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231.
232.
Kota Yamaguchi Takeshi Noda Yusuke Higuchi Naoyuki Aoki Rika Yamaguchi Miwa Kubo Kenichi Harada Yoshiyasu Fukuyama Hideaki Hioki 《Tetrahedron letters》2014
An alkoxyamine linker was applied for the solid-phase synthesis of benzazoles, quinazolines, and quinazolinones. Aromatic aldehydes were anchored by aldoxime linkage. After some reactions on a solid support, the products were cleaved with paraformaldehyde under the acidic conditions to afford the corresponding aldehydes, which were subsequently subjected to oxidative coupling with 2-substituted anilines under air atmosphere to give the desired compounds. 相似文献
233.
234.
Ohne Zusammenfassung 相似文献
235.
Naoyuki Koide Kazuyoshi Iimura Masatami Takeda 《Journal of polymer science. Part A, Polymer chemistry》1973,11(12):3161-3169
Studies have been made by NMR and ESR spectroscopy to elucidate the reaction mechanism in which the Ti(NEt2)4–AlMe3 catalyst system is involved. The two reaction products of Ti(NEt2)3Me and Al(NEt2)Me2 have been confirmed by NMR spectroscopy when Ti(NEt2)4 is reacted with AlMe3, and two kinds of paramagnetic species have been noted by ESR spectroscopy. It has been found that Ti(NEt2)3Me plays an important role as an active species for the polymerization of styrene. 相似文献
236.
237.
A connected graph G is called t-tough if t · w(G - S) ? |S| for any subset S of V(G) with w(G - S) > 1, where w(G - S) is the number of connected components of G - S. We prove that every k-tough graph has a k-factor if k|G| is even and |G| ? k + 1. This result, first conjectured by Chvátal, is sharp in the following sense: For any positive integer k and for any positive real number ε, there exists a (k - ε)-tough graph G with k|G| even and |G| ? k + 1 which has no k-factor. 相似文献
238.
Furostifoline, a furo[3,2-a]carbazole alkaloid, was synthesized in 10% overall yield in four steps from 2-acetyl-3-bromofuran. The key step of this synthesis was the 2-substituted indole formation with tetrabutylammonium fluoride (TBAF) from 2-(2-propenyl)-3-((2-ethoxycarbonylamino)phenylethynyl)furan, which was easily prepared from ethyl 2-ethynylphenylcarbamate with 3-bromo-2-(2-propenyl)furan by the Sonogashira reaction. 相似文献
239.
Iwatsuki S Mizushima C Morimoto N Muranaka S Ishihara K Matsumoto K 《Inorganic chemistry》2005,44(22):8097-8104
Detailed equilibrium and kinetic studies on axial water ligand substitution reactions of the "lantern-type" platinum(III) binuclear complex, [Pt(2)(mu-HPO(4))(4)(H(2)O)(2)](2)(-), with halide and pseudo-halide ions (X(-) = Cl(-), Br(-), and SCN(-)) were carried out in acidic aqueous solution at 25 degrees C with I = 1.0 M. The diaqua Pt(III) dimer complex is in acid dissociation equilibrium in aqueous solution with -log K(h1) = 2.69 +/- 0.04. The consecutive formation constants of the aquahalo complex () and the dihalo complex () were determined spectrophotometrically to be log = 2.36 +/- 0.01 and log = 1.47 +/- 0.01 for the reaction with Cl(-) and log = 2.90 +/- 0.04 and log = 2.28 +/- 0.01 for the reaction with Br(-), respectively. In the kinetic measurements carried out under the pseudo-first-order conditions with a large excess concentration of halide ion compared to that of Pt(III) dimer (C(X)()- > C(Pt)), all of the reactions proceeded via a one-step first-order reaction, which is a contrast to the consecutive two-step reaction for the amidato-bridged platinum(III) binuclear complexes. The conditional first-order rate constant (k(obs)) depended on C(X)()- as well as the acidity of the solution. From kinetic analyses, the rate-limiting step was determined to be the first substitution process that forms the monohalo species, which is in rapid equilibrium with the dihalo complex. The reaction with 4-penten-1-ol was also kinetically investigated to examine the reactivity of the lantern complex with olefin compounds. 相似文献
240.
H. Nakahara Y. Oura K. Sueki M. Ebihara W. Sato Sk. A. Latif T. Tomizawa S. Enomoto C. Yonezawa Y. Ito 《Journal of Radioanalytical and Nuclear Chemistry》2000,244(2):405-411
An internal monostandard method for PGAA is proposed for completely non-destructive analysis of elements in bulky samples by the use of a neutron beam guided out from the reactor. The method is essentially the same as the k
0 method except that it corrects for the change of relative -ray counting efficiencies caused by the absorption and scattering of neutrons and absorption of -rays within the sample. Some examples of applications to archaeological samples of earthen wares, bronze mirrors, and to voluminous meteorite samples are demonstrated, and its future application to the in-situ studies of distribution and metabolism of a certain elements in animals is also explained. 相似文献