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21.
Hiroyuki Ohno 《Tetrahedron letters》2006,47(32):5747-5750
The first total synthesis of dapiramicin B, a nucleoside antibiotic, is described. The characteristic N-glycoside linkage in dapiramicin B was effectively constructed by way of the Pd-catalyzed coupling reaction of a heptopyranosylamine with a bromopyrrolopyrimidine derivative. 相似文献
22.
Kyoungmoo Koh Kohji Ohno Yoshinobu Tsujii Takeshi Fukuda 《European Polymer Journal》2004,40(12):2665-2670
Copper-mediated atom transfer radical polymerization (ATRP) of a protected silanol group-holding methacrylate, methacryloxypropyltrimethoxysilane (MOPS), was investigated. In a dry condition using carefully distilled solvent and monomer, the polymerization proceeded in a living fashion providing a low-polydispersity polymer with a predicted molecular weight. The ATRP in conjunction with the sequential monomer addition of methyl methacrylate (MMA) and MOPS afforded a block copolymer of the type PMMA-b-poly(MMA-r-MOPS). The heat treatment of a solution of the block copolymer in the presence of a catalytic amount of ammonia gave a polymeric core-shell nanoparticle with a shell of PMMA moieties and a core of the poly(MMA-r-MOPS) blocks cross-linked via the condensation of the trimethoxysilane groups of the MOPS moieties. 相似文献
23.
The chemical cross-linking of soluble (1----3)-beta-D-glucans having molecular weights of 21000 (CL 3 h) and 6400 (CL 6 h), and laminarin (CL LAMI), which showed negligible biological activity, by epichlorohydrin provided rigid particles. These particles showed no gel-to-sol transition upon the addition of sodium hydroxide. We compared the effects of chemical cross-linking on the biological activities of glucans. The alternative complement pathway was not activated by any of the cross-linked glucans. Glucose consumption, lysosomal enzyme release, and interleukin-1 production by mouse resident peritoneal macrophages incubated in vitro were strongly induced by CL 3 h, CL 6 h and CL LAMI. However, cross-linked dextran, Sephadex, did not exhibit any of these biological activities. These results suggested that chemical cross-linking of (1----3)-beta-D-glucans enhances macrophage activities without opsonization by complement components. 相似文献
24.
Hamao Umezawa Tomohisa Takita Yukio Sugiura Masami Otsuka Susumu Kobayashi Masaji Ohno 《Tetrahedron》1984,40(3):501-509
Biosynthetic intermediates and synthetic analogues of bleomycin (BLM) have been investigated for their metal binding, dioxygen activation, and DNA cleavage. Molecular O2 was activated by the Fe(II) complex of a synthetic model ligand. Nucleotide sequence specificities in DNA cleavage by the BLM-Fe(II) and deglyco-BLM-Fe(II) complexes were almost identical. It has been shown that (1) the β-aminoalanine-pyrimidine-β-hydroxyhistidine portion of BLM is essential for the metal binding and dioxygen activation and (2) the bithiazole moiety contributes to the specific binding to guanine base of DNA. 相似文献
25.
Koichi Ohno 《Chemical physics letters》1980,69(3):491-494
Upper and lower bounds of the vibrational sums involved in the polanzability tensor are derived. The lower bound leads to a simplified formula applicable to resonance Raman scattering in both weak and strong coupling cases. A new expansion of the vibrational sum is introduced and useful expressions for excitation profiles are obtained. 相似文献
26.
Ananya Banik Theodosios Famprikis Michael Ghidiu Saneyuki Ohno Marvin A. Kraft Wolfgang G. Zeier 《Chemical science》2021,12(18):6238
The development of high-performance inorganic solid electrolytes is central to achieving high-energy- density solid-state batteries. Whereas these solid-state materials are often prepared via classic solid-state syntheses, recent efforts in the community have shown that mechanochemical reactions, solution syntheses, microwave syntheses, and various post-synthetic heat treatment routines can drastically affect the structure and microstructure, and with it, the transport properties of the materials. On the one hand, these are important considerations for the upscaling of a materials processing route for industrial applications and industrial production. On the other hand, it shows that the influence of the different syntheses on the materials'' properties is neither well understood fundamentally nor broadly internalized well. Here we aim to review the recent efforts on understanding the influence of the synthetic procedure on the synthesis – (micro)structure – transport correlations in superionic conductors. Our aim is to provide the field of solid-state research a direction for future efforts to better understand current materials properties based on synthetic routes, rather than having an overly simplistic idea of any given composition having an intrinsic conductivity. We hope this review will shed light on the underestimated influence of synthesis on the transport properties of solid electrolytes toward the design of syntheses of future solid electrolytes and help guide industrial efforts of known materials.Influence of synthesis and processing on the nature of ultimate product and the ionic transport properties of superionic conductors. 相似文献
27.
The reactions of α-silyloxy-ga,β-unsaturated ketone and aldehyde with diene afforded [4+2] and [4+3] cycloadducts respectively in the presence of a catalyst. 相似文献
28.
Sahara R Ichikawa H Mizuseki H Ohno K Kubo H Kawazoe Y 《The Journal of chemical physics》2004,120(19):9297-9301
A Monte Carlo simulation is carried out to study thermodynamic properties of Cu-Au alloys using a face-centered-cubic (fcc) lattice-gas model. To obtain quantitatively accurate results, a Finnis-Sinclair-type potential, which has been widely used for molecular dynamics (MD) simulations, is employed. To overcome some shortcomings of lattice-gas models such as neglecting vibrational entropy, the potential is mapped onto the fcc lattice using the renormalization technique. The renormalized potential gives an improved Cu-Au phase diagram compared to the original MD potential applied directly on the lattice. 相似文献
29.
Yoshinori Tominaga Syuichirou Ohno Shinya Kohra Hiroshi Fujito Hisako Mazurae 《Journal of heterocyclic chemistry》1991,28(4):1039-1042
N-Bis(methylthio)methylenecyanamide ( 1 ) was allowed to react with active methylene compounds (methyl cyanoacetate, dimethyl malonate, ethyl acetoacetate, ethyl phenylacetate) in the presence of potassium carbonate or potassium hydroxide in dimethyl sulfoxide followed by the treatment using appropriate a base or an acid to give the corresponding 6-methylthiouracil derivatives in 15–80% yields. These uracil derivatives are found to be useful intermediates for the synthesis of 6-aminouracils and fused pyrimidine derivatives. 相似文献
30.