A disulfated tetrasaccharide fragment with a spacer arm of human hepatocellular carcinoma carbohydrate antigen SB(1a), namely, 2-aminoethyl 3-O-sulfo-beta-D-galactopyranosyl-(1 --> 3)-2-acetamido-2-deoxy-beta-D-galactopyranosyl-(1 --> 4)-3-O-sulfo-beta-D-galactopyranosyl-(1 --> 4)-beta-D-glucopyranoside was synthesized via a [2 + 1 + 1] block building mode. In the last coupling step toward the trisaccharide acceptor 8, benzoyl protected galactosyl bromide donor 14 was found to be much more reactive than the acetyl-protected donors.
Copyright 2002 Elsevier Science Ltd.