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51.
An efficient approach for achieving radical cyclizations by using hydroxamate ester as a coordination tether with Lewis acid was studied. The chiral Lewis acid-mediated cascade radical addition-cyclization-trapping reaction proceeded smoothly with good enantio- and diastereoselectivities, providing various chiral γ-lactams. 相似文献
52.
The synthesis and spectroscopic characterization of the title complexes correspond to isoelectronic system of o-quinodi-methane complex are described. 相似文献
53.
Yoichi Asada Keith Slevin Tomi Ohtsuki 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):228
Electron transport phenomena in disordered electron systems with spin–orbit coupling in two dimensions and below are studied numerically. The scaling hypothesis is checked by analyzing the scaling of the quasi-1D localization length. A logarithmic increase of the mean conductance is also confirmed. These support the theoretical prediction that the two-dimensional metal in systems with spin–orbit coupling has a perfect conductivity. Transport through a Sierpinski carpet is also reported. 相似文献
54.
In Raman-Nath diffraction by water, the intensities of even order light beams are selectively enhanced by suspension of microparticles.
The diffracted beams remain for several seconds even after the ultrasonic oscillation stops. These phenomena are elucidated
by assuming the laminar arrangement of micropaticles due to the ultrasonic wave. 相似文献
55.
Jing Chen Masahiro Ueda Katsuhiko Asada Keiji Taniguchi 《Optics and Lasers in Engineering》1998,29(1):221
An optical method to measure the weight density of raw glass wool has been developed for use in a manufacturing plant. The method is based on the light attenuation theory. The system consists of the usual white light as a light source, a solar cell as a light-sensitive receiver, an amplifier, a personal computer with an A/D converter for data acquisition and a monitor for display of the data. The accuracy of the system was found to be above 98% and the system can be effectively applied to practical use in the factory. The system may be further applied for quality control in manufacturing raw glass wool. 相似文献
56.
Atsushi Yamamoto Mio Kawai Mitsunori Sakamoto Shuji Kodama Kazuichi Hayakawa 《Analytical sciences》2008,24(3):361-364
A sensitive and variable-wavelength optical rotatory (OR) detector for high-performance liquid chromatography is presented. This design is entirely different from that of conventional OR detectors consisting of a crossed polarizer pair. By placing a polarizing prism and a retardation plate into a commercial circular dichroism (CD) detector, the OR signal was obtained. The Mueller matrix approach was used to prove the principle of the OR signal appearance. Sugars and 4-androstene-3,17-dione were chosen as test compounds. The limit of detection was below 0.5 microg of injected sucrose at 260 nm, which was superior to that obtained with a conventional OR detector. For 4-androstene-3,17-dione, which is CD active, and shows a large anomalous OR dispersion curve, our detector gave a large OR signal with approximately half the intensity of the CD signal at 340 nm. 相似文献
57.
An inductively coupled plasma is extracted into a quartz vacuum chamber through an orifice to observe optical characteristics of the extracted afterglow. The Mach disk, the barrel shock and the zone of silence, which are familiar in supersonic molecular beam experiments with neutral gases, are clearly observed. Axial profiles of the emission of various lines are measured with a photodiode array spectrometer. Intensities of ionic lines as well as atomic lines are stronger at the Mach disk than in the zone of silence. The location of the Mach disk with varying chamber presure is in conformity with an experimental equation obtained in supersonic molecular beam experiments. 相似文献
58.
Hiroyoshi Kamogawa Yuichiro Haramoto Yukihiro Misaka Yasuhiro Asada Yumiko Ohno Masato Nanasawa 《Journal of polymer science. Part A, Polymer chemistry》1985,23(5):1517-1526
p-Styrenesulfonate esters of primary and secondary perfume alcohols and phenols, including citronellol, 1-menthol, borneol, β-phenethyl alcohol, eugenol, p-anisyl alcohol, cinnamyl alcohol, and geraniol, and herbicide alcohols such as 2,4-dichloro- and 2,4,5-trichlorophenoxy-ethanols were synthesized using p-styrenesulfonyl chloride in the presence of bases such as pyridine, triethylamine, sodium hydrogen carbonate, and sodium hydride. The hydrolytic behavior of sulfonate ester monomers and their copolymers with N-vinyl-2-pyrrolidone to liberate perfume and herbicide alcohols was structure-dependent, thereby affording chemical release control. 相似文献
59.
Yamaguchi K Koike T Kotani M Matsushita M Shinachi S Mizuno N 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(22):6574-6582
Three kinds of hydrogen-transfer reactions, namely racemization of chiral secondary alcohols, reduction of carbonyl compounds to alcohols using 2-propanol as a hydrogen donor, and isomerization of allylic alcohols to saturated ketones, are efficiently promoted by the easily prepared and inexpensive supported ruthenium catalyst Ru(OH)x/Al2O3. A wide variety of substrates, such as aromatic, aliphatic, and heterocyclic alcohols or carbonyl compounds, can be converted into the desired products, under anaerobic conditions, in moderate to excellent yields and without the need for additives such as bases. A larger scale, solvent-free reaction is also demonstrated: the isomerization of 1-octen-3-ol with a substrate/catalyst ratio of 20,000/1 shows a very high turnover frequency (TOF) of 18,400 h(-1), with a turnover number (TON) that reaches 17,200. The catalysis for these reactions is intrinsically heterogeneous in nature, and the Ru(OH)x/Al2O3 recovered after the reactions can be reused without appreciable loss of catalytic performance. The reaction mechanism of the present Ru(OH)x/Al2O3-catalyzed hydrogen-transfer reactions were examined with monodeuterated substrates. After the racemization of (S)-1-deuterio-1-phenylethanol in the presence of acetophenone was complete, the deuterium content at the alpha-position of the corresponding racemic alcohol was 91%, whereas no deuterium was incorporated into the alpha-position during the racemization of (S)-1-phenylethanol-OD. These results show that direct carbon-to-carbon hydrogen transfer occurs via a metal monohydride for the racemization of chiral secondary alcohols and reduction of carbonyl compounds to alcohols. For the isomerization, the alpha-deuterium of 3-deuterio-1-octen-3-ol was selectively relocated at the beta-position of the corresponding ketones (99% D at the beta-position), suggesting the involvement of a 1,4-addition of ruthenium monohydride species to the alpha,beta-unsaturated ketone intermediate. The ruthenium monohydride species and the alpha,beta-unsaturated ketone would be formed through alcoholate formation/beta-elimination. Kinetic studies and kinetic isotope effects show that the Ru-H bond cleavage (hydride transfer) is included in the rate-determining step. 相似文献
60.
Kiyomi Kakiuchi Takuo Nakao Mitsunori Takeda Yoshito Tobe Yoshinobu Odaira 《Tetrahedron letters》1984,25(5):557-560
The novel synthesis of descarboxyquadrone (3) and its model compound (4) by using the acid-catalyzed rearrangement of [4.3.2]propellanones is described. 相似文献