Total Synthesis of Conjugation-Ready Hyperbranched Pentasaccharide of Clavibacter phaseoli VKM Ac-2641 T by [Au]/[Ag] Catalysis.

Infections by Clavibacter spp. cause an economic burden to farmers. The components present in the cell wall glycopolymers (CWGs) are important for studying the host-pathogen interactions, colonization, and infection. A pentasaccharide containing a hyperbranched Rib f -, Gal f -, and Man p - has recently been identified. Herein, we describe the first total synthesis of the conjugation-ready hyperbranched pentasaccharide of C. phaseoli VKM Ac-2641 T using the [Au]/[Ag]-catalyzed glycosidation chemistry of ethynylcyclohexyl carbonate glycosyl donors. The pentasaccharide was synthesized in a highly convergent fashion from readily accessible monosaccharide building blocks.