorobenzyl)[60]fullerene, the study of which showed that there is a face-to-face interaction between [60]fullerene and a perfluoro aromatic ring, allowing the molecule to be utilized for high-performance organic photovoltaic devices. 相似文献