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1.
Abstract Methyl 6-deoxy-6-fluoro-β-d-galactopyranoside has been obtained by treatment of methyl β-d-galactopyranoside with diethyl-aminosulfur trifluoride (DAST). Improvements over the existing syntheses of methyl 2, 3-di-O-benzyl-4-deoxy-4-fluoro-β-d-galacto-pyranoside from the corresponding 6-O-substituted 4-O-arylsul-fonyl-d-gluco derivatives are described. 13C NMR spectra of a series of methyl deoxyfluoro-β-d-galactopyranosides and their per-O-acetyl derivatives have been measured. The data obtained can be used as an aid for the interpretation of 13C NMR spectra of deoxyfluoro-β-d-galactopyranose-containing oligosaccharides and related substances. 相似文献
2.
Abstract 3, 6-Di-O-methyl-d-glucose was prepared via 5-O-allyl-1, 2-O-isopropylidene-3-O-methyl-αd-glucofuranose and was converted into 2, 4-di-O-acetyl-3, 6-di-o-methyl-dD-glucopyranosy 1 chloride. Condensation of the chlorosugar with methanol or allyl 2, 3-O-isopropylidene-α-l-rhamnopyranoside gave the corresponding crystalline β-glycbsides. The allyl 4-O-(2,4-di-O-acetyl-3, 6-di-O-Tnethyl-β-dD-glucopyranosyl)-2, 3-O-isopropylidene-α-l-rhamnopyranoside was converted into the title compounds and into crystalline 2, 3-di-O-acetyl-4-O-(2, 4-di-O-benzyl-3, 6-di-O-methyl-β-d-glucopyranosyl)-l-rhamnopyranosyl chloride which should serve as an intermediate for the synthesis of the trisaccharide portion of the major glycolipid of Mycobacterium leprae. 相似文献
3.
Péter Fügedi 《Journal of carbohydrate chemistry》2013,32(3):377-398
Abstract Two approaches were used for the synthesis of 4-O-(α-l-rhamno-pyranosyl)-d-glucopyranuronic acid (1). Rhamnosylation of benzyl 6-O-allyl-2,3-di-O-benzyl-β-d-glucopyranoside (7), followed by deallylation, oxidation to uronic acid, and deblocking afforded 1. Alternatively, rhamnosylation of suitably protected d-glucuronic acid derivatives (25 and 26) gave the protected pseudoaldoBiouronic acid derivatives (19 and 30), which were deprotected. Rhamnosylations were performed in high stereoselectivity without neighbouring-group assistance using 2,3,4-tri-O-benzyl-1-O-trichloroacetimidoyl-α-l-rharnnopyranose (27) with tri-fluoromethanesulfonic acid catalysis. 相似文献
4.
Alicia Fernández Cirelli Marcos Sznaidman Lucio Jeroncic Rosa M. de Lederkremer 《Journal of carbohydrate chemistry》2013,32(2):167-176
Abstract Partial benzoylation of l-rhamnono-l,4-lactone (1) gave 2,5-di-O-benzoyl-l-rhamnono-1,4-lactone (2) as the main product. In similar conditions, d-mannono-l,4-lactone (3) gave preferentially 2,5,6-tri-O-benzoyl-d-mannono-l,4-lactone (4). 2,3,5,6-Tetra-O-benzoyl- (5) and 3,6-di-O-benzoyl-d-mannono-1,4-lactone (6) were isolated in low yield from the reaction mixture. The structures of the partially benzoylated compounds 2, 4 and 6 were assigned on the basis of spectroscopic data. 相似文献
5.
Donald E. Kiely Jamil W. Talhouk James M. Riordan Kathy Gray 《Journal of carbohydrate chemistry》2013,32(4):427-438
Abstract Acid hydrolysis of 6-deoxy-1,2-O-isop ropylidene-α-d-xylo-hexo-furanos-5-ulose (4) yielded gummy 6-deoxy-d-xylo-hexos-5-ulose (1) as an isomeric mixture of two furanose forms, 6-deoxy-α-d-xylo-hexo-furanos-5-ulose and 6-deoxy-β-d-xylo-hexofuranos-5-ulose, and a pyranose structure 1R, 5R-6-deoxy-d-xylo-hexopyranos-5-ulose. The combined percentage (64%) of the furanoses represents an unusually large amount of free carbonyl form for a sugar when compared to simple hexoses and 2-hexuloses. Isomeric structures were determined in deuterium oxide solution by 1H and 13C NMR. 相似文献
6.
Abstract The proton and carbon nuclear magnetic resonance spectroscopic data for methyl 4-O-α-d-glucopyranosyl-[6-O-a-u-glucopyranosyl]-β-d-glucopyranoside (1), a model for the branch-point trisacch-aride of amylopectin, have been analysed using 2-D-heteronuclear correlated spectroscopy. Similar data are presented for the related disaccharide structures methyl β-d-maltopyranoside and β-d-isomal topyranoside. 相似文献
7.
Burdica Ljevaković Jaroslav Horvat Branimir Klaić Srdanka Tomić 《Journal of carbohydrate chemistry》2013,32(3):263-278
Abstract Fully protected 1-thioglycopyranosyl esters of N-acylamino acids (5, 6, and 7) were prepared by condensation of methyl 2, 3, 4-tri-O-acetyl-1-thio-β-d–glucopyranuronate (1), 2, 3, 4-tri-O-acetyl-1-thio-l–arabinopyranose (2), and 2, 3, 4-tri-O-acetyl-1-thio-D-arabinopyranose (3) with pentachlorophenyl esters of N-acylamino acids in the presence of imidazole. The 13C NMR chemical shifts of the starting 1-thio sugars and the 1-thiol ester products are reported. 相似文献
8.
Abstract 2-Deoxy-d-arabino-hexose (1), 2-acetamido-2-deoxy-d-glucose (2), and 2-deoxy-2-trifluoroacetamido-d-glucose (3) were each treated with 1,1-dimethoxycyclohexane or 1,1-dibenzyloxycyclohexane in 1,4-dioxane in the presence of p-toluenesulfonic acid. The major products were the 1,1-dimethyl or 1,1-dibenzyl acetals (4-9) of 3,4:5,6-di-O-cyclohexylidene-2-deoxy-aldehydo-d-arabino-hexose, and of 2- (acylamino)-3,4:5,6-di-O-cyclohexylidene-2-deoxy-aldehydo-D-glucose. The dibenzyl acetal derivatives were converted, by hydro-genolysis, into the corresponding, acyclic aldehydes (10-12) in good yields. 相似文献
9.
Abstract The reaction of 1,2:3,4-di-O-isopropylidene-6-O-triflyl-α-d-galactopyranose (4) with N, N-diphenyl-hydrazine in boiling benzene produced 6-deoxy-1,2:3,4-di-O-isopropylidene-6-(N', N'-diphenylhydrazino)-α-d-galactopyranose (2). The Pyrex-filtered irradiation of 2 in distilled 2-propanol produced 6-amino-6-deoxy-1,2:3,4-di-O-isopropylidene-α-d-galactopyranose (5) and carbazole. The results obtained show that, while this procedure is a feasible route for aminodeoxy sugar synthesis, product yields are too low for this synthesis to be of general value. 相似文献
10.
Abstract Reductive cleavage of the glycosidic carbon-oxygen bonds of methyl 2,3,4,6-tetra-O-methyl-β-d-glucopyranoside (1), methyl 2,3,4,6-tetra-O-methyl-α-d-glucopyranoside (2), permethylated cellulose (6) and permethylated cyclohexaamylose (7) was carried out in the presence of deuteriotriethylsilane, and the configuration of deuterium in the l-deuterio-1,5-anhydro-d-glucitol derivatives (4, 5 and 9, 10) that were produced was established by 1H- and 2H-NMR spectroscopy. All reductions were carried out with boron trifluoride etherate as the catalyst as originally reported [D. Rolf and G. R. Gray, J. Am. Chem. Soc., 104, 3539 (1982)], as well as with trimethylsilyl trifluoromethanesulfon-ate which we now report efficiently catalyzes the regiospecific reductive cleavage of glycosides. Spectroscopic studies revealed that the configuration of deuterium in the products was independent of the configuration of the starting glycoside. The predominant (~95%) axial configuration observed leads us to propose that free oxonium ions (3 and 8) are formed as intermediates in these reductions. 相似文献
11.
Abstract The trichloroacetimidate method has been applied to the construction of α-d-galacto- and α-d-glucopyranosides. The readily available β-trichloroacetimidates of 2,3,4,6-tetra-O-benzyl-d-galacto- and glucopyranose (1-β and 3-β, respectively) have been employed in glycosidations with several monosaccharides (either A, B, C or D) under varying experimental conditions. With the galactose derivative 1-β as a donor and each of the monosaccharides A-D as acceptors, the corresponding disaccharides 1A-1D, were obtained in high yield and with good α-stereoselectivity when employing diethyl ether as solvent and either trimethylsilyl- or tert-butyldimethylsilyl trifluoro-methane sulphonate as catalyst. Glycosidations with the glucose derivative 3-β, as donor, and with the monosaccharide acceptors A, B or D, gave the corresponding disaccharides 3A, 3B and 3D, in high yield but with somewhat lower α-diastereoselectivity than observed with the galactose derivative 1-β. The stereochemical outcome of the reactions is rationalised in terms of possible reaction mechanisms. 相似文献
12.
The reaction of the sodium salt of methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-α-D-galacto-2-nonulo-pyranosonate with a variety of 6-bromo-6-deoxy-D-hexopyranosides, such as methyl 2,3,4-tri-O-acetyl-6-bromo-6-deoxy-α-D-glucopyranos-ide, -galactopyranoside, allyl 2,3,4-tri-O-acetyl-6-bromo-6-deoxy-β-D-glucopyranoside, and allyl 2-acetamido-3,4-di-O-acetyl-6-bromo-2,6-dideoxy-β-D-glucopyranoside, gave the corresponding (2→6)-linked disaccharides, α-glycosides of 2-thio-N-acetylneuraminic acid derivative in good yields. These disaccharides were converted, via O-deacetylation, followed by hydrolytic removal of the ester group, into the title compounds. 相似文献
13.
Abstract 1,5-Anhydro-2,3,6-tri-O-methyl-d-glucitol (1) is formed as the major product in the reductive cleavage of permethylated 4-linked glucopyranosyl residues, but a small amount of 1,4-anhydro-2,3,6-tri-O-methyl-d-glucitol (2) is formed as an artifact when water is present. The formation of 2 can be minimized by carrying out the reductive cleavage under anhydrous conditions. The independent synthesis of 2 and its 5-O-acetyl derivative (4) is described. 相似文献
14.
Ramesh H. Shah 《Journal of carbohydrate chemistry》2013,32(1):139-146
D-Erythrose was synthesized in four steps from D-ribono-1,4-lactone via the 3,5-O-benzylidene derivative of the latter compound. Reduction of the benzylidene D-ribonolactone, and periodate cleavage of the resulting 3,5-O-benzylidene-D- ribitol were performed in a one-flask reaction. The ensuing 2,4-O-benzylidene-D-erythrose was hydrolyzed with 10% acetic acid to obtain syrupy D-erythrose. 相似文献
15.
Dusan Miljković Nada Vukojević DuŜAn Minie Pavle Hadzcircć Gordana Hajduković 《Journal of carbohydrate chemistry》2013,32(3):501-508
Abstract 1,2-O-Cyclohexylidene-α-d-xylofuranuronic acid (2) has been converted into its 3-O-acetyl derivative and consecutively to the corresponding acid chloride and ethyl ester. Direct reaction of 2 with ethanol in the presence of p-to-luene sulphonic acid gave the ethyl ester. Reaction of 2 with phosphorus pentachloride in dry ether gave the acid chloride of 1,2-O-cyclohexylidene-3-O-dichlorophosphoryl–α-d-xylofuranuronic acid. Conformational data have been obtained from 1H and 13C NMR measurements. 相似文献
16.
Nikolai V. Bovin Sergei E. Zurabyan Anatoly Ya. Khorlin 《Journal of carbohydrate chemistry》2013,32(3):249-262
Abstract A study was made concerning the effect of substituants at 0-3, 0-4 and 0-6 of d-galactal and d-glucal (1, 5-anhydro-2-deoxy-d-lyxo- and -d-arabino-hex-1-enitol, respectively) on the double bond reactivity in the chloroazide addition reaction. Results from the quantum chemical calculations of the model structures (ab initio) and also of the whole cyclic molecules in the half-chair conformation (MINDO-3) together with the reaction indices of olefin carbon atoms are presented. These studies snow that (1) the double bond reactivity and the chloroazide addition mechanism are only affected by the substituent at 0-3; (2) the influence of the acyl group is only due to its inductive effect; (3) no interaction between the acyl and the olefin fragments through space was detected. Three 0-acetyl-di-0-benzyl-d-galactals were synthesized. 相似文献
17.
Methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-2-S-acetyl-3,5-di-deoxy-2-thio-D-glycero-α-D-galacto-2-nonulopyranosonate (2) was prepared via methyl 5-acetamTdo-4,7,8,9-tetra-O-acetyl-2-chloro-2,3,5-trideoxy-D-glycero-α-D-galacto-2-nonulopyranosonate (1) and was converted into the sodium salt (3). Condensation of 3 with n-alkyl bromides gave the corresponding methyl (alkyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-thio-D-glycero-α-D-galacto-2-nonulo-pyranosid)onates, which were converted, via O-deacetylation and hydrolysis of the methyl ester group, into the title compounds. 相似文献
18.
Ronan van Rijsbergen Marc J.O. Anteunis André De Bruyn 《Journal of carbohydrate chemistry》2013,32(4):395-404
Abstract Pyridinium p-toluenesulfonate (PPTS) is a reagent of choice for the selective removal of an O-isopropylidene group in a 1,6-anhydro-β-d-aldohexopyranose, where the remaining OH-group is protected. 相似文献
19.
Peter D. Hoagland Helmut Pessen George G. Mcdonald 《Journal of carbohydrate chemistry》2013,32(3):495-499
Abstract The aminolysis of diethyl xylarate was found to proceed through intermediate lactones. In dimethyl sulfoxide at 30°C in the presence of etha-nolamine/ the 1,5-diester is rapidly converted into ethyl d, l-xylaro-1,4-lactone, which reacts with the primary amine to give ethyr N-(2-hydroxyech-yl)-d, l-xylaramide. This compound then forms N-(2-hydroxyethyl)-d, l-xylara-mide-2T5-lactone, which in turn reacts with ethanolamine to produce the final product, N,N'-bis-(2-hydroxyethyl)-d-l-xylaramide. This sequence of reactions was established by 13C NMR spectroscbpy. 相似文献
20.
Fumio Numata Hideharu Ishida Keiko Nishimura Isao Sekikawa Ichiro Azuma 《Journal of carbohydrate chemistry》2013,32(1):127-138
Five monoesters, 6-O-mycoloyl-α, α-treha lose (TMM), 6-O-mycoloyl-D-glucose (GlcM), 6-O-mycoloyl-N-acetyl-D-glucosamine (GlcNAcM), 5-O-mycoloyl-D-arabinose (AraM) and 6-O-mycoloyl-D-galactose (GalM), were synthesized by use of mycolic acid isolated from Mycobacterium tuberculosis strain Aoyama B. Their toxicity and macrophage activating ability were examined in mice. A single intravenous administration of 400 μg of TMM in 9% oil-in-water emulsion killed 8 of 8 treated mice. The other analogs showed less lethal toxicity to mice at the same dose. Tumoricidal activity of mouse peritoneal macrophages was induced by intraperitoneal injection of TMM, GlcM, and GlcNAcM, respectively. 相似文献