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991.
Hafnium(IV) tetratriflate was shown to be an effective catalyst for the regioselective reductive benzylidene ring opening with concurrent silylation reaction. The synthetic conditions were optimized, and the scope and limitations were identified. In addition to glucose and glycosamine derivatives, mannose and galactose were successfully employed as substrates. Various protecting groups such as acetyl, allyl, and benzyl were found to be stable under the reaction conditions. By using a deuterated reducing reagent, the reaction was deduced to proceed via an SN1 mechanism. 相似文献
992.
Nanoparticles of various elements such as Si, Al, and Zr were formed by plasma-induced cathodic discharge electrolysis in
molten chloride electrolyte under a 1 atm Ar atmosphere. Al and Si nanoparticles with 100 nm diameters were obtained from
an LiCl-KCl-CsCl melt at 300°C. Zr nanoparticles with diameters less than 50 nm were obtained from an LiCl-KCl at 450°C. Then
with a newly designed and constructed “rotating disk anode type electrolytic cell”, Ti nanoparticles with diameters less than
20 nm were obtained. Finally, to find more appropriate condition for obtaining finer and more uniform nanoparticles, the effects
of the pulse conditions of the applied current and the rotating velocity of a disk anode on size and morphology among the
obtained nanoparticles were investigated by choosing Ni nanoparticle formation as an example. The results showed that quick
removal of the formed fine nanoparticles from the melt surface, where the discharge column is standing, is the most important
factor to obtain smaller and more uniform nanoparticles. 相似文献
993.
Yuko Takao Tomoaki Masuoka Koji Yamamoto Tadashi Mizutani Fukashi Matsumoto Kazuyuki Moriwaki Koichi Hida Toshiyuki Iwai Takatoshi Ito Takumi Mizuno Toshinobu Ohno 《Tetrahedron letters》2014
Novel fluorinated subnaphthalocyanine derivatives were newly designed and synthesized as donor materials for low molecular organic photovoltaic cells using fullerene as an acceptor. They were designed to have the low-lying HOMO energy levels for improvement of open circuit voltage without any expense of short-circuit current density. The HOMO/LUMO energy levels of hexafluoro-, heptafluoro-, dodecafluoro-, tridecafluoro- and the parent subnaphthalocyanine estimated based on the photoelectron spectroscopy were −5.69/−3.93, −5.67/−3.90, −5.96/−4.19, −5.92/−4.11 and −5.30/−3.58 eV, respectively, showing that frontier orbital energy levels can be effectively tuned by fluorination. 相似文献
994.
995.
Hide-Ki Ishida Hiromune Ando Hiromi Ito Hideharu Ishida Makoto Kiso Akira Hasegawa 《Journal of carbohydrate chemistry》2013,32(4-5):413-428
Abstract A first total synthesis of gangliosides GD1c and GT1a containing Neu5Acα(2→8) Neu5Acα(2→3)Gal residue in their non-reducing terminal is described. Condensation of methyl O-[methyl 5-acetamido-8-O-(5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylono-11,9-lactone) -4,7- di-O-acetyl-3,5-dideoxy-D-glycero-α-D-galcto-2-nonulopyranosyranosylanate]-(2→3)-2,4,6-tri-O-benzoyl-1-thio-β-D-gala-ctopyranoside (1) with 2-(trimethylsilyl)ethyl O-(2-acetamido-4,6-O-benzylidene-2-deoxy-β-D-galactopyranosyl)- (1→4) -O -(2,3,6-tri-O-benzyl-β-D-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (2) or 2-(trimethylsilyl)ethyl O-(2-acetamido-6-O-benzyl-2-deoxy-β-D-galactopyranosyl)-(1→4)-(9-[methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)]-O-(2,6-di-O-benzyl-β-D-galactopyranosyl) - (1→4) - 2,3,6-tri-O-benzyl-β-D-glucopyranoside (3) in the presence of dimethyl(methylthio)sulfonium triflate (DMTST) gave the corresponding hexa-and heptasaccharide derivatives 4 and 5, respectively. These oligosaccharides were converted into the α-trichloroacetimidates 10 and 11 via reductive removal of the benzyl groups and/or benzylidene group, O-acetylation, selective removal of the 2-(trimethylsilyl)ethyl group and treatment with trichloroacetonitrile, which, on coupling with 2-azidosphingosine derivatives 12 or 13, gave the β-glycosides 14 and 15, respectively. Finally, 14 and 15 were transformed, via selective reduction of the azido group, coupling with octadecanoic acid and removal of all protecting groups, into the title gangliosides GD1c 18 and GT1a 19. 相似文献
996.
Makoto Ito 《Few-Body Systems》2013,54(1-4):527-530
The generalized two-center cluster model (GTCM), which can handle various single particle configurations in general two center systems, is applied to the light neutron-rich system, 12 Be = α + α +4N. We discuss the change of the neutrons’ configuration around two α as a variation of an excitation energy. The covalent, ionic and atomic configurations coexists with the degenerate feature above the α +8 He g.s. particle-decay threshold. We find the strong enhancement in the monopole excitation from the ground state to the excited states. The GTCM calculation is also applied to even Be isotopes, and the systematics on the structural changes from bound region to continuum is discussed. 相似文献
997.
Keisuke Sekine Dai Akaishi Kakeru Konagaya Prof. Dr. Shigekazu Ito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(32):e202200657
Optically active cyclopropanes have been widely investigated especially from the views of pharmaceutical and agrochemical industries, and substituting one of the methylenes with the difluoromethylene unit should be promising for developing novel biologically relevant compounds and functional materials. In this paper, the copper-catalyzed enantioselective hydrosilylation of gem-difluorocyclopropenes to provide the corresponding chiral gem-difluorocyclopropanes is presented. The use of copper(I) chloride, chiral ligands including bidentate BINAPs and monodentate phosphoramidites, and silylborane Me2PhSi-Bpin accompanying sodium tert-butoxide in methanol was appropriate for the enantioselective hydrosilylation of the strained C=C double bond, and the resultant chiral difluorinated three-membered ring was unambiguously characterized. Subsequent activation of the silyl groups in enantio-enriched gem-difluorocyclopropanes showed substantial reduction of the enantiopurity, indicating cleavage of the distal C−C bond leading to the transient acyclic intermediates. 相似文献
998.
In this paper, we give an algebro-geometric characterization of Cayley polytopes. As a special case, we also characterize lattice polytopes with lattice width one by using Seshadri constants. 相似文献
999.
Heishi Masaru Shinmei Kenichi Sanjiwa Dasanarayake Althge Rasika Uno Takahiro Kubo Masataka Itoh Takahito 《Ionics》2015,21(1):89-94
Ionics - Polymer electrolytes composed of poly(ethylene oxide) (PEO), lithium oxalate (LiOX), and borontrifluoride diethyl ether (BF3·OEt2) were prepared, and their ionic conductivities,... 相似文献
1000.
Liquid‐Crystalline Biomacromolecular Templates for the Formation of Oriented Thin‐Film Hybrids Composed of Ordered Chitin and Alkaline‐Earth Carbonate
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Dr. Tatsuya Nishimura Ken Toyoda Takahiro Ito Dr. Yuya Oaki Yukiko Namatame Prof. Takashi Kato 《化学:亚洲杂志》2015,10(11):2356-2360
Macroscopically ordered inorganic thin films have been formed on unidirectionally oriented, liquid‐crystalline chitin matrices. In the presence of poly(acrylic acid) (PAA), unidirectionally oriented chitin films act as templates for the formation of oriented thin‐film crystals of alkaline‐earth carbonates such as SrCO3 and BaCO3. The morphology and orientation of crystals are dependent on the metal ion concentration. For SrCO3 crystallization, unidirectional thin films and hexagonal‐shaped thin films have been deposited from 200 and 25 mm concentration strontium solutions, respectively. 相似文献