The functionalized, pyruvic acetal-containing haptenic trisaccharide, p-trifluoroacetamidophenyl 6-deoxy-2-O-(3-O-[4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-meth yl- beta-D-glucopyranosyl]-alpha-L-rhamnopyranosyl)-alpha-L-talopyranosid e (19), a component of the glycolipid from Mycobacterium avium serovar 8 was synthesized. For the preparation of the terminal pyruvic acetal-containing unit, benzyl 2-O-benzyl-3-O-methyl-beta-D-glucopyranoside (6) was condensed with methyl 2,2-di(ethylthio)propionate (1) in the presence of SO2Cl2-CF3SO3H catalyst to yield benzyl 2-O-benzyl-4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-methyl-beta -D- glucopyranoside (7S), which was then converted into the suitably substituted glycosyl donor 2-O-acetyl-4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-methyl-alph a-D- glucopyranosyl trichloroacetimidate (11). The disaccharide glycosyl acceptor p-nitrophenyl endo-3,4-O-benzylidene-6-deoxy-2-O-(2,4-di-O-benzyl-alpha-L-rhamnopyrano syl)- alpha-L-talopyranoside (15) was glycosylated with 11 in the presence of trimethyl trifluoromethanesulfonate to furnish the protected trisaccharide p-nitrophenyl 2-O-(3-O-[2-O-acetyl-4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-m ethyl-beta- D-glucopyranosyl]-2,4-di-O-benzyl-alpha-L-rhamnopyranosyl)-endo-3,4- O-benzylidene-6-deoxy-alpha-L-talopyranoside (16). After deprotection, this gave the spacer-armed unprotected haptenic trisaccharide 19.
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http://dx.doi.org/10.1016/0008-6215(94)80059-6 | DOI Listing |
Carbohydr Res
October 2024
Bose Institute, Department of Chemical Sciences, Block EN-80, Sector-V, Salt Lake, Kolkata, 700091, India. Electronic address:
An efficient synthetic strategy has been developed to achieve a pyruvic acid acetal containing tetrasaccharide repeating unit corresponding to the K82 capsular polysaccharide of Acinetobacter baumannii LUH5534 strain in very good yield. The synthetic scheme involves the use of suitably functionalized monosaccharide thioglycosides as glycosyl donors and a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic glycosylation activator to furnish satisfactory yield of the products with appropriate stereochemistry at the glycosidic linkages. Incorporation of the (R)-pyruvic acid acetal in the d-galactose moiety was achieved in very good yield by the treatment of the diol derivative with methyl 2,2-bis(p-methylphenylthio)propionate in the presence of a combination of NIS and triflic acid.
View Article and Find Full Text PDFCarbohydr Res
November 1994
Institut für Organische Chemie und Isotopenforschung, Universität Stuttgart, Germany.
The disaccharide building block benzyl O-(2,3-di-O-benzoyl-4,6-O-[(R)-1-(methoxycarbonyl) ethylidene]-beta-D-galactopyranosyl)-(1-->3)-2-O-benzoyl-4,6-O-[(S)-1- (methoxycarbonyl)ethylidene]-alpha-D-glucopyranoside (13), related to a Rhizobium exopolysaccharide, was prepared by coupling various 4,6-O-[(R)-1-(methoxycarbonyl)ethylidene]-D-galactosyl donors (benzoyl-protected chloride 1, pivaloyl-protected chloride 2, and benzoyl-protected fluorides 3 and 4, and trichloroacetimidate 5) with benzyl 2-O-benzoyl-4,6-O-[(S)-1- (methoxycarbonyl)ethylidene]-alpha-D-glucopyranoside (10) and the corresponding 2,3-O-tetraisopropyldisiloxane-protected glucoside 12. The best results, with respect to beta-selectivity and yield of the coupling, were obtained with 5 and 10 in dichloromethane. The beta-linked (13) and alpha-linked (14) disaccharides were efficiently converted via the 1-OH derivatives 17 and 21 into the corresponding trichloroacetimidates 18 and 22.
View Article and Find Full Text PDFCarbohydr Res
February 1994
Institut für Organische Chemie und Isotopenforschung, Universität Stuttgart, Germany.
The preparation of pyruvate acetal-containing 5-aminopentyl mono-, di-, and tri-saccharide fragments related to serovars 8 and 21 of the species-specific glycopeptidolipid of Mycobacterium avium-intracellulare is described. The saccharides were constructed by sequential coupling of the suitably protected 4,6-O-[(S)-1-methoxycarbonylethylidene]-D-glucopyranosyl trichloroacetimidates 6 and 7 to Z-protected 5-aminopentanol, to give the serovar 21 monosaccharide fragment 9 upon deblocking; and to ethyl 2-O-benzoyl-4-O-benzyl-1-thio-alpha-L-rhamnopyranoside (18), to give the corresponding ethyl 1-thio-disaccharides 21 and 23, respectively. Subsequent N-iodosuccinimide-promoted coupling of the latter with Z-protected 5-aminopentanol followed by deblocking of the products afforded the corresponding disaccharide fragments 26 (serovar 8) and 27 (serovar 21), respectively.
View Article and Find Full Text PDFCarbohydr Res
February 1994
Institute of Biochemistry, Lajos Kossuth University, Debrecen, Hungary.
The functionalized, pyruvic acetal-containing haptenic trisaccharide, p-trifluoroacetamidophenyl 6-deoxy-2-O-(3-O-[4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-meth yl- beta-D-glucopyranosyl]-alpha-L-rhamnopyranosyl)-alpha-L-talopyranosid e (19), a component of the glycolipid from Mycobacterium avium serovar 8 was synthesized. For the preparation of the terminal pyruvic acetal-containing unit, benzyl 2-O-benzyl-3-O-methyl-beta-D-glucopyranoside (6) was condensed with methyl 2,2-di(ethylthio)propionate (1) in the presence of SO2Cl2-CF3SO3H catalyst to yield benzyl 2-O-benzyl-4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-methyl-beta -D- glucopyranoside (7S), which was then converted into the suitably substituted glycosyl donor 2-O-acetyl-4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-methyl-alph a-D- glucopyranosyl trichloroacetimidate (11). The disaccharide glycosyl acceptor p-nitrophenyl endo-3,4-O-benzylidene-6-deoxy-2-O-(2,4-di-O-benzyl-alpha-L-rhamnopyrano syl)- alpha-L-talopyranoside (15) was glycosylated with 11 in the presence of trimethyl trifluoromethanesulfonate to furnish the protected trisaccharide p-nitrophenyl 2-O-(3-O-[2-O-acetyl-4,6-O-(S)-(1-methoxycarbonylethylidene)-3-O-m ethyl-beta- D-glucopyranosyl]-2,4-di-O-benzyl-alpha-L-rhamnopyranosyl)-endo-3,4- O-benzylidene-6-deoxy-alpha-L-talopyranoside (16).
View Article and Find Full Text PDFAnal Biochem
December 1991
Laboratoire de Chimie Biologique, Université des Sciences et Techniques de Lille Flandres-Artois, Villeneuve d'Ascq, France.
The mass spectra of permethylated methyl 4,6-O-(1-carbomethoxyethylidene)-D-hexopyranoside and 1,5-anhydro-D-hexitol of glucose, galactose, and mannose and permethylated methyl 5,6-O-(1-carbomethoxyethylidene)-D-galactofuranoside and 1,4-anhydro-D-galactitol have been determined. The stability of each compound toward methanolysis and reductive cleavage is discussed. These techniques permit the identification of the acetalic linkages of pyruvic acid present in polysaccharides.
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