A high yielding chemical synthesis of sialyl Lewis x tetrasaccharide and Lewis x trisaccharide; examples of regio- and stereodifferentiated glycosylations
Virtually complete regioselective galactosylation of the diol acceptor p-methoxyphenyl 6-O-benzyl-2-deoxy-2-tetrachlorophthalimido-β-D- glucopyranoside (8) with the donor phenyl 2,3,4-tri-O-acetyl-6-O-benzyl-1- thio-β-D-galactopyranoside (11) gave the lactosamine derivative 14, which was fucosylated with the donor 15 to give the Le(x) trisaccharide glycoside 2 after deprotection. Regioselective si