Nilsson U, Ray A K, Magnusson G
Chemical Center, Lund Institute of Technology, University of Lund, Sweden.
Carbohydr Res. 1994 Jan 15;252:137-48. doi: 10.1016/0008-6215(94)90011-6.
The 2-(trimethylsilyl)ethyl (TMSEt) beta-glycosides of the Forssman pentasaccharide [alpha-D-GalNAc-(1-->3)-beta-D-GalNAc-(1-->3)-alpha-D-Gal- (1-->4)-beta-D-Gal-(1-->4)-D-Glc] and the terminal tetrasaccharide, as well as the methyl glycosides 1 and 2 of the terminal di- and tri-saccharides, were synthesised by silver trifluoromethanesulfonate-promoted alpha-glycosylation of suitably protected mono-, di-, tri-, and tetrasaccharide alcohols with 3,4,6-tri-O-acetyl-2-azido-2-deoxy-alpha-D-galactopyranosyl bromide, followed by removal of protecting groups. The anomeric TMSEt group of the Forssman pentasaccharide and terminal tetrasaccharide was removed with trifluoroacetic acid-dichloromethane, to give the corresponding hemiacetal sugars 4 and 6.
福斯曼五糖[α-D-氨基半乳糖-(1→3)-β-D-氨基半乳糖-(1→3)-α-D-半乳糖-(1→4)-β-D-半乳糖-(1→4)-D-葡萄糖]及其末端四糖的2-(三甲基硅基)乙基(TMSEt)β-糖苷，以及末端二糖和三糖的甲基糖苷1和2，通过用3,4,6-三-O-乙酰基-2-叠氮基-2-脱氧-α-D-吡喃半乳糖基溴对适当保护的单糖、二糖、三糖和四糖醇进行三氟甲磺酸银促进的α-糖基化反应合成，随后除去保护基团。用三氟乙酸-二氯甲烷除去福斯曼五糖和末端四糖的异头TMSEt基团，得到相应的半缩醛糖4和6。
