First synthesis of the immunodominant beta-galactofuranose-containing tetrasaccharide present in the cell wall of Aspergillus fumigatus.
beta-Galf-(1-->5)-beta-Galf-(1-->6)-alpha-Manp-(1-->6)-alpha-Manp, the immunodominant epitope in the cell-wall galactomannan of Aspergillus fumigatus, was synthesized for the first time as its allyl glycoside. The key disaccharide glycosyl donor, 2,3,5,6-tetra-O-benzoyl-beta-D-galactofuranosyl-(1-->5)-2-O-acetyl-3,6-di-O-benzoyl-beta-D-galactofuranosyl trichloroacetimidate (10), was constructed by 5-O-glycosylation of 1,2-O-isopropylidene-3,6-di-O-benzoyl-alpha-D-galactofuranose (4) with 2,3,5,6-tetra-O-benzoyl-beta-D-galactofuranosyl trichloroacetimidate (5), followed by 1,2-O-deacetonation, acetylation, selective 1-O-deacetylation, and trichloroacetimidation. The target tetrasaccharide 16 was obtained by the condensation of allyl 2,3,4-tri-O-benzoyl-alpha-D-mannopyranosyl-(1-->6)-2,3,4-tri-O-benzoyl-alpha-D-mannopyranoside (14) as glycosyl acceptor with the disaccharide glycosyl donor 10, followed by deprotection.
Fu
Mingkun
M
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, PO Box 2871, Beijing 100085, China.
Zhang
Guohua
G
Ning
Jun
J
D001232:Aspergillus fumigatus / Q000737:chemistry*; D002240:Carbohydrate Sequence; D002473:Cell Wall / Q000737:chemistry*; D005663:Furans / Q000737:chemistry*; D005690:Galactose / Q000737:chemistry* / Q000276:immunology; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry* / Q000276:immunology
D005663:Furans; D009844:Oligosaccharides; D005690:Galactose