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991.
K. Yamashita T. Osaki K. Sasaki H. Yokota N. Oshima M. Nango K. Tsuda 《Journal of polymer science. Part A, Polymer chemistry》1994,32(9):1711-1717
We characterized three low-molecular-weight thiazolium salt analogues: N-methyl-5-(2′-benzyloxyethyl)-4-methylthiazolium iodide (MBMTI), N-methyl-4-phenylthiazolium iodide (MPTI), and N-methylbenzothiazolium iodide (MBTI). MBMTI, having high-electron density on the thiezolium ring, was found to be a durable thiazolium salt in buffer solution. Then, the polymer-supported thiazolium salt catalyst having MBMTI structure as a catalytic site for acyloin condensation was prepared by the polymerization of the corresponding thiazole monomer and the following quaternization. The polymer catalyst had excellent catalytic activity even in buffer solution, while the corresponding low molecular weight catalyst did not show any activity in aqueous system. Furthermore, the durable polymer catalyst could be reused under the aqueous condition. © 1994 John Wiley & Sons, Inc. 相似文献
992.
Hiroji Oda Yoshitomi Morizawa Koichiro Oshima Hitosi Nozaki 《Tetrahedron letters》1984,25(30):3217-3220
The reaction of terminal acetylenes with (Ph3Ge)2Cu(CN)Li2 (1) or (Et3Ge)2Cu(SMe2)Li (2) provides vinylgermanes in good yields. Whereas germylcupration of 1-dodecyne gives 2-germyl-1-dodecene as a main product, germylmetalation of phenylacetylene or 3-methyl-3-buten-1-yne affords 1-germyl compounds preferentially. 相似文献
993.
Kakiya H Yagi K Shinokubo H Oshima K 《Journal of the American Chemical Society》2002,124(31):9032-9033
A convergent synthesis of a pyrimidine core has been achieved. Treatment of alpha,alpha-dibromo oxime ethers, which are easily derived from the corresponding esters, with a variety of Grignard reagents provides trisubstituted pyrimidines in good yields. This new method offers an easy access to functionalized pyrimidines. 相似文献
994.
T Oshima K Sagara Y Y Tong G Zhang Y H Chen 《Chemical & pharmaceutical bulletin》1989,37(9):2456-2458
A new ion-pair high-performance liquid chromatographic method for the analysis of hyoscyamine and scopolamine in various kinds of crude drugs derived from solanaceous plants was evaluated using sodium dodecyl sulfate as a counter ion. A reversed-phase chromatographic system consisting of a chemically bonded ODS silica gel column with phosphate buffer (pH 2.5)-acetonitrile (65:35) containing 17.5 mM sodium dodecyl sulfate as the mobile phase was used. Hyoscyamine and scopolamine in crude drugs derived from Scopolia, Atropa, Hyoscyamus and Datura species were separated from other compounds in the crude drugs and determined within 20 min after direct injection of the solution extracted with the mobile phase. The results for various kinds of samples are presented. 相似文献
995.
[reaction: see text] The BF(3)-catalyzed rearrangement of cyclobutene-fused m- and p-substituted diarylhomobenzoquinones exclusively gave the keto-alcohols via a Wagner-Meerwein vinyl-anion migration followed by the annulation of a delta-located endo-aryl group. The Hammett treatments for the endo/exo substituent effects, as well as the kinetic solvent effects, indicated that this reaction proceeds through the concerted S(N)2-like mechanism involving a rate-determining endo-aryl-assisted transition state. 相似文献
996.
Taichi Abe Kazuteru Shinozaki Noriaki Ikeda Takayoshi Suzuki 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):m456-m458
In the title compound, [Pt(C18H15N2)Cl], the PtII centre adopts a distorted square‐planar coordination geometry due to the pincer‐type monoanionic N–C–N tridentate ligand. The planar complexes stack viaπ–π interactions to form two‐dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer‐type N–C–N complexes, which exhibit a one‐dimensional columnar stacking. 相似文献
997.
R. Oshima T. Wada J. Kumanotani 《Journal of polymer science. Part A, Polymer chemistry》1984,22(11):3135-3147
Poly(L -cysteine derivative)s containing carbazole groups in the side chains separated from the backbone by several distances have been synthesized. It is revealed by measuring the IR spectra that they assume the antiparallel-chain pleated sheet (β-conformation) in the solid films independent of side chain length. DSC thermograms, and CD and fluorescence spectra of the films of these polymers are also presented in relation to the alignment of side-chain carbazole groups. 相似文献
998.
Noriaki Dokoshi Shunroku Tohyama Saburo Fujita Masaru Kurihara Naoya Yoda 《Journal of polymer science. Part A, Polymer chemistry》1970,8(8):2197-2217
Fully aromatic poly(heterocyclic imides) of high molecular weight were prepared by the cyclopolycondensation reactions of aromatic diamines with new monomer adducts prepared by condensing orthodisubstituted aromatic diamines with chloroformyl phthalic anhydrides. The low-temperature solution polymerization techniques yielded tractable poly(amic acid), which was converted to poly(heterocyclic imides) by heat treatment to effect cyclodehydration at 250–400°C under reduced pressure. In this way, the polyaromatic imideheterocycles such as poly(benzoxazinone imides), poly(benzoxazole imides), poly(benzimidazole imides) and poly(benzothiazole imides) were prepared, which have excellent processability and thermal stability both in nitrogen and in air. The poly(amic acids) are soluble in such organic polar solvents as N,N-dimethyl-acetamide, N-methylpyrrolidone, and dimethyl sulfoxide, and the films can be cast from the polymer solution of poly(amic acids) (ηinh = 0.8–1.8). The film is made tough by being heated in nitrogen or under reduced pressure to effect cyclodehydration at 300–400°C. The polymerization was carried out by first isolating the monomer adducts, followed by polymerization with aromatic diamines. On subsequently being heated, the open-chain precursor, poly(amic acid), undergoes cyclodehydration along the polymer chain, giving the thermally stable ordered copolymers of the corresponding heterocyclic imide structure. 相似文献
999.
M. Oshima Y. Toh A. Kimura M. Ebihara Y. Oura Y. Itoh H. Sawahata M. Matsuo 《Journal of Radioanalytical and Nuclear Chemistry》2007,271(2):317-321
By combining neutron activation analysis with multiple gamma-ray detection (gamma-gamma coincidence), we have proved better
sensitivity and resolution for the trace element analysis than the ordinary single gamma-ray detection method. We now try
to apply the multiple gamma-ray detection method to the prompt gamma ray analysis (PGA). We have established a new cold neutron
beam line for PGA in Japan Research Reactor, JRR-3M, at Tokai establishment of Japan Atomic Energy Research Institute (JAERI).
It consists of a beam shutter, a beam attenuator, a gamma-ray detector array, a sample changer, and a beam stopper. We construct
a high-efficiency gamma-ray detector array specially designed for this purpose. Its performance has been evaluated with the
Monte Carlo simulation code, GEANT 4.5.0. 相似文献
1000.