First synthesis of the immunodominant β-galactofuranose-containing tetrasaccharide present in the cell wall of Aspergillus fumigatus
作者:Mingkun Fu、Guohua Zhang、Jun Ning
DOI:10.1016/j.carres.2004.10.019
日期:2005.1
beta-Galf-(1 --> 5)-p-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-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. (C) 2004 Elsevier Ltd. All rights reserved.