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51.
Masanari KimuraRyutaro Mukai Naoko TanigawaShuji Tanaka Yoshinao Tamaru 《Tetrahedron》2003,59(39):7767-7777
Without prior activation of allyl alcohols, allylation of a variety of active methylene compounds with allyl alcohols proceeds smoothly at rt-50°C in the presence of catalytic amounts of Pd(OAc)2 (1-10 mol%), Et3B (30-240 mol%), a phosphine ligand (1-20 mol%), and a base (0 to 50-60 mol%). 相似文献
52.
The mechanisms of nitrosation of acetone through sodium enolate [CH3CO1CH2]-Na+ (1) or naked enolate [CH3CO1CH2]- (2) with methyl nitrite CH3O3NO2 (3), and the reactivity of the syn-form of 3 (syn-3) during the C-N bond formation process were investigated using ab initio molecular orbital (MO) methods. Our results have demonstrated the predominant formation of E-1-hydroxyimino-2-oxo-propane CH3COCH=NOH (4E) when the complex [CH3CO1CH2NO2(O3CH3)]-Na+ was produced kinetically via a metal-chelated pericyclic transition state (TS(CHELATED)), in which the O3 atom of syn-3 was coordinated to the Na+ atom of 1. 相似文献
53.
54.
55.
Nabeshima T Tsukada N Nishijima K Ohshiro H Yano Y 《The Journal of organic chemistry》1996,61(13):4342-4350
Synthesis and metal binding properties of thiolariat ethers, where a sulfide side chain is introduced into a framework of a crown ether, have been performed. Remarkably high Ag(+) selectivity among heavy metal ions was observed in solvent extraction and transport across a liquid membrane using thiolariat ethers with a 15-crown-5 ring as carriers. Thiolariat ethers with a 12-crown-4 or a 18-crown-6 do not exhibit such a high Ag(+) selectivity. The former binds metal ions weakly, and the latter recognizes Pb(2+) as well as Ag(+). The corresponding oxygen analogs, i.e. lariat ethers, do not show Ag(+) selectivity. The Ag(+) binding strength of the sulfoxide and sulfone analogs is much lower than that of thiolariat ethers. Thiolariat ethers with a benzocrown framework containing a sulfide chain at the 4 position of the benzene nucleus showed very low affinity to Ag(+). Extractability and transport ability using various thiolariat ether derivatives strongly suggested that this high Ag(+) selectivity is a result of the synergistic coordination of the ring oxygen and the sulfur atom of the thiolariat ether. NMR chemical shifts of protons and carbons in the proximity of the sulfur atom of the thiolariat ether were changed significantly in accordance with the synergistic coordination described above. 1:1 Complexation between a thiolariat ether and Ag(+) were supported by a Job plot using the chemical shift of the methylene protons adjacent to the sulfur atom. 相似文献
56.
Kenji Kojima Kusuo Nishiyama Kanetada Nagamine Hironobu Ikeda 《Hyperfine Interactions》1993,78(1-4):429-433
The site diluted finite spin cluster system Rb2CO
x
Mg1–x
F4 (x=0.15, 0.4, 0.5) has been investigated by the +SR technique. Muon spin relaxation was observed in these diluted magnetic systems in a weak longitudinal field of 100 G. By reducing temperature below 100 K, the experimental data show features of slowing down phenomena of the Co electron moments in the finite spin clusters. 相似文献
57.
H. Shiromaru T. Moriwaki H. Ikeda Y. Achiba 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,26(Z1):216-218
A simple threshold electron analyzer was constructed and laser photodetachment threshold electron spectra of Si– and Si
4
–
were measured. 相似文献
58.
Eietsu Hasegawa Shinya Takizawa Akira Yamaguchi Naoki Chiba Hiroshi Ikeda 《Tetrahedron》2006,62(27):6581-6588
Photoinduced electron-transfer reactions of several ketone substrates were studied to evaluate the utilities of 1,6-bis(dimethylamino)pyrene (BDMAP), 1,6-dimethoxypyrene (DMP), 9,10-bis(dimethylamino)anthracene (BDMAA), and 9,10-dimethoxyanthracene (DMA) as electron-donating sensitizers cooperating with 2-aryl-1,3-dimethylbenzimidazolines. BDMAP and DMP generally led higher conversion of ketones and better yield of reduction products compared to BDMAA and DMA. 相似文献
59.
Carbazoledioxazines with an angular type structure (5,15-dialkyl-7,17-dialkyloxy-9,19-dichloro-5,15-dihydrodiindolo[2,3-c:2′,3′-n]triphenodioxazines) were selectively synthesized by electrochemical oxidative ring closure of precursors (2,5-bis(9-alkyl-2-alkyloxy-3-carbazolylamino)-3,6-dichloro-1,4-benzoquinones). The structure was confirmed by 1H-nmr and other instrumental analyses. Their thermal properties and solubilities were investigated and were compared with those of carbazoledioxazines with a linear type structure. 相似文献
60.
M. Ueshima K. Sano M. Ikeda K. Yoshino J. Okamura 《Research on Chemical Intermediates》1998,24(2):133-141
The selective catalytic oxidation (SCO) of ammonia to N2 was studied by using a series of noble metal-V2O5-WO3 catalysts supported on titania-silica (TS) prepared by coprecipitation method. In the V2O5-WO3 catalyst system, the use of TS as a support was very effective to enhance catalytic activity compared with TiO2 or SiO2 alone. The addition of a slight amount of Pd and Ir to V2O5-WO3/TS catalyst caused also remarkable enhancement of the catalytic activity without decreasing the selectivity to N2. The present catalysts provide remarkably high catalytic performance for SCO of ammonia to N2 under the practical reaction conditions for an industrial application. 相似文献