Chemical synthesis of a core 2 branched pentasaccharide containing a carboxylate group

Design and synthesis of a carboxylate-containing pentasaccahride 1 with the Galβ(1–4) (Fucα1–3)GlcNAcβ(1–6){3-[1-carboxymethyl]-Galβ(1–3)}GalNAcα–OMe sequence, which is obtained through regioselective coupling of the 6-OH of a novel acceptor 9 with Lewisx donor 10 catalyzed by NIS-TfOH are described.