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71.
Hiroshi Nagai Minami Watanabe Shingo Sato Mioko Kawaguchi Yue-Yun Xiao Kazutaka Hayashi Ryuichi Watanabe Hajime Uchida Masayuki Satake 《Tetrahedron》2019,75(17):2486-2494
The marine cyanobacterium Moorea producens is a rich source of diverse compounds that possess a variety of biological activities. In the present study, eight new aplysiatoxin derivatives, namely 6, 8–13, and 15, along with aplysiatoxin (1), debromoaplysiatoxin (2), 3-methoxyaplysiatoxin (3), anhydroaplysiatoxin (4), anhydrodebromoaplysiatoxin (5), oscillatoxin B2 (7), and 30-methyloscillatoxin D (14) were isolated and identified from the Okinawan M. producens. In cytotoxicity and diatom growth inhibition tests, the fifteen compounds tested (1–15) showed moderate or no activity at a concentration of 10?μg/mL. 相似文献
72.
Dr. Yogesh Kumar Maurya Dr. Pingchun Wei Takahide Shimada Dr. Kazuhisa Yamasumi Dr. Shigeki Mori Prof. Dr. Ko Furukawa Dr. Hajime Kusaba Prof. Dr. Tatsumi Ishihara Prof. Dr. Yongshu Xie Dr. Masatoshi Ishida Prof. Dr. Hiroyuki Furuta 《化学:亚洲杂志》2021,16(7):743-747
A facile synthetic strategy towards conformationally stable chiral chromophores based on dimeric porphyrinoids has been established. A peculiar class of face-to-face intramolecularly interlocked corrole dimers were formed by the oxidative C−C coupling linked at the inner carbon sites upon simple treatment of copper(II) ions. Their intrinsic electronic structures were modulated by the peripheral corrole ring annulations, which lead to distinct optical properties and redox profiles. The stereogenic carbon centers implemented in the confused corrole skeleton provided a rationale for designing novel chiral materials. 相似文献
73.
Two series of nano-sized N-containing MOx–ZnO (M: Fe, W) composite powders were synthesized by spray pyrolysis. The nitrogen content was controlled from 500 to 2100 ppm by changing the powder ingredients and spray pyrolysis temperature. Ultraviolet-visible (UV-Vis) spectra indicated that the N-containing MOx–ZnO powders absorbed not only ultraviolet light (λ<387 nm) like pure ZnO powder, but also part of visible light (λ<650 nm). Acetaldehyde decomposition was used as a probe reaction to evaluate the photocatalysis of these composite powders. The photocatalytic activity of the N-containing ZnO powder was pronouncedly enhanced by the WO3 addition under both UV and visible-light irradiation. However, that of the N-containing ZnO powder was suppressed by the Fe2O3 addition. A model of the semiconductor energy-band structure is proposed to explain the enhancement and suppression of photocatalytic activity. 相似文献
74.
Kiyoshi Endo Hajime Tsujikawa Takayuki Otsu 《Journal of polymer science. Part A, Polymer chemistry》1986,24(7):1633-1642
5-Phenyl-2-pentene (5Ph2P) was found to undergo monomer-isomerization polymerization with TiCl3–R3Al (R = C2H5 or i-C4H9, Al/Ti > 2) catalysts to give a polymer consisting of exclusively 5-phenyl-1-pentene (5Ph1P) unit. The geometric and positional isomerizations of 5Ph2P to its terminal and other internal isomers were observed to occur during polymerization. The catalyst activity of alkylaluminum examined to TiCl3 was in the following order: (C2H5)3Al > (i-C4H9)3Al > (C2H5)2AlCl. The rate of monomer-isomerization polymerization of 5Ph2P with TiCl3–(C2H5)3Al catalyst was influenced by both the Al/Ti molar ratio and the addition of nickel acetylacetonate [Ni(acac)2], and the maximum rate was observed at Al/Ti = 2.0 and Ni/Ti = 0.4 in molar ratios. 相似文献
75.
Hayashi K Kujime E Katayama H Sano S Nagao Y 《Chemical & pharmaceutical bulletin》2007,55(12):1773-1775
In the imine aldol reactions of 1 with aromatic aldehydes using magnesium salts in the presence of amines, the threo/erythro ratios of products increased in the order Mg(ClO4)2>MgI2>MgBr2>MgCl2>Mg(OTf)2 and N,N,N',N'-tetramethylethylenediamine (TMEDA)>Et3N. This increase in the threo/erythro ratios of products was estimated to be caused by a retro-imine aldol reaction under thermodynamic control. 相似文献
76.
Prof. Dr. Yasunori Yamamoto Masaaki Yohda Tomohiko Shirai Prof. Dr. Hajime Ito Prof. Dr. Norio Miyaura 《化学:亚洲杂志》2012,7(10):2446-2449
A chiral O‐linked C2‐symmetric bidentate phosphoramidite (Me‐BIPAM) was found to be efficient for the ruthenium‐catalyzed addition of arylboronic acids to isatins. Asymmetric synthesis of 3‐aryl‐3‐hydroxy‐2‐oxindoles by 1,2‐addition of arylboronic acids to isatins was carried out in the presence of [RuCl2(PPh3)3]/(R,R)‐Me‐BIPAM and KF, resulting in an enantioselectivity as high as 90 % ee. It was found that the reaction with N‐protected isatins proceeds with high yields and good enantioselectivities. The best protective groups on the nitrogen atom were different depending on the substituents on the aromatic ring. The use of a N‐benzyl group resulted in excellent enantioselectivities in many substrates compared with other groups. 相似文献
77.
78.
[reaction: see text] A ruthenium catalyst precursor bearing a bulky and electron-donating pentamethylcyclopentadienyl (Cp) ligand, typically CpRuH3(PPh3), mediates hydrosilylation of several 1-alkynes with novel regioselectivity to give preferentially 2-silyl-1-alkenes. 相似文献
79.
80.