145835-75-2Relevant academic research and scientific papers
Synthetic studies toward pyruvate acetal-containing saccharides: En route to the efficient synthesis of Rhizobium-related exopolysaccharide fragments
Eckhardt,Ziegler
, p. 253 - 269 (2007/10/02)
The disaccharide building block benzyl O-{2,3-di-O-benzoyl-4,6-O-[(R)-1-(methoxycarbonyl) ethylidene]-β-D-galactopyranosyl}-(1→3)-2-O-benzoyl-4,6-O-[(5)-1 -(methoxycarbonyl)ethylidene]-α-D-glucopyranoside (13), related to a Rhizobium exopolysaccharide, was prepared by coupling various 4,6-O-[(R)-1-(methoxycarbonyl)ethylidene]-D-galactosyldonors (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]-α-D-glucopyranoside (10) and the corresponding 2,3-O-tetraisopropyldisiloxane-protected glucoside 12. The best results, with respect to β-selectivity and yield of the coupling, were obtained with 5 and 10 in dichloromethane. The β-linked (13) and α-linked (14) disaccharides were efficiently converted via the 1-OH derivatives 17 and 21 into the corresponding trichloroacetimidates 18 and 22. The latter were used for the synthesis of the disaccharide ligands 4,6-(R)-pyruvate-β-D-Galp-(1→3)-4,6-(S)-pyruvate-β-D-Glcp-O(CH2)5NH2 (20), and 4,6-(R)-pyruvate-α-D-Galp-(1→3)-4,6-(S)-pyruvate-β-D-Glcp-O(CH2)5NH2 (24). The corresponding tri- and tetra-saccharide derivatives 4,6-(R)-pyruvate-β-D-Galp-(1→3)-4,6-(S)-pyruvate-β-D-Glcp-(1→4)-β-D-Glcp -O(CH2)5NH2 (28) and 4,6-(R)-pyruvate-β-D-Galp-(1→3)-4,6-(S)-pyruvate-β-D-Glcp-(1→4)-β-D-Glcp -(1→4)-β-D-Glcp-O(CH2)5NH2 (36) were obtained similarly. Disaccharide ligands containing the pyruvate acetal group were successfully synthesized. A Rhizobium-related exopolysaccharide was prepared by coupling various 4,6-O-](R)-1-(methoxycarbonyl)ethylidene]-D-galactosyl donors with benzyl 2-O-benzoyl-4,6-O-](S) -1-(methoxycarbonyl) ethylidene]-α-D -glucopyranoside and the corresponding 2,3-O-tetraisopropyldisiloxane-protected glucoside. The combination that gave the best results was chosen based on β-selectivity and yield of the coupling.
Synthetic Studies toward Pyruvate Acetal Containing Saccharides. Synthesis of the Carbohydrate Part of the Mycobacterium smegmatis Pentasaccharide Glycolipid and Fragments Thereof for the Preparation of Neoantigens
Ziegler, Thomas,Eckhardt, Elisabeth,Birault, Veronique
, p. 1090 - 1099 (2007/10/02)
A series of 2,3-di-O-benzoyl-4,6-O--D-glucopyranosyl donors (β-phenylthio 3, bromide 4, α-chloride 5, β-fluoride 6, and trichloroacetimidate 7) were prepared from the corresponding α-allyl glucoside 1 via the deallylated glucose 2 and were tested in glycosylation reactions with methanol to give the pyruvylated methyl glucosides 8 and 9 and with methyl 2,4,6-tri-O-benzoyl-β-D-glucopyranoside 10 to give the disaccharide 11.Best result with respect to yield and β-selectivity of the coupling were achieved with imidate 7.Thus, the 2-O-benzoyl-4,6-O--3-O-methyl-D-glucopyranosyl trichloroacetimidate 14 was prepared from its benzyl glucoside 12 and used for the synthesis of fragments related to the Mycobacterium smegmatis lipopentasaccharide.Trimethylsilyl trifluoromethanesulfonate-mediated condensation of 14, 5-pentanol, and 10, respectively, followed by deblocking of the products 15 and 17 gave the pyruvylated aminopentyl glucoside 16 and methyl laminaribioside 18.Treatment of 17 with dichloromethyl methyl ether gave the laminaribiosyl chloride 19, coupling of which with protected 5-aminopentanol gave 20 also obtained from 14 and the monosaccharide nucleophile 26.The trisaccharide 5-aminopentyl glycoside fragment 42 was prepared by first coupling of 14 and benzyl 2-O-benzoyl-4,6-O--α-D-glucopyranoside 30 that was converted to the bispyruvylated laminaribiose imidate 33, followed by condensation with thioglycoside 38 obtainable in four steps from 1,2,4,6-tetra-O-acetyl-3-O-benzyl-β-D-glucopyranose to give the trisaccharide ethyl thioglycoside 40.Next, NIS-mediated condensation of 40 and 5-pentanol followed by deblocking gave 42.Pentasaccharide 45 was similarly prepared from 40 and hepta-O-benzoyltrehalose 43 to give first the blocked saccharide 44, deblocking of which afforded the target pentasaccharide.
A novel convergent strategy for the construction of oligosaccharides using TIPS-protected glycosides. Synthesis of fragments related to glycolipids of Mycobacterium smegmatis
Ziegler, Thomas,Eckhardt, Elisabeth
, p. 6615 - 6618 (2007/10/02)
4,6-O-Pyruvylated glucosides 1 were converted to the corresponding glucosyl fluorides 3 and 2,3-O-TIPS-protected glucopyranosides 5, respectively. Lewis-acid-catalyzed coupling of 3 and 5 afforded the pyruvylated disaccharides 6 one of which was further converted via the dissacharide donor 8 to di- and trisaccharide fragments of Mycobacterium smegmatis.
