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排序方式: 共有195条查询结果,搜索用时 15 毫秒
11.
Junzo Otera Masaki Kishi Koichi Kanehira Shigeaki Suzuki Manzo Shiono Yoshiji Fujita 《合成通讯》2013,43(4):347-352
A sequence of ene-type chlorination, palladium catalyzed dehydrochlorination, and the intramolecular Diels-Alder reaction afforded a new method for conversion of prenyl derivatives into bicyclic compounds. 相似文献
12.
Unsaturated nitriles have been synthesized from trisubstituted olefins via ene-type chlorination and regioselective substitution with cyanide ion followed by double bond migration. 相似文献
13.
Kei Ohkubo Kentaro Mizushima Shunichi Fukuzumi 《Research on Chemical Intermediates》2013,39(1):205-220
Efficient photocatalytic oxygenation of toluene occurs under visible light irradiation of 9-mesityl-10-methylacridinium (Acr+–Mes) in oxygen-saturated acetonitrile containing toluene and aqueous hydrochloric acid with a xenon lamp for 15 h. The oxygenated products, benzoic acid (70 %) and benzaldehyde (30 %), were formed after the photoirradiation. The photocatalytic reaction is initiated by intramolecular photoinduced electron transfer from the mesitylene moiety to the singlet excited state of the Acr+ moiety of Acr+–Mes, which affords the electron-transfer state, Acr?–Mes?+. The Mes?+ moiety can oxidize chloride ion (Cl?) by electron transfer to produce chlorine radical (Cl?), whereas the Acr? moiety can reduce O2 to O 2 ?? . The Cl? radical produced abstracts a hydrogen from toluene to afford benzyl radical in competition with the bimolecular radical coupling of Cl?. The benzyl radical reacts with O2 rapidly to afford the peroxyl radical, leading to the oxygenated product, benzaldehyde. Benzaldehyde is readily further photooxygenated to yield benzoic acid with Acr?–Mes?+. In the case of an aromatic compound with electron-donating substituents, 1,3,5-trimethoxybenzene, photocatalytic chlorination occurred efficiently under the same photoirradiation conditions to yield a monochloro-substituted compound, 2,4,6-trimethoxychlorobenzene. 相似文献
14.
Ryota Moriai Yu-suke Naito Ryosuke Nomura Shigeaki Funyu Ken-ich Ishitsuka Naoki Asano Sentaro Okamoto 《Tetrahedron letters》2014
1,3-Diarylpropenes 9 having a 1,3-dialkoxy-2-methylpropan-2-yl group were designed as tethering monomers for folded H-stacking polymers, and were readily synthesized from 2-ethoxymethylidene malonate in four- or five-steps, including a facile sequential addition–elimination–addition reaction of benzyl zinc reagents. The preference for the closed (stacked) conformation in the resulting 2-substituted 1,3-diarylpropanes 9 was evaluated using MM2 calculations, 1H NMR analyses, and fluorescence measurements. Copolymerization of the resulting monomers 9 with compounds containing π-units provided polymers with blue-shifted UV-absorptions both in solution and as films, compared with that of a model compound containing a single π-unit. This optical property is unique to H-aggregated π-units. 相似文献
15.
Yoshida Keiichiro Ishizuka Tomohiro Mizushima Chiharu Nishidate Izumi Kawauchi Satoko Sato Shunichi Sato Manabu 《Optical Review》2015,22(2):374-384
Optical Review - To evaluate multi-spectral images of the absorption and scattering properties in the cerebral cortex of rat brain, we investigated spectral reflectance images estimated by the... 相似文献
16.
Takahiro Miyata Kozo Matsumoto Takeshi Endo Shigeaki Yonemori Shoji Watanabe 《Journal of polymer science. Part A, Polymer chemistry》2012,50(15):3046-3051
A styrene‐based monomer having a five‐membered cyclic carbonate structure, 4‐vinylbenzyl 2,5‐dioxoran‐3‐ylmethyl ether (VBCE), was prepared by lithium bromide‐catalyzed addition of carbon dioxide to 4‐vinylbenxyl glycidyl ether (VBGE). Radical polymerization of the obtained VBCE was carried out using 2,2′‐azobisisobutyronitrile as an initiator. PolyVBCE with number‐averaged molecular weight higher than 13,800 was obtained by a solution polymerization in N,N‐dimethylformamide, N,N‐dimethylacetamide, dimethyl sulfoxide, and methyl ethyl ketone. The glass transition temperature and 5 wt % decomposition temperature of the polyVBCE were determined to be 52 and 305 °C by differential scanning calorimetry and thermal gravimetry analysis, respectively. It was confirmed that a polymer consisting of the same VBCE repeating unit can be also obtained via chemical modification of polyVBGE, that is, a lithium‐bromide‐catalyzed addition of carbon dioxide to a polyVBGE prepared from a radical polymerization of VBGE. Further copolymerization of VBCE with styrene gave the corresponding copolymer in a high yield. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献
17.
The Mermin-Ho and Anderson-Toulouse coreless vortices are demonstrated to be thermodynamically stable in ferromagnetic F = 1 spinor Bose-Einstein condensates under rotation. We have carried out extensive calculations of the Gross-Pitaevskii equations by assuming uniform density along the z axis and comparing the energies of other competing non-axis-symmetric or singular vortices. The phase diagram is thereby established in a plane of the rotation drive vs the total magnetization. Their stability is also checked by calculating collective modes based on the Bogoliubov equations. 相似文献
18.
Noboru Mizushima 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2007,83(2):39-46
Autophagy is in principle a non-selective degradation system within cells, which is conserved in all eukaryotic cells. Autophagy is usually suppressed at low levels but can be upregulated during periods of nutrient starvation, which facilitates cell survival. In addition to this fundamental role, basal autophagy was recently revealed to be important for constitutive turnover of intracellular proteins and organelles. Autophagy has been considered to be involved also in presentation of endogenous antigens, degradation of invasive bacteria, tumor suppression, cell death and development. This review will discuss the biological significance of autophagy, particularly focusing on its implications in protein metabolism in mammals. 相似文献
19.
A 5-amino-8-hydroxyquinoline (AHQ)-modified gold nanoparticle (GNP) layer was fabricated on an inner wall of a silica capillary column by alternatively passing a citrate-stabilized GNP solution and an AHQ solution in a repeating fashion. The observations by a field emission scanning electron microscope showed that the thickness of the resulting GNP layer was about 0.15 microm. This column was then used as an open tubular solid-phase extraction column for cadmium, followed by electrothermal atomic absorption spectrometric determination. The detection limit of 0.009 ng ml(-1) was obtained. 相似文献
20.