Synthetic mucin fragments: synthesis of O-sulfo and O-methyl derivatives of allyl O-(β-d-galactopyranosyl)-(1 → 3)-2-acetamido-2-deoxy-α-d-galactopyranoside as potential compounds for sulfotransferases

Allyl 2-acetamido-4,6-O-(4-methoxybenzylidene)-2-deoxy-α-d-galactopyranoside (1) was condensed with either 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide (2) or 2,3,4-tri-O-benzoyl6-O-bromoacetyl-α-d-galactopyranosyl bromide (14) in the presence of mercuric cyanide. Selective substitution with methyl, sulfo or both at desired positions, followed by the removal of protecting groups, afforded allyl O-(βd-galactopyranosyl)-(1 → 3)-2-acetamido-2-deoxy-6-O-methyl-α-d-galactopyranoside (5), allyl O-(6-O-sulfo-α-d-galactopyranosyl sodium salt)-(1 → 3)-2-acetamido-2-deoxy-6-O-methyl-α-d-galactopyranoside (10), allyl O-(β-d-galactopyranosyl)-(1 → 3)-2-acetamido-2-deoxy-6-O-sulfo-α-d-galactopyranoside sodium salt (13), allyl O-(6-O-sulfo-β-d-galactopyranosyl sodium salt)-(1 → 3)-2-acetamido-2-deoxy-α-d-galactopyranoside (17) and allyl O-(3-O-sulfo-β-d-galactopyranosyl sodium salt)-(1 → 3)-2-acetamido-2-deoxy-α-d-galactopyranoside (22). The structures of compounds 5, 10, 13, 17 and 22 were established by ¹³C NMR and FAB mass spectroscopy.