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531.
Dibenz[c,h]acridine ( 13 ) was formed directly by the Chapman rearrangement of 2-methoxycarbonyl-1-naphthyl-N-1′-naphthylbenzimidate ( 11 ) without isolation of intermediate 12 . When the Chapman rearrangement was carried out under mild reaction conditions, the intermediate 12 was isolated in high yield, whose structure was determined by the X-ray studies. The mechanism of the Chapman rearrangement can be interpreted on the basis of the X-ray data of 11 and 12 . 相似文献
532.
Sigeru Torii Hideo Tanaka Norio Saitoh Takashi Siroi Michio Sasaoka Junzo Nokami 《Tetrahedron letters》1982,23(21):2187-2188
Synthesis of 3-chloromethyl-Δ3-cephems from 4-arenesulfonylthioazetidin-2-ones , derived from penicillins G and V, has been achieved by the electrolytic ene-type chlorination of in a CHC13-aqueous NaCl-H2SO4-(Pt electrodes) system and subsequent ring closure with NH3 in DMF. 相似文献
533.
A new hierarchy of solvable IRF models is presented. It is generated from Belavin's Z
n
×Z
n
symmetric model. The site variables take values in the set of level l dominant integral weights of A
–1
(1)
. It is conjectured that the local state probabilities are given through the irreducible decomposition of characters for the affine Lie algebra pair (A
n–1
(1)
A
n–1
(1)
,A
n–1
(1)
). 相似文献
534.
The well‐defined polystyrene‐block‐poly(4‐vinylpyridine) [PS‐block‐P4VP (SV1); lamellar morphology] and polyisoprene‐block‐poly(α‐methyl styrene) [PI‐block‐PMS (IMS1); PI spherical morphology] diblock copolymers were prepared by sequential anionic polymerization techniques. The segregated chains in the P4VP lamellar layers of the SV1 film (PS lamellae: 41 nm; P4VP lamellae: 51 nm) were crosslinked with 1,4‐dibromobutane. This crosslinked film was insoluble in organic solvents such as benzene and chloroform (CHCl3) and exhibited various structural colors under the swollen state. The IMS1 film (body‐centered cubic lattice, diameter of PI spheres: 53 nm) was soaked in the mixture of CHCl3/hexane (1 : 10, v/v). This solvent system resulted in the swelling of PI spherical domains. The transmitted and reflected light color through the swollen film changed to a deep blue. Such color changes were reversible upon swelling in solvent and evaporation of the solvent. Subsequently, photofunctional diethyldithiocarbamate (DC) groups were introduced into the PS block of the parent block copolymer IMS1 by means of polymer reactions. The locking of the cubic lattice was performed with living radical graft copolymerization from DC groups of swollen as‐cast film in methyl methacrylate (MMA) under UV irradiation. The locking of structural colors such as blue and green was also achieved, varying the content of poly(methyl methacrylate) (PMMA) grafted chains. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
535.
Hongwei Liu Teruaki Nishikawa Kazuo Tachibana Hiroshi Nagai Michio Namikoshi 《Tetrahedron letters》2004,45(38):7015-7017
A novel tribenzotetrathiepin alkaloid, named lissoclibadin 1 (1), has been isolated from the ascidian Lissoclinum sp. (cf. L. badium Monniot and Monniot, 1996). The gross structure was assigned on the basis of the spectral data, and one of two possible isomers was selected by the computational modeling study. Lissoclibadin 1 inhibited the growth of the marine bacterium Ruegeria atlantica (15.2 mm at 20 μg/disk). 相似文献
536.
Kohji Yoshinaga Ryouhei Horie Futoshi Saigoh Taketoshi Kito Naoyuki Enomoto Hiroyasu Nishida Michio Komatsu 《先进技术聚合物》1992,3(2):91-93
The reaction of monodispersed silica colloid with hydrophobic and hydrophilic polymer coupling agents in the presence of ammonia afforded dispersible polymer/SiO2 composites into organic solvents without aggregation. 相似文献
537.
Ascorbic acid (AA) could be determined in large quantities of a co-existing oxidant. The incorporation of an on-line reagent regeneration step based on redox reaction eliminates the baseline drift in the procedure. This makes it possible to adopt a circulatory flow injection method (cyclic FIA) and to determine AA repetitively. The method is based on the reduction of iron(III) to iron(II) by the analyte, the reaction of the produced iron(II) with 1,10-phenanthroline (phen) in a weak acidic medium to form a colored complex, and the subsequent oxidation reaction of iron(II) to iron(III) by the co-existing peroxodisulfate. A solution (50 ml) of 3.0×10−4 mol l−1 ferric chloride, 9.0×10−4 mol l−1 phen and 5.0×10−2 mol l−1 ammonium peroxodisulfate in acetate buffer (0.2 mol l−1, pH 4.5) is continuously circulated at a constant flow rate of 1.0 ml min−1. Into this stream, an aliquot (20 μl) of the sample solution containing AA is quickly injected by means of a six-way valve. The complex formed is monitored spectrophotometrically (at 510 nm) in the flow system. The stream then returns to the reservoir after passing through a time-delay coil (50 m). The iron(II)–(phen)3 complex is oxidized to iron(III)–(phen)3 complex by peroxodisulfate which exists excessively in the circulating reagent solution. The proposed method allows as many as 300 repetitive determinations of 15 mg l−1 AA with only 50 ml reservoir solution. The contents of AA in commercial pharmaceutical products were analyzed to demonstrate the capability of the developed system. 相似文献
538.
Michio Obayashi Kiitiro Utimoto Hitosi Nozaki 《Journal of organometallic chemistry》1979,177(1):145-152
The alkylcopper reagents prepared from RMgBr and CuBr react with trimethylsilylacetylene to give regio- and stereo-selectivity 1-trimethylsilyl-1(Z)-alkenylcopper adducts. Hydrolysis affords 1-trimethylsilyl-1(E)-alkenes exclusively. Alkylation, acylation, halogenation, and stannylation proceed stereoselectively to afford synthetically useful intermediates. Homopropargylation of alkyl 1-trimethylsilyl-1(Z)-alkenylcuprates provided better yield than that of the original vinylcopper reagents. 相似文献
539.
Toshiyuki Kodaira Quing-Quing Liu Michio Urushisaki 《Journal of polymer science. Part A, Polymer chemistry》1995,33(16):2681-2690
N,N-Diallylmethacrylamide (DAMA) was synthesized and its radical cyclopolymerizability was investigated. Polymerizations of DAMA were found to proceed according to the standard kinetic equation for radical polymerization except for the diffusion controlled termination reactions owing to higher viscosity of DAMA, in spite of the fact that it contains two allyl groups. DAMA yields polymers with slightly higher degree of cyclization than 50% in dilute solution polymerization. With increasing monomer concentration, the degree of cyclization decreases gradually and it becomes slightly lower value than 50% in concentrated solution polymerizations. It was found that about 86% of pendant unsaturations is allyl group and the rest is methacryloyl group. Structural studies on repeating units showed that possibility for the presence of bicyclic structures (those formed with consumption of three double bonds involved in DAMA) and structural units with two pendant unsaturations (those formed with one double bond in DAMA participated in polymerization) is extremely small. Main repeating cyclic unit was assigned to five-membered monocyclic lactam with an allyl group on its nitrogen, the content of which is estimated to be approximately 86% based on the allyl content. The main fraction of the rest of repeating cyclic structures was attributed to monocyclic pirolidine ring with a methacryloyl group on its nitrogen. These structural investigations and ESR studies of DAMA revealed that the methacryloyl group of DAMA is less reactive than its allyl group as in the case of N-methyl-N-allylmethacrylamide which has already been reported. © 1995 John Wiley & Sons, Inc. 相似文献
540.
Shoji Ando Haruhiko Aoyagi Michinori Waki Tetsuo Kato Nobuo Izumiya Kouji Okamoto Michio Kondo 《Tetrahedron letters》1982,23(21):2195-2198
Gramicidin S (GS) analogs, (D-Ser(Bzl)4,4′]-GS (), [D-Ser4,4′]-GS (), and [L-Orn(Boc)2,2′,D-Ser4,4′]-GS () were synthesized and showed high antibacterial activity. One residue of D-Ser in was converted asymmetrically to D-Ala via α,β-dehydroalanine. 相似文献