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91.
From methyl-5-acetylamino-7,8-anhydro-4,9-O-bis-(t-butyldimethylsilyl)-3,5-dideoxy--D-glycero-D-galacto-2-nonulopyranosidonic acid methylester (1) the derivatives1 a and1 b were obtained by removing the 9-O-(t-butyldimethylsilyl)group withBu
4NF, followed by acetylation. Treatment of1 b with 80% acetic acid and acetanhydride/pyridine yields the 8-epi-N-acetylneuraminic acid derivative2 a and the 7-epi-N-acetylneuraminic acid derivative3 a in a ratio of 3:1 (Scheme 1). The structure elucidation of2 b was achieved by converting2 b via the 4,9-bis-O-(tBDMSi)-8-O-tosyl-derivative2 d into the epoxide1 (Scheme 2). Using the same sequence the epoxides4 and5 were transformed into theN-acetylneuraminic acid derivative6 a and the 7,8-bis-epi-N-acetylneuraminic acid derivative7 a (Scheme 3). After treatment with sodium hydroxide and 0.025m HCl and Dowex 50 H+ the 8-epi-, 7-epi- and 7,8-bis-epi-N-acetylneuraminic acids2,3, and7 were obtained. These three compounds were tested withCMP-N-acetylneuraminic acid synthetase.
Herrn KollegenK. Schlögl mit den besten Wünschen zum 60. Geburtstag. 相似文献
92.
Halfsandwich Complexes of Chromium with the Trifluoromethyl Isocyanide Ligand The synthesis and properties of the halfsandwich complexes [η6-1,3,5-C6H3(CH3)3]Cr(CO)2(CNCF3), [η6-1,3,5-C6H3(CH3)3]Cr(CO)(CNCH3)(CNCF3) und [η6-1,3,5-C6H3(CH3)3]Cr(CNCF3)3 is reported. The vibrational spectroscopic data proof the strong π accepting character of the trifluoromethyl isocyanide ligand. 相似文献
93.
V. V. Lipson V. V. Borodina M. G. Shirobokova S. M. Desenko O. V. Shishkin R. I. Zubatyuk 《Chemistry of Heterocyclic Compounds》2007,43(4):490-495
Interaction of 3-amino-5-methylpyrazole, 3-amino-5-methylthio-, and 3,5-diamino-1,2,4-triazole with Meldrum’s acid, acetone,
ethyl methyl ketone, and cyclohexanone leads to alkyl-substituted pyrazolo[3,4-b]pyridin-6-ones and 1,2,4-triazolo[1,5-a]pyrimidin-7-ones
respectively. The structure of 5,5-dimethyl-2-methylthio-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidin-7-one was demonstrated
by an X-ray structural investigation.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 595–601, April, 2007. 相似文献
94.
95.
J. Díaz-Ferrero M.C. Rodríguez-Larena L. Comellas B. Jiménez 《Trends in analytical chemistry : TRAC》1997,16(10):1865-573
The usual methods for determining polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) are generally expensive and time consuming. This fact has favored the development of faster and cheaper techniques, based on immunoassays and bioassays. This paper reviews these bioanalytical methods and their analytical importance at the present moment. 相似文献
96.
L. I. Zakharkin I. M. Churilova G. N. Antonova P. V. Petrovskii N. S. Ikonnikov 《Russian Chemical Bulletin》1994,43(8):1360-1362
Alkylation of cyclododecanone with ,-dibromoalkanes Br(CH)
n
Br (n=3, 4, 5) under conditions of phase-transfer catalysis in the presence of KOH results in the formation of either bicyclic ketones forn=3 and 5 or a mixture of bicyclic and spirocyclic ketones forn=4.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1436–1438, August, 1994. 相似文献
97.
E. V. Gorobetz A. N. Kasatkin A. V. Kutchin G. A. Tolstikov 《Russian Chemical Bulletin》1994,43(3):466-470
Hydroalumination of methyl nopol ether with a LiAlH4-3AlBr3 system is accompanied by a skeleton rearrangement and gives 6-dibromoalumo-7-methoxymethyl-2-menthene. Further hydroalumination affords a mixture of 2,6- and 2,5-bis(dibromoalumo)-7-(methoxymethyl)menthanes in 8020 ratio. Hydrolysis and oxidation of these organoaluminum compounds were carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 506–510, March, 1994. 相似文献
98.
N. I. Golovina R. F. Trofimova L. O. Atovmyan A. G. Korepin P. V. Galkin G. V. Lagodzinskaya M. V. Loginova L. T. Eremenko 《Russian Chemical Bulletin》1994,43(3):398-401
The reaction of -fluorosubstituted polynitroalkylaldimines with HCl results in replacement of the fluorine atom by a chlorine atom. The hitherto unknown -chlorosubstituted polynitroalkylaldimines have been obtained, and their X-ray structural investigation has been performed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 440–443, March, 1994. 相似文献
99.
T.Ya. Gorbach G.Yu. Rudko P. S. Smertenko S. V. Svechnikov M.Ya. Valakh 《Applied Physics A: Materials Science & Processing》1994,58(2):183-186
Visible room-temperature luminescence of Anisotropically Chemically Etched (ACE) silicon under spontaneous chemical surface modification in HNO3:HF solution is reported. The material is investigated by SEM, AES, IR transmission and Raman scattering methods. 相似文献
100.
The membrane-water partition coefficient of the detergent C12E7 between water and C12E7/POPC mixed membranes has been determined by means of steady-state fluorescence spectroscopy. The emission spectra of the fluorescent probe Laurdan were used as an indicator of membrane composition at different membrane concentrations in the sample. The partition coefficient expressed as the ratio of the mole fractions of the detergent in the membrane and water phases is about 6*105 at low molar ratios of C12E7/POPC (R
c
) and decreases rapidly with increasingR
c
. The limiting detergent content of the lamellar phase (R
c
*
>0.8) is indicated by a minimum ofP(R
c
). 相似文献