Synthesis of a hexasaccharide that relates to the arabinogalactan epitope Original Research Article

A hexasaccharide derivative of the arabinogalactan epitope, methyl β-d-galactopyranosyl-(1→6)-[α-l-arabinofuranosyl-(1→3)]-β-d-galactopyranosyl-(1→6)-β-d-galactopyranosyl-(1→6)-[α-l-arabinofuranosyl-(1→3)]-α-d-galactopyranoside, was synthesized efficiently using a 3+3 strategy. The key step is the preparation of the trisaccharide donor, isopropyl 2,3,4,6-tetra-O-benzoyl-β-d-galactopyranosyl-(1→6)-[2,3,5-tri-O-benzoyl-α-l-arabinofuranosyl-(1→3)]-2,4-di-O-benzoyl-1-thio-β-d-galactopyranoside, from isopropyl 1-thio-β-d-galactopyranoside using a one-pot synthesis of a 3,6-differentially protected building block.