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31.
Kotera M Roupioz Y Defrancq E Bourdat AG Garcia J Coulombeau C Lhomme J 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(22):4163-4169
On the basis of molecular modeling studies, the 7-nitroindole nucleoside 1 was selected as a suitable photochemical precursor for photochemical generation of the C1' deoxyribosyl radical under irradiation, which led to 2'-deoxyribonolactone. The nitro-indole nucleoside derivatives 1a and 1b were prepared and their conformation was determined by X-ray crystallography and NMR spectroscopy. The photoreaction of these nucleosides gave the corresponding deoxyribonolactone derivatives efficiently, with release of 7-nitrosoindole. This reaction was successfully applied to synthesis of oligonucleotides containing the deoxyribonolactone lesion. 相似文献
32.
E. I. Klimova E. A. Vazquez Lopez T. Klimova M. Martinez Garcia N. N. Meleshonkova L. Ruiz Ramirez 《Russian Journal of General Chemistry》2004,74(12):1830-1835
Monocyclic 3- and 5-ferrocenyl-4,5-dihydropyrazoles with a free NH group in the molecule react with acetylacetone to form the corresponding enaminocarbonyl compounds. The latter were isolated as a single isomer, presumably E. 3-Ferrocenyldihydropyrazoles and 5-ferrocenyl-3-(p-methoxyphenyl)-4,5-dihydropyrazole analogously react with acetoacetic ester. 5-Ferrocenyl-3-phenyl-, 3-(p-bromophenyl)-5-ferrocenyl, and 3,5-diferrocenyl-4,5-dihydropyrazoles react with acetoacetic ester to form acetoacetylpyrazolides.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 12, 2004, pp. 1942–1947.Original Russian Text Copyright © 2004 by E. Klimova, Vazquez Lopez, T. Klimova, Martinez Garcia, Meleshonkova, Ruiz Ramirez.This revised version was published online in April 2005 with a corrected cover date. 相似文献
33.
Acetylcholinesterase (AChE) (EC 3.1.1.7) was modified with activated monomethoxypolyethylene glycol (mPEG). A decrease of 50% in the catalytic activity was measured during the coupling reaction and the change in the surface properties of AChE was used to separate by hydrophobic interaction chromatography the native and the modified enzyme. The native and the modified enzymes were found to have the same optimalcatalytic conditions. Moreover, the Michaelis constant of both enzymes were similar, whereas theV m and the bimolecular-velocity constant calculated for organophosphorus inhibitors were slightly higher for the modified AChE. Finally, the modification with mPEG did not improve the thermal stability, whereas the stability in a few organic solvents increased. 相似文献
34.
35.
The preparation of 2-amino-5-nitrothiophene, 2-formamido-5-nitrothiophene, 2-acetamido-5-nitrothiophene and 2-t-butyloxycarbonylamino-5-nitrothiophene are described. Abnormal values of the coupling constants J3.4 had been observed in the 1H-nmr spectra of compounds obtained. 相似文献
36.
Kumar K Michalik D Garcia Castro I Tillack A Zapf A Arlt M Heinrich T Böttcher H Beller M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(3):746-757
A practical route for the synthesis of new biologically active 5-HT(2 A) receptor antagonists has been developed. In only three catalytic steps, this class of central nervous system (CNS) active compounds can be synthesized efficiently with high diversity. As the initial step, an anti-Markovnikov addition of amines to styrenes provides an easy route to N-(arylalkyl)piperazines, which constitute the core structure of the active molecules. Here, base-catalyzed hydroamination reactions of styrenes with benzylated piperazine proceeded in high yield even at room temperature. After catalytic debenzylation, the free amines were successfully carbonylated with different aromatic and heteroaromatic halides and carbon monoxide to yield the desired compounds in good to excellent yields. The two key reactions, base-catalyzed hydroamination of styrenes and palladium-catalyzed aminocarbonylation of haloarenes/heterocycles, showed tolerance towards various functional groups, thereby demonstrating the potential to synthesize a wide variety of new derivatives of this promising class of pharmaceuticals. 相似文献
37.
38.
A new kinetic method for determination of selenium is based on its inhibitory effect on the Pd(II)-catalysed reaction between Pyronine G and hypophosphite. Under the optimum experimental conditions (6 x 10(-5)M Pyronine G, 0.4M hypophosphite, 0.4 mug/ml Pd(II), pH 2.8, temperature 22.0 +/- 0.2 degrees ), Se can be determined in the concentration range 0.033-0.50 mug/ml. The method suffers from numerous interferences and is thus limited in application. It has been applied to the determination of selenium in spring waters and pharmaceutical preparations. 相似文献
39.
P. Staszczuk J. C. Bazan M. Błachnio D. Sternik N. J. Garcia 《Journal of Thermal Analysis and Calorimetry》2006,86(1):57-68
This paper presents possible applications of thermal analysis, sorptometry
and porosimetry to study physico-chemical properties of Na- and La-montmorillonite
samples, especially for determination of total surface heterogeneity. The
quasi-isothermal thermogravimetric (Q-TG) mass loss and its first derivative
(Q-DTG) curves with respect to temperature and time obtained during programmed
liquid thermodesorption under quasi-isothermal conditions have been used to
study adsorbed layers and heterogeneous properties of the Na- and La-montmorillonites.
Calculations of the desorption energy distribution functions by analytical
procedure using mass loss Q-TG and differential mass loss Q-DTG curves of
thermodesorption under quasi-isothermal conditions of polar and non-polar
liquid vapours preadsorbed on a material surface are presented. Parameters
relating to porosity of samples were determined by sorptometry, mercury porosimetry
and atomic force microscopy (AFM). From nitrogen sorption isotherms from sorptometry
and porosimetry methods, the fractal dimensions of montmorillonites have been
calculated. Moreover, a new approach is proposed to calculate fractal dimensions
of materials obtained from Q-TG curve; this is compared with values obtained
by the above methods. The total heterogeneous properties (energy distribution
function and pore-size distribution functions) of samples studied were estimated.
The radius and pore volume of the tested samples calculated on the basis of
thermogravimetry, sorptometry and porosimetry techniques were compared and
good correlations obtained. 相似文献
40.
M. Benassi R. D. M. Garcia C. E. Siewert 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1984,35(3):308-320
Several representations of the dispersion matrix (z) basic to analytical solutions for a theory of radiative transfer that includes the effects of polarization are reported, and a method for computing the zeros of det (z) is discussed. Numerical results are given for several specific models.
Zusammenfassung Verschiedene Darstellungen der Dispersionsmatrix (z), welche grundlegende Bedeutung für die analytischen Lösungen der Theorie der Strahlungsübertragung mit Polarisation hat, werden angegeben. Eine Methode zur Berechnung der Nullstellen von det (z) wird diskutiert. Es werden numerische Ergebnisse für verschiedene Modelle angegeben.相似文献