Synthesis of Lewis x analogues in the form of allyl- and methyl trisaccharides
Seven Lewis X analogues were synthesized in the form of allyl analogues (1, 2, 3) and methyl analogues (4, 5, 6, 7). All glycosylations of the thioglycoside acceptors and the donors were accomplished using 'N'-iodosuccinimide and triflic acid as promoters to form the analogues with the desired [alpha]-fucose/rhamnose linkage. Various deprotection strategies were applied to obtain the target compounds in a high yield. The allyl Lex analogues will be further conjugated to a carrier protein. The methyl Lex analogues will be used as competitive inhibitors in the binding studies. The methyl Lex analogues will also be used for NMR studies to evaluate the solution conformation of the analogues.