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1.
Various approaches to the synthesis of per-O-acetylated thioglycosides of N-acetylneuraminic acid (Neu5Ac) containing an unprotected carboxy group starting from the corresponding methyl esters were comparatively studied. One-step demethylation of methyl thioglycoside (LiI, Py, reflux) proceeded inefficiently in contrast to the analogous smooth reaction of phenyl thioglycoside. An indirect route to derivatives with a free carboxy group involving saponification followed by acetylation of hydroxy groups proved to be more efficient for methyl -thioglycoside of Neu5Ac. 相似文献
2.
2,4-Dimethoxybenzyl ester of per-O-acetylated N-acetylneuraminic acid thioglycoside was synthesized and attempts at the oxidative (DDQ-induced) addition of O-nucleophiles (water and galactose derivatives with unprotected hydroxy group at C(6)) to the benzylic carbon atom of this ester were made. 相似文献
3.
Readily accessible N-acetylneuraminic acid (Neu5Ac) glycosyl chloride, which was regarded to be a poor glycosyl donor, was shown to react with dibenzyl phosphoric acid salts in the absence of glycosylation promoters to give the corresponding -Neu5Ac dibenzyl glycosyl phosphate in high yield. 相似文献
4.
Treatment of acetylated phenyl thioglycoside of N-acetylneuraminic acid with m-chloroperbenzoic acid (MCPBA) in CH2Cl2 affords quantitatively mixtures of the respective sulfone and glycal free from the sulfoxide. The outcome of the reaction does not depend on the anomeric configuration of the starting thioglycoside. The sulfone can be selectively prepared (yield 100%) by oxidation with an excess of MCPBA and NaHCO3. In the presence of pyridine (2 equiv.) and MCPBA (2 equiv.), the major product is glycal (yields 81—88%). This version of the reaction can be regarded as a new method for the preparation of sialic acid glycals. 相似文献
5.
V. A. Tartakovsky A. S. Ermakov Yu. A. Strelenko D. B. Vinogradov S. A. Serkov 《Russian Chemical Bulletin》2001,50(5):911-913
A method was developed for the preparation of functionally substituted N-nitrooxazolidines and N-nitrotetrahydro-1,3-oxazines by nitration of the products obtained in the reactions of N-(2-hydroxyalkyl)- and N-(3-hydroxyalkyl)sulfamates with formaldehyde. 相似文献
6.
Yu. Melnik M. Vorona G. Veinberg J. Popelis L. Ignatovich E. Lukevics 《Chemistry of Heterocyclic Compounds》2005,41(6):718-721
2-(1-Alkoxyimino-2,2,2-trifluoroethyl)-5-trimethylsilylfurans were synthesized by the condensation of 2-(trifluoroacetyl)-5-trimethylsilylfuran
with alkoxyamines. According to 1H and 19F NMR spectroscopic data, the alkoxyimino group in the E-isomers descreens the H-3 and H-4 protons of the furan ring more strongly than in the Z-isomers, shifting their signals downfield. The fluorine atoms of the α-trifluoromethyl group in the Z-isomer are characterized by a downfield shift in relation to the E-isomer.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 834–838, June, 2005. 相似文献
7.
Yu. N. Belokon' K. A. Kochetkov M. A. Moskalenko N. I. Raevsky T. F. Savel'eva V. I. Tararov T. D. Churkina 《Russian Chemical Bulletin》1995,44(3):517-519
The radical addition of PriOH andn-butanal to (5R)-5-(l-menthyloxy)furan-2(5H)-one occurs regio- and diastereospecifically at position 4 of the furanone ring.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 345–536, March, 1995.This work was carried out with the financial support of the Russian Foundation for Basic Research (Project No. 93-03-04497). 相似文献
8.
M. Madesclaire P. Coudert V. Gaumet V. P. Zaitsev Yu. V. Zaitseva 《Chemistry of Heterocyclic Compounds》2006,42(5):665-670
We have synthesized a series of (1R,2R,4S,5S,8S)-2,8-diaryl-4-(4-nitrophenyl)-1-aza-3,7-dioxabicyclo[3.3.0]octanes as a result
of reaction of (1S,2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol with aromatic aldehydes. The structure of the compounds obtained
was established on the basis of 1H NMR data.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 757–763, May, 2006. 相似文献
9.
Reactions of N-tosylimidoyl chlorides with the Schiff bases of the general formula TsNH(CH2)nN=CHR (n = 2 or 3; R = Pri, 4-MeOC6H4, 4-Me2NC6H4, and 3-O2NC6H4) afforded 2-substituted 1-tosyl-3-(1-tosyliminoalkyl)imidazolidines (n = 2) or-hexahydropyrimidines (n = 3).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 872–875, May, 2006. 相似文献
10.
S. V. Metlitskikh A. M. Koroteev M. P. Koroteev A. S. Shashkov A. A. Korlyukov M. Yu. Antipin A. I. Stash E. E. Nifantiev 《Russian Chemical Bulletin》2005,54(12):2890-2898
The condensation of D-mannose and D-galactose with aliphatic and aromatic diamines afforded a series of bis(glycosylamino)alkanes and-arenes. A possible mechanism
was proposed for the formation of 1,2-bis(β-D-glycosylamino)benzenes.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2793–2801, December, 2005. 相似文献
11.
Condensation of Schiff"s bases (prepared from 2-hydroxy- or 2-hydroxy-5-methylacetophenones and primary amines) with ethyl polyfluoroalkanoates in the presence of LiH in THF affords 3-alkylamino-3-(2-hydroxyaryl)-1-polyfluoroalkylprop-2-en-1-ones, which undergo cyclization in acidic media into 2-polyfluoroalkyl-4H-chromen-4-iminium salts. When neutralized with aqueous ammonia, the latter give 2-polyfluoroalkyl-4H-chromen-4-imines in high yields. 相似文献
12.
A. A. Korlyukov N. V. Alekseev K. V. Pavlov O. V. Krivolapova V. G. Lakhtin E. A. Chernyshev M. Yu. Antipin 《Russian Chemical Bulletin》2005,54(7):1623-1626
The reaction of adamantane-1-carboxylic acid chloride with trichlorogermylmethanol afforded (trichlorogermyl)methyl adamantane-1-carboxylate,
whose molecular structure was established by 1H NMR spectroscopy and X-ray diffraction analysis.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1576–1579, July, 2005. 相似文献
13.
A. A. Dudinov S. A. Woznesensky M. I. Struchkova L. I. Belen'kii M. M. Krayushkin 《Russian Chemical Bulletin》2000,49(5):954-955
Heating 1-aryl-5,5-dichloropenta-2,4-dien-1-ones with 4-bromophenacylpyridinium bromide in AcOH in the presence of AcONH4 gave 2-aryl-6-(4-bromophenyl)-4-(2,2-dichlorovinyl)pyridines. The reaction products were structurally characterized by1H and13C NMR spectroscopy.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 955–957, May, 2000. 相似文献
14.
1-(N-alkylnitraminomethyl)-3-nitroureas were prepared by nitration of condensation products of urea with formaldehyde andN-alkylsulfamate.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2041–2042, November, 1994. 相似文献
15.
Shin-ichiro Shoda Yoshinori Misawa Yousuke Nishijima Yukiko Tawata Tomohiko Kotake Masato Noguchi Atsushi Kobayashi Takeshi Watanabe 《Cellulose (London, England)》2006,13(4):477-484
Chitinase-catalyzed hydrolytic and transglycosylating behavior of 1,2-oxazoline derivative of N-acetyllactosamine (LacNAc-oxa) 1 has been investigated. An extremely rapid hydrolysis (ring-opening of the oxazoline moiety) could be observed, suggesting that 1 behaves as a transition state analogue substrate for chitinase A1 (Bacillus circulans WL-12). This disaccharide monomer 1 was found to polymerize under basic conditions, giving rise to novel oligosaccharides having a β(1-4)–β(1-6) repeating unit in the main chain. The degree of polymerization of the resulting oligosaccharides was up to 5. This is the first example of enzymatic glycosylation reaction forming a β(1-6) bond catalyzed by chitinase. 相似文献
16.
Zenonas Kuodis Albertas Rutavičius Algirdas Matijoška Olegas Eicher-Lorka 《Central European Journal of Chemistry》2007,5(4):996-1006
New hydrazones of 2-(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-ylthio)acetohydrazide have been obtained and the percentages
of anti/syn - conformers were determined. Based on the analyses of 1H NMR spectra, it was concluded that for hydrazones obtained from the 2- hydroxybenzaldehydes and 2’-hydroxycetophenones the
ratio between the anti-and syn-conformers depends on the strength of intramolecular hydrogen bond (IMHB) between the nitrogen atom of the imino group and
the proton of the 2-hydroxy group. It was shown that increase in IMHB strength results in stabilization of the anti-conformer in solution.
相似文献
17.
B. S. Fedorov N. I. Golovina V. V. Arakcheeva M. A. Fadeev G. V. Strukov V. V. Kedrov G. V. Shilov L. O. Atovmyan 《Russian Chemical Bulletin》1999,48(8):1584-1586
The reaction ofN,N′-bis(2-nitroxyethyl)pyridine-2,6-dicarboxamide with PdCl2 afforded previously unknowncis-(N-2-nitroxyethylpicolinamide-N,N′)dichloropalladium(II) andcis-[2-(2-pyridyl)-2-oxazoline-N,N′]dichloropalladium(II), which were isolated as a cocrystallizate of the molecular compounds. Its structure was established
by X-ray diffraction analysis.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1604–1606, August, 1999. 相似文献
18.
A. I. Krivoshey N. S. Pivnenko S. V. Shishkina A. V. Turov L. A. Kutulya O. V. Shishkin 《Russian Chemical Bulletin》2006,55(6):999-1009
The spatial structure of (Z)-(5R)-methyl-2-(4-phenylbenzylidene)cyclohexanone prepared by photochemical isomerization of the E-isomer was studied by analyzing the magnitudes and temperature dependence of the proton spin-spin coupling constants obtained
by 1H NMR spectroscopy and the results of molecular modeling using semiempirical quantum chemical AM1 and PM3 methods and the
density functional theory (DFT). Comparison of the results obtained for the Z-and E-isomers shows that in both cases the conformational equilibrium for both isomers is characterized by significant preference
of the chair conformer having an equatorial methyl group, namely, − ΔH (chair a ⇌ chair e) = 1.98–2.12 and 1.36–1.54 kcal mole−1 for the Z-and E-isomers, respectively. Distinctions in the non-planarity of the enone fragment and cyclohexanone ring in the Z-and E-isomers under study following from the results of mathematical modeling were confirmed by the experimental values of the
geminal spin-spin coupling constants of protons of the methylene groups in α,α ′-positions with respect to the enone group.
Quantum chemical calculations of the Z-isomer revealed the existence of intramolecular hydrogen bond between the carbonyl oxygen and the nearest aromatic proton
in ortho-position of the benzene ring. Possible reasons for different helical twisting power of (Z)-(5R)-methyl-2-(4-phenylbenzylidene)cyclohexanone and the E-and Z-arylidene derivatives of 1R, 4R-isomenthone in the mesophase are discussed based on the results of molecular structure studies for these compounds.
In the text below the unsaturated ketones under study will be called “arylidene cyclohexanone derivatives” for convenience
of comparing the characteristics of methylcyclohexanone and isomenthone derivatives.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 962–972, June, 2006. 相似文献
19.
Usova E. B. Lysenko L. I. Zavodnik V. E. Yablonskaya E. K. Krapivin G. D. 《Russian Chemical Bulletin》2003,52(9):2022-2028
6-Acetyl-3(5)-furylcyclohex-2-enones were prepared by condensation of furan-containing chalcones with acetylacetone. Acetylcyclohex-2-enones were subjected to C-methylation. Studies by IR and 1H NMR spectroscopy demonstrated that the resulting compounds occur predominantly in the enol form both in solutions and in the crystalline state. The molecular structure of 6-acetyl-3-(2-furyl)-5-phenylcyclohex-2-enone was established by X-ray diffraction analysis. 相似文献
20.
M. Madesclaire P. Coudert V. P. Zaitsev J. V. Zaitseva 《Chemistry of Heterocyclic Compounds》2006,42(4):506-511
A series of isomeric 2-oxazolidinones has been synthesized from (1S, 2S)-2-amino-1-(4-nitrophenyl)-1,3-propanediol.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 579–584, April, 2006. 相似文献