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271.
272.
M Arisawa A Fujita T Hayashi K Hayashi H Ochiai N Morita 《Chemical & pharmaceutical bulletin》1990,38(6):1624-1626
The phloroglucinol derivatives isolated from Mallotus japonicus Muell. Arg. (Euphorbiaceae) and their derivatives were evaluated for their capacity to produce cytotoxicity in HeLa cells and to inhibit the replication of herpes simplex virus type 1 (HSV-1). The characterizations of an isolated new acetophenone, mallophenone (16), and cyclization products of mallotojaponin (1), isomallotochromene (17), mallotochroman (18) and isomallotochroman (19), were also described. All tested derivatives inhibited the replication of HSV-1 with ED50 in the range of 88 ng--48 micrograms/ml. The derivatives 12 and 19 were found in vitro therapeutic index with 10.9 and 9.1, respectively, and they were considered to be active antivirals. 相似文献
273.
Intermolecular transylidations between aryliodonium ylides under catalytic conditions were developed. Heating a solution of phenyliodonium bis(trifluoromethylsulfonyl)methylide in a large amount (80 equiv) of a substituted iodobenzene in the presence of 5 mol % of rhodium(II) acetate as a catalyst transfers the bis(trifluoromethylsulfonyl)-methylidene group to the iodine(I) atom and affords a substituted aryliodonium ylide in a good yield. Reversible nature of the catalytic intermolecular transylidation makes it possible to evaluate the thermodynamic stability of aryliodonium ylides. 相似文献
274.
Ochiai M 《Chemical record (New York, N.Y.)》2007,7(1):12-23
Isolation, characterization, and reaction of the activated iodosylbenzene monomer, hydroxy(phenyl)iodonium ion, as a complex with 18-crown-6 (18C6) are reported. The reaction of iodosylbenzene with HBF(4) in the presence of 18C6 afforded the hydroxy-lambda(3)-iodane complex PhI(OH)BF(4).18C6 as stable yellow prisms. X-ray structure analysis indicated that the close contacts between the iodine(III) and the three adjacent oxygen atoms of 18C6 will be responsible for the increased stability of the complex compared to the uncomplexed PhI(OH)BF(4). The aqua complex of the activated iodosylbenzene, PhI(OH)OTf.18C6.H(2)O, with a water molecule coordinated to iodine(III) was also prepared. These crown ether complexes are highly reactive and serve as versatile stoichiometric oxidants, especially in water. Thus, the complexes undergo oxidative transformations of a variety of functional groups such as olefins, alkynes, enones, silyl enol ethers, sulfides, and phenols under mild conditions. The latter part reports on the iodobenzene-catalyzed alpha-oxidation of ketones, in which diacyloxy(phenyl)-lambda(3)-iodanes generated in situ act as real oxidants of ketones and m-chloroperbenzoic acid (m-CPBA) serves as a terminal oxidant. The oxidation of a ketone with m-CPBA in acetic acid in the presence of a catalytic amount of iodobenzene, BF(3)-Et(2)O, and water at room temperature affords an alpha-acetoxy ketone in good yield. It is noted that the use of water and BF(3)-Et(2)O is crucial to the success of this alpha-acetoxylation. 相似文献
275.
276.
Chenxi Zhang Bungo Ochiai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(12):2643-2649
Oligomer samples obtained by the anionic copolymerization of a bis(γ‐lactone), 2,8‐dioxa‐1‐methylbicyclo[3.3.0]octane‐3,7‐dione ( 1 ), and glycidyl phenyl ether with potassium tert‐butoxide have been analyzed by matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry. The MALDI‐TOF mass spectra of these cooligomers show well‐resolved signals that can be reliably assigned to linear, alternating cooligomers that have carboxylate chain ends or alkoxide chain ends and cyclic ones. The formation of these three series of cooligomers suggests that the polymerization process involves concomitant intermolecular transesterification and intramolecular back‐biting. The intramolecular back‐biting reaction causes the formation of cyclic cooligomers, whereas the intermolecular transesterification causes the reduction of the molecular weight and the transformation of the alkoxide active chain end into a carboxylate chain end. The MALDI‐TOF mass spectrometry study has shown that an excess of monomer 1 enhances the selectivity of propagation by increasing the probability of the attack of the alkoxide chain end to 1 . © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2643–2649, 2005 相似文献
277.
S. Uchino S. Hashii T. Kato N. Aoki K. Horiuchi M. Shimizu Y. Ochiai 《Superlattices and Microstructures》2003,34(3-6):395
Low temperature transport in C60 thin film field-effect transistors has been studied using several samples with various gate voltages. Nearest neighbor hopping and variable range hopping transport have been observed in the low temperature transport measurements. Analyzing the temperature dependence of the transport types, it was found that the electrical properties of the film can be improved by thermally agitated evaporation of C60. 相似文献
278.
Bungo Ochiai Tokinori Iwamoto Toyoharu Miyagawa Daisuke Nagai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2004,42(15):3812-3817
Carbon dioxide was incorporated into poly(glycidyl methacrylate‐co‐methyl methacrylate) by a solid‐phase reaction, which transformed the pendent oxirane moieties into cyclic carbonate moieties, with quaternary ammonium halide catalysts. The incorporation of carbon dioxide into the copolymer led to soluble carbonate‐containing polymers, whereas the incorporation of carbon dioxide into the glycidyl methacrylate homopolymer produced an insoluble product. The copolymer composition, reaction temperature, and catalyst amount affected the incorporation efficiency and the side reaction that caused crosslinking. Effective incorporation was achieved under the following reaction conditions: the glycidyl methacrylate content was less than approximately 50%, the temperature was greater than the glass‐transition temperature, and the catalyst concentration was 1.5–6 mol %. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3812–3817, 2004 相似文献
279.
T. Kuroda T. Mano T. Ochiai S. Sanguinetti T. Noda K. Kuroda K. Sakoda G. Kido N. Koguchi 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):46
Quantized energy levels of nanoscopic concentric double rings are identified by means of micro photoluminescence spectroscopy. High-yield emissions from a single quantum structures are observed. The spectra show several discrete lines reflecting the carrier confinement in the rings. Effective mass calculation is performed to characterize the quantized motion of carriers with rotational and orbital degrees of freedoms. Excellent agreement between the observed spectra and the numerical ones is found. 相似文献
280.
Teruaki Sakurai Masayuki Ochiai Chikara Kojima Takami Ohta Kitao Fujiwara 《应用有机金属化学》2005,19(2):226-230
In this study, we observed the first in vivo acute immunotoxicity of a trimethyl(2‐hydroxyethyl)arsonium cation, namely arsenocholine (AsCho), which is present in marine animals that are ingested daily as seafood in many countries. It has been reported that AsCho has significant acute in vivo toxicity. A high dose of the synthetic pure AsCho was administered to CDF1 mice intraperitoneally (0.1 g kg?1 mouse weight) or orally (a total of 10.0 g kg?1 mouse weight); its effect on the immune organs and immune effector cells was assessed. Administered AsCho, especially via the oral route, showed weak and partial, but significant, in vivo immunotoxicity in mice, although it did not cause any severe acute inflammatory responses. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献