共查询到20条相似文献,搜索用时 12 毫秒
1.
M. Madesclaire V. P. Zaitsev J. V. Zaitseva S. Kh. Sharipova 《Chemistry of Heterocyclic Compounds》2007,43(10):1325-1332
A synthesis is reported for (4R,5R)-and (4S,5S)-4-hydroxymethyl-5-(4-nitrophenyl)oxazolidin-2-ones and (1′R,4R)-and (1′S,4S)-4-[hydroxy(4-nitrophenyl)methyl]oxazolidin-2-ones from (1R,2R)-and (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediols. The effect of the experimental conditions on the formation of these compounds
was studied.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1562–1570, October, 2007. 相似文献
2.
Stereoselectivity of reductive amination of (R)-1-hydroxy-1-phenylpropan-2-one by methylamine was studied. From the four isomers possible, only two are produced by this
reaction. These are marked as (−)-(1R,2S)-ephedrine (desired product) and (+)-(1S,2R)-ephedrine. The reaction stereoselectivity depends both on the type of the catalyst and reaction conditions. The most suitable
type is the supported platinum. However, this catalyst rapidly deactivates. With a decreasing activity of Pt catalyst, the
stereoselectivity decreases. It is also decreased during the production of the second liquid phase (water) in the reaction
mixture. 相似文献
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T. G. Drushlyak L. A. Kutulya N. S. Pivnenko V. V. Vashchenko 《Russian Journal of General Chemistry》2005,75(4):622-627
Carbonylation of (E)-2-(4-halobenzylidene)-p-menthan-3-ones, catalyzed by PdCl2(PPh3)2, gave a distereometric mixure of 4-[(1R,4R)- and (1R,4S)-3-oxo-p-menthan-2-ylidenemethyl]benzoic acids, whose reaction with phenols gave 1R,4R diastereomers of the corresponding esters.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 659–664.Original Russian Text Copyright © 2005 by Drushlyak, Kutulya, Pivnenko, Vashchenko. 相似文献
5.
Summary {\rtf1\ansi\ansicpg1250\deff0\deflang1038\deflangfe1038\deftab708{\fonttbl{\f0\froman\fprq2\fcharset238{\*\fname Times New Roman;}Times New Roman CE;}}
\viewkind4\uc1\pard\f0\fs20 New explanations are given for two types of irregular thermogravimetric (TG) data. A TG relationship between mass and temperature is derived on the basis of migration behavior of bubbles generated in bulk of sample system, and superposed on that derived on the basis of kinetics of the 4\super th\nosupersub order event, which is superposed on the experimental TG data obtained from three reference papers. This suggests that these TG data are reflecting migration of bubbles. A dependence of TG behavior on heating rate, which is contrary to usual that, is shown and is explained in terms of event-rate determination by boiling.
\par } 相似文献
6.
A new compound (5R, 10R)-3,8-dihydroxy-5,10-diethoxy-5,10-dihydrochromeno[5,4,3-cde]chromene monohydrate was obtained from 3,4-dihydroxybenzaldehyde in aerobic basic aqueous ethanol solution in the presence
of manganese chloride and triethylamine and crystallized in orthorhombic P212121 space group (denoted as 1). When 1 was recrystallized from aqueous methanol, it was transformed to another crystal (2) with the same composition but in P21/n space group. The drastic difference in the extensive hydrogen bond network makes 1 a 3D and 2 a 2D infinite supramolecular structure, respectively. 相似文献
7.
A new method is proposed for the synthesis of indole derivatives containing a chiral substituent at the nitrogen atom, which
includes the direct alkylation of indole derivatives with tert-butyl (2S)-(p-tolylsulfonyloxy)propionate, obtained from commercial
ethyl (S)-lactate with subsequent conversion to the corresponding p-toluenesulfonyloxy derivative by hydrolysis, and esterification.
Dedicated to Academician B. A. Trofimov on his 70th birthday.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1391–1398, September, 2008. 相似文献
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Summary Retention characteristics of metoprolol have been studied in reversed phase mode on RP2, RP8 and CN columns. The plots of retention time as a function of the acetonitrile content and of the ionic strength of the mobile phase permitted the choice of the best conditions to separate metoprolol from plasma components by switching of these three types of columns.Human plasma (0.5–1 ml) diluted with water is first injected on a RP2 column (25–40 m particle diameter, prepared by dry packing) and rinsed with water. The sample is then back eluted with acetonitrile-0.022 M acetate buffer (7525, v:v) and switched to a CN column (10 cm long, 5 m particle diameter). The heart cut of the eluate is selected and loaded on a RP8 analytical column (25 cm long, 5 m particle diameter) with acetonitrile-0.088 M acetate buffer (7525, v:v) as mobile phase.Auto-sampler and switching valves are actuated automatically by a computing integrator based on a fixed time schedule. The duration of one cycle is about 30 min, but the last analytical step is about 15 min and represents the time interval between two injections. Metoprolol, its alpha-hydroxy metabolite and the internal standard are detected by fluorescence (ex= 225 nm; em > 320 nm).Presented at the 14th International Symposium on Chromatography London, September, 1982 相似文献
10.
I. N. Shishkina V. M. Dem’yanovich A. A. Kuznetsova K. A. Potekhin N. S. Zefirov 《Doklady Chemistry》2008,423(1):279-282
11.
V. M. Dem’yanovich I. N. Shishkina Ya. A. Gritsyuk K. A. Potekhin A. V. Chesnova L. D. Ashkinadze 《Russian Journal of Organic Chemistry》2005,41(4):556-559
The condensation of lithiated (S)-N,N-dimethyl-1-phenylethylamine with o-methoxybenzophenones occurs in a nonstereoselective fashion due to possible coordination of lithium not only at the carbonyl group but also at the oxygen atom of the ortho-methoxy group.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 567–570.Original Russian Text Copyright © 2005 by Dem’yanovich, Shishkina, Gritsyuk, Potekhin, Chesnova, Ashkinadze. 相似文献
12.
Anita Kovács I. Csóka Magdolna Kónya E. Csányi A. Fehér I. Erős 《Journal of Thermal Analysis and Calorimetry》2005,82(2):491-497
Summary The properties of the inner and the external aqueous phases, were studied in w/o/w multiple emulsions with light microscopic image analysis and differential scanning calorimetry (DSC). The importance of multiple
emulsions lies in the presence of these aqueous phases, making them available for sustained, controlled drug delivery systems.
Differentiation of these two aqueous phases, studying the effect of manufacturing technology on droplet structure, quantitative
determination of phase volumes and any changes occurring during storage are essential when planning w/o/w emulsions. The present study uses microscopic observations combined with DSC measurements in order to identify the formed
structure, at developmental stage in case of different components, preparation methods, and stirring rates. These tools are
beneficial during manufacturing as in process controls, or to ensure product quality. 相似文献
13.
Krisztián Bogár 《Central European Journal of Chemistry》2005,3(1):63-71
(R, R)-(−)-N, N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediaminocobalt(II) was encapsulated into MCM-22 using the zeolite synthesis method. The
encapsulated catalyst proved to be active in the oxidation of α-methylstyrene with NaOCl with higher specific activity than
the homogeneous catalyst. At the same time, this encapsulated catalyst was completely inactive in the hydrolytic kinetic resolution
of racemic styrene oxide. This observation is in a good correlation with the assumption of the cooperative bimetallic mechanism
proposed by Annis and Jacobsen. 相似文献
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In this study, (1R,2R)-1,2-bis-(5-amino-1,3,4-thiadiazol-2-yl)ethane-1,2-diol (2), was synthesized by using (2R,3R)-(+)-Tartaric acid (1) as starting compound. Then the diazo component 3 was obtained from 2 and 1-naphthol. In addition, the structures of the synthesized compounds 2 and 3 were confirmed by elemental analyses, IR, 1H-NMR, and 13C-NMR spectra.
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Published in Kimiya Prirodnikh Soedinenii, No. 5, pp. 465–466, September–October, 2005. 相似文献
17.
Wan-Xing Wei Yuan-Jiang Pan Hong Zhang Cui-Wu lin Teng-You Wei 《Chemistry of Natural Compounds》2004,40(5):460-464
Three compounds were isolated from Phyllanthus niruri Linn. One effective method, improved dry column liquid chromatography for isolating these compounds, was applied on a silica gel column. It is a combination of conventional dry column chromatographic and flash chromatographic techniques. Structures of those obtained compounds were elucidated by means of spectral techniques including IR, MS, and 1D NMR and 2D NMR. Compound 1 was elucidated as 2,3,5,6-tetrahydroxybenzyl acetate. Compound 2 , 2,4,5-trihydroxy-3-(4,6,7-trihydroxy-3-oxo-1,3-dihydroisobenzofuran-5-yl)-benzoic acid methyl ester, was given the name phyllangin, and compound 3 was named corilagin. Compounds 1 and 2 are new compounds.Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 380–382, September–October, 2004. 相似文献
18.
Summary A computer-assisted method is described for optimization of multi-component, mobile phase selection for separating enantiomers of four pesticides in normal-phase HPLC. The method is based on the triangle, solvent-selection concept using a statistical scanning method. The optimization of the separation over the experimental region is based on a special polynomial estimation from seven experimental runs, and resolution (Rs) is used as the selection criterion. Excellent agreement was obtained between predicted and experimental data. 相似文献
19.
A. D. Dubonosov V. P. Rybalkin Ya. Yu. Vorob’eva V. A. Bren’ V. I. Minkin S. M. Aldoshin V. V. Tkachev A. V. Tsukanov 《Russian Chemical Bulletin》2004,53(10):2248-2252
It was shown by electron absorption spectroscopy and X-ray diffraction analysis that steric strains in photochromic 2-(N-acyl-N-arylaminomethylene) benzo[b]thiophen-3(2H)-one molecules ortho-substituted in the N-phenyl ring increase the quantum yield of the N→O photoinduced rearrangement in accord with an increase in the steric constant of the ortho-substituent.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2151–2155, October, 2004. 相似文献