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121.
Takushi Nagata Kiyoaki D. Sugi Kiyotaka Yorozu Tohru Yamada Teruaki Mukaiyama 《Catalysis Surveys from Japan》1998,2(1):47-57
Optically active aldiminato cobalt(II) complexes have been found to catalyze the enantioselective reduction of ketones with sodium borohydride affording the corresponding optically active secondary alcohols in high chemical yields with high enantioselectivities. The enantioselective borohydride reduction is also applicable to not only C=O bonds in aromatic ketones but also to C=N bonds in aromatic imines. 相似文献
122.
Junji Furukawa Eiichi Kobayashi Shiro Nagata T
hei Moritani 《Journal of polymer science. Part A, Polymer chemistry》1974,12(8):1799-1807
13C NMR spectra of acrylic monomers complexed with a Lewis acid were measured and their electronic structures discussed in relation to their alternating copolymerizability. The β-carbon of acrylonitrile and methacrylonitrile showed a downfield shift due to the complex formation with the Lewis acid, while the α-carbon showed an upfield shift and the nitrile carbon showed no significant shift. The degree of shift of olefinic carbons decreased in the following order: AlCl3 > EtAlCl2 > Et1.5AlCl1.5 > Et2AlCl > SnCl4, EtOAlCl2 > Et(EtO)AlCl, which seems to run parallel to the Lewis acidity and acid strength. On the other hand, the chemical shift of olefinic carbons of methyl acrylate, methyl methacrylate, and olefinic diesters was influenced little by complex formation with Lewis acids, whereas the carbonyl and alkoxyl carbons were deshielded significantly by the complex formation. These results are discussed in terms of electron distribution on the carbons and an alternating polymerization mechanism. 相似文献
123.
Sato M Nagata T Tanemura A Fujihara T Kumakura S Unoura K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(9):2166-2178
Ruthenocene-terminated butadienes and hexatrienes were prepared by the Wittig reaction of 3-ruthenocenyl-2-propenals with ruthenocenylmethylphosphonium salts and the Mukaiyama coupling of the propenals, respectively. Cyclic voltammetry of these complexes indicated that they were involved in a stable two-electron redox process. The oxidation potentials for ruthenocene-terminated oligoenes shifted progressively to lower potential with the increasing CH==CH units as follows: Rc--Rc (0.32 V)>RcCH==CHRc (+0.09 V)>Rc(CH==CH)(2)Rc (-0.06 V)>Rc(CH==CH)(3)Rc (-0.07 V), (Rc=ruthenocene). The tendency is in remarkable contrast to that in the successive one-electron redox process. These complexes were chemically oxidized to give stable crystalline solids, whose structures were confirmed by NMR spectroscopy and X-ray analysis to be oligoene analogues of a bis(fulvene) complex, for example, [(eta(5)-C(5)Me(5))Ru[mu(2)-eta(6):eta(6)-C(5)H(4)CH(CH==CH)(n)CHC(5)H(4)]Ru(eta(5)-C(5)Me(5))](2+) (n=1 or 2). The DFT calculation of the two-electron-oxidized species reproduced well the fulvene-complex structure for the ruthenocene moieties. Since both the neutral and oxidized species are stable and chemically reversible, this redox system may be serviceable as a two-electron version of the ferrocene one-electron redox system. 相似文献
124.
Yasushi Nagata 《Annals of the Institute of Statistical Mathematics》1983,35(1):193-199
Summary LetX be a random variable from the one-parameter exponential family with the probability element β(θ) exp (θx)dm(x) for which an ambiguous prior information is available to the effect that θ is likely to be larger than or equal to a known
constant. The information is represented by a fuzzy set with the membership function χ(θ). Then it is shown that
is an admissible estimator for E
0
(X) under the quadratic loss function. 相似文献
125.
In this paper, we describe a method for size-based electrophoretic separation of sodium dodecyl sulfate (SDS)-protein complexes on a polymethyl methacrylate (PMMA) microchip, using a separation buffer solution containing SDS and linear polyacrylamide as a sieving matrix. We developed optimum conditions under which protein separations can be performed, using polyethylene glycol (PEG)-coated polymer microchips and electrokinetic sample injection. We studied the performance of protein separations on the PEG-coated PMMA microchip. The electrophoretic separation of proteins (21.5-116.0 kDa) was completed with separation lengths of 3 mm, achieved within 8 s on the PEG-coated microchip. This high-speed method may be applied to protein separations over a large range of molecular weight, making the PEG-coated microchip approach applicable to high-speed proteome analysis systems. 相似文献
126.
The simultaneous determination of organic dye mixtures by using spectrophotometric methods is a difficult problem in analytical chemistry, due to spectral interferences. By using multivariate calibration methods such as partial least-squares regression (PLSR), it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration stage. In this study, the calibration model is based on absorption spectra in the 350-650-nm range for a set of 16 different mixtures of reactive red 195, reactive yellow 145 and reactive orange 122 dyes, and made the determination of the dye concentrations possible in a validation set with significantly greater accuracy than the conventional univariate calibration method. By using the developed model it was possible to monitor the decolorization kinetic of one dye (reactive orange 122), when the mixture of the three dyes was previously submitted to an ozonation process. 相似文献
127.
Isamu Nagata 《Thermochimica Acta》1982,56(1):43-57
The two-parameter UNIQUAC equation is modified to give better results of vapor—liquid and liquid—liquid equilibria for a variety of binary systems. The proposed equation is easily extended to a multicomponent system without including any ternary (or multicomponent) parameters. The good capability of the equation in data reduction is shown by many illustrative examples for various kinds of strongly nonideal binary and ternary mixtures. 相似文献
128.
A series of novel pentadentate terpyridine-catechol linked ligands were prepared, in which the terpyridine and catechol moieties were linked together by (CH2)n chains of different lengths (n = 4-6). Together with 1-methylimidazole, these ligands formed low-spin, six-coordinate Co(III) complexes. Two of the complexes (n = 4, 5) were characterized by X-ray crystallography [n = 4, monoclinic, P2(1)/c, a = 14.957(7) A, b = 10.585(9) A, c = 23.033(7) A, beta = 106.01(3) degrees, V = 3505(3) A3, Z = 4, R = 0.063; n = 5, monoclinic, P2(1)/c, a = 8.848(7) A, b = 15.78(1) A, c = 25.455(7) A, beta = 93.90(5) degrees, V = 3544(3) A3, Z = 4, R = 0.056], which revealed similar structures around the Co(III) centers but different conformations for the (CH2)n linkers. The (CH2)4 linker showed a straight, symmetric conformation whereas the (CH2)5 linker showed a curved conformation that allowed the accommodation of one extra CH2 unit, suggesting that the (CH2)4 linker presents the "best-fit" length for these complexes. 相似文献
129.
Kawaguchi T Ichikawa T Hasegawa T Saneyoshi M Wakayama T Kato H Yukita A Nagata T 《Chemical & pharmaceutical bulletin》2000,48(4):454-457
Sixteen derivatives of 1-(beta-D-arabinofuranosyl)-2-thiocytosine (araSC), including five 5'-esters, three 3'-esters, five N4-amides and three 5'-phosphodiesters, were synthesized and their reactivity to mouse tissue homogenates, including plasma, liver and intestine, and antitumor activity in mice bearing P388 cells were measured. The ester derivatives had a potent effect on the enzyme systems while the amide and phosphodiester derivatives were less active. The reactivity of ester derivatives was highly dependent on their chemical structure. The reactivity of amides and phosphodiester derivatives on mouse plasma and intestinal homogenate was also dependent on the chemical structure, although their action on intestinal enzymes was very similar. Two of eight ester derivatives showed considerable antitumor activity in vivo, although they also showed serious toxicity indicated by a weight loss in the mice. Four out of five amides and two out of three phosphodiesters showed antitumor activity, and two were highly effective (>200% in T/C, the ratio of the mean survival time of the treated group to that of the control group) with only a very slight weight loss. 相似文献
130.
Optically active 7-exo-substituted-3-p-tosyl-6,8-dioxabicyclo[3.2.1]-octanes prepared from (+)-(R,R)-diethyl tartrate in four or five steps sequence effectively utilizing the inherent C2 symmetry of tartrate, underwent acetolysis to lead to the new type of functionalized and optically active 3,4-dihydro-2Hpyrans in high yields. An application to the unambiguous synthesis of (-)-(6S,1′S)-pestalotin is reported. 相似文献