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81.
Total synthesis of spider toxins HO-416b (1) and Agel-489 (2) was accomplished using the 2-nitrobenzenesulfonamide (Ns) group as both a protecting and activating group. In this strategy, the C-N bonds were constructed by alkylation of sulfonamides with alkyl halides or Mitsunobu reaction with the corresponding alcohol. Beginning with monoprotection of the symmetrical diamine, the construction of the backbone from diamine 3 was efficiently accomplished in 7 steps for 14 and 9 steps for 29. Removal of the Ns group while the substrate was attached to a novel solid support enabled the efficient isolation of this highly polar compound. 相似文献
82.
Yokoshima S Tokuyama H Fukuyama T 《Angewandte Chemie (International ed. in English)》2000,39(22):4073-4075
83.
The reaction of 2,3-dichloro-5,6-dicyanopyrazine ( 1 ) with enamines as well as a few tertiary amines as enamine precursors was investigated. Both reactions gave aminovinyl-substituted pyrazine derivatives. During the attempted purification of 3c or 3d by column chromatography on silica gel, 2-chloro-5,6-dicyano-3-(1′-oxocyclopent-2′-yl)pyrazine ( 4 ) was obtained, apparently by hydrolytic cleavage. The products prepared are all of interest as potential pesticides. 相似文献
84.
Minoru Kumakura Masaru Yoshida Isao Kaetsu 《Applied biochemistry and biotechnology》1978,3(3):175-183
The immobilization ofStreptomyces phaeochromogenes cells was studied by the radiation-induced polymerization of various hydrophobic glass-forming monomers at low temperatures. The glucose isomerase activity of cells immobilized in hydrophobic polymers showed no decrease in activity with repeated use (batch enzyme reaction). Activity increased with increasing monomer concentration in contrast to results with the immobilized enzyme. The hydrophobic polymer composite was microspheric in form. The particle diameter of the composite increased with the increasing monomer concentration.K m values of the immobilized cells were close to that of intact cells. It was deduced that the cells were trapped on the surface part of the hydrophobic polymer ready to react with the substrate, and not within the matrix where diffusion would play an important role in reaction rates. 相似文献
85.
Munetaka Nakata Masaaki Sugie Harutoshi Takeo Chi Matsumura Tsutomu Fukuyama Kozo Kuchitsu 《Journal of Molecular Spectroscopy》1981,86(1):241-249
The microwave spectra of four isotopic species of dichlorine monoxide (OCl2) have been observed, and the rotational constants have been obtained. The rm structure for each isotopic species has been determined by Watson's method. The equilibrium structure has been estimated by taking proper averages of rm structures to be and ∠eClOCl = 110.886(6)°. The general applicability and the merit of the present method for estimating the equilibrium structure are pointed out. 相似文献
86.
The C-S stretching vibrations of 28 aliphatic sulfides including one thiol are summarized, and all of the C-S stretching bands are classified into several groups. An extraordinarily low frequency associated with the ethyl group is discussed briefly. 相似文献
87.
H. Fukuyama 《Surface science》1976,58(1):320-324
Orbital magnetic moment and the frequency dependent conductivities of the Wigner crystal are examined in the harmonic approximation. The effects of scattering on the collective modes are also discussed. 相似文献
88.
Munetaka Nakata Tsutomu Fukuyama Kozo Kuchitsu Harutoshi Takeo Chi Matsumura 《Journal of Molecular Spectroscopy》1980,83(1):118-129
The microwave spectra of eight isotopic species of COCl2 have been observed, and the following rotational constants have been obtained: An analysis of the rotational constants has resulted in the rs and rm structures. The equilibrium structure, re, has been estimated by combining the rm parameters derived according to Watson's method and the re bond distances estimated in our recent electron-diffraction and spectroscopic studies to be , , ∠eClCCl = 111.79 ± 0.24°. 相似文献
89.
Calorimetric measurements at 25°C were made to determine the thermodynamic quantities for the intercalation of pyridine with α- and γ-zirconium phosphates. These phosphates showed exothermic reactions with ΔH0 = ?59.3 and ?21.9 kJ mole?1, respectively. The large difference between the depyridination temperatures for both intercalates is rediscussed with the aid of the ΔG0 data obtained. 相似文献
90.
Studer A Amrein S Matsubara H Schiesser CH Doi T Kawamura T Fukuyama T Ryu I 《Chemical communications (Cambridge, England)》2003,(10):1190-1191
4-[(Trimethylstannyl)diphenylsilyl]butanoyl radical, arising from the corresponding 3-(stannylsilyl)propyl radical and CO, undergoes an SHi reaction at Si with extrusion of trimethyltin radical to give silacyclopentanone. The parent 3-(stannylsilyl)propyl radical was also found to isomerize to (3-stannylpropyl)silyl radical via a 1,4-Sn shift from Si to C with a rate constant of 9.3 x 10(4) s-1 at 80 degrees C. Ab initio and DFT MO calculations support a front-side attack mechanism. 相似文献