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991.
Ho Sik Kim Yoshihisa Kurasawa Chiemi Yoshii Minako Masuyama Atsushi Takada Yoshihisa Okamoto 《Journal of heterocyclic chemistry》1990,27(4):1115-1117
The reaction of the 2-substituted 6-chloroquinoxaline 4-oxides 1a or 1b with 2-fold molar amount of methyl propiolate resulted in the 1,3-dipolar cycloaddition reaction to give 8-chloro-1,3-bismethoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 4a or 8-chloro-1,3-bismethoxycarbonyl-4-(morpholin-4-yl)pyrrolo-[1,2-a]quinoxaline 4b , respectively. Compound 4a or 4b was transformed into 8-chloro-3-methoxycarbonyl-4-(piperidin-1-yl)pyrrolo[1,2-a]quinoxaline 5a or 8-chloro-3-methoxycarbonyl-4-(morpholin-4-yl)pyrrolo[1,2-a]-quinoxaline 5b , respectively. The structure of 4a,b was confirmed by the NOE measurement among the C1 -H , C 2-H and C 9-H proton signals of 5a,b . An additional reaction mechanism was proposed for the ring transformation of isoxazolo[2,3-a]quinoxalines into pyrrolo[1,2-a]quinoxalines. 相似文献
992.
[reaction: see text] A new intramolecular triple cyclization of bis(o-haloaryl)diacetylenes, via dilithiation followed by reaction with chalcogen elements, produces pi-conjugated compounds containing heterole-1,2-dichalcogenin-heterole fused tricyclic skeletons. The subsequent dechalcogenation with copper metal affords a series of thiophene- and selenophene-based heteroacenes. 相似文献
993.
Heimei Yuki Koichi Hatada Koji Ota Ikuya Kinoshita Shunsuke Murahashi Katsuhiro Ono Yoshiyuki Ito 《Journal of polymer science. Part A, Polymer chemistry》1969,7(6):1517-1536
Polymerization of benzyl vinyl ether was carried out by BF3·OEt2, and the effects of polymerization conditions on the stereoregularity of the polymer were studied by NMR analysis. The polymerization at ?78°C in toluene gave a highly isotactic polymer. The isotacticity of the polymer was independent of the catalyst concentration but increased with a decrease in the initial monomer concentration and decreased slightly on raising the reaction temperature. When the polymerizations were carried out in toluene—nitroethane mixtures, a gradual decrease in the isotacticity and a rapid decrease in the molecular weight of the polymer were observed with increasing nitroethane in the solvent. The molecular weight of the polymer was almost constant, regardless of the catalyst concentration, and increased with increasing initial monomer concentration and decreasing polymerization temperature. When the polymerization was performed in toluene at ?78°C with a small amount of water or benzyl alcohol, a linear relationship was found between the reciprocal DP of the polymer and water or benzylalcohol concentration. The mechanisms of the initiation reaction and the stereoregulation in the polymerization were also discussed. 相似文献
994.
[reaction: see text] Bicyclo[4.3.0]nonanes (hydrindanes) and bicyclo[3.3.0]octanes (octahydropentalenes) are easily synthesized by palladium-catalyzed cycloalkenylations. Additionally, benzo-fused bicyclo[3.3.0]octanes are prepared for the first time through intramolecular coupling between silyl enol ethers and aromatic rings in the presence of catalytic palladium acetate. 相似文献
995.
996.
In a previous paper, we proposed the infinite sublayer quark model, in which there exists an infinite number of quarksu
and antiquarksu
c
at an infinite sublayer level. By applying the standard model of the electroweak interactions to the weak isospin doublet (u
,u
c
)
T
it is shown that there exists only one gauge fieldW
µ
3
, from which the electromagnetic fieldA
µ=W
µ
3
cos
w
and the neutral vector boson fieldZ
µ
0
=W
µ
3
sin
w
are derived. 相似文献
997.
998.
Experimental study of color degree of freedom of gluons in e+e- annihilation at sqrt s around 60 GeV
Abe K Amako K Arai Y Asano Y Chiba M Chiba Y Daigo M Emura T Fukawa M Fukui T Fukushima Y Haba J Hemmi Y Higuchi M Hirose T Hojyo Y Homma Y Hoshi Y Ikegami Y Ishihara N Kamitani T Kanematsu N Kanzaki J Kikuchi R Kondo T Korhonen TT Koseki T Kurashige H Matsui T Minami M Miyake K Mori S Nagashima Y Nakamura T Nakano I Narita Y Odaka S Ogawa K Ohama T Ohsugi T Okamoto A Ono A Oyama T Sakamoto H Sakuda M Sasao N Sato M Shioden M Shirai J Shirakata M Sugimoto S Sumiyoshi T Suzuki A Suzuki Y 《Physical review letters》1991,66(3):280-284
999.
1000.
Eiji Higuchi Kenichi Okamoto Kenji Miyatake Hiroyuki Uchida Masahiro Watanabe 《Research on Chemical Intermediates》2006,32(5):533-542
Gas diffusion electrodes for high temperature polymer electrolyte fuel cells (PEFCs) have been prepared by using a novel proton
conductive sulfonated polyimide (SPI) electrolyte. The catalyst layer was composed of Pt-loaded carbon black (Pt-CB) and SPI
ionomer. The polarization properties and the microstructure of the catalyst layer were investigated as a function of the SPI/CB
weight ratio. The anodic polarization was found to be negligibly small for all the compositions examined. The highest cathode
performance was obtained at SPI/CB = 0.5 (by weight), where the best balance of high catalyst utilization and oxygen gas diffusion
rate through the ionomer was obtained. 相似文献