Biantennary heptasaccharide

To introduce even greater flexibility, this pair of glycosyl donors (which are activated with the same promoter system) were combined with glycosyl fluorides which in turn can be activated over the SePh/SEt pair in the presence of hafiiocene dichloride/silver triflate [117]. An example applying such selective-activation strategy is the synthesis of the biantennary heptasaccharide of gp63, the major surface glycoprotein from Leishrmnia mexicana amazonensis (Fig. 9) [llg]... 

Several compounds have been described by Lehmann s group which have three sugar (or similar) units separated by spacer groupings. For example, compounds 11 and 12 are both acceptors substrates for l,4-/3-galactosyl transferase comparable to the biantennary core heptasaccharide of A/-glycoproteins. Compounds 13 and 14 and 15-17, which are trisaccharides which mimic galactotetraose and maltopentaose, respectively, have been prepared. 

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