Synthesis of a tetrasaccharide representing a minimal epitope of an arabinogalactan

The hydrophobic alkyl chain-containing tetrasaccharide, dodecyl β-d-galactopyranosyl-(1→6)-β-d-galactopyranosyl-(1→6)-[α-l-arabinofuranosyl-(1→2)]-β-d-galactopyranoside, was synthesized efficiently using a convergent strategy. In coupling reactions, protected trichloroacetimidates proved to be better donors than their corresponding bromides in the preparation of the dodecyl disaccharide and trisaccharide. Zemplén deacylation provided the target tetramer in good overall yield.