Département de chimie moléculaire

The synthesis of heteroglycoclusters (hGCs) is being subjected to rising interest, owing to their potential applications in glycobiol. In this paper, we report an efficient and straightforward convergent protocol based on orthogonal chemoselective ligations to prep. structurally well-defined cyclopeptide-based homo- and heterovalent glycoconjugates displaying 5-N-acetyl-neuraminic acid (Neu5Ac), galactose (Gal), and/or N-acetyl glucosamine (GlcNAc). We first used copper-catalyzed azide-alkyne cycloaddn. and/or thiol-ene coupling to conjugate propargylated $\alpha$-sialic acid 3, $\beta$-GlcNAc thiol 5, and $\beta$-Gal thiol 6 onto cyclopeptide scaffolds 7-9 to prep. tetravalent homoglycoclusters (10-12) and hGCs (13-14) with 2:2 combinations of sugars. In addn., we have demonstrated that 1,2-diethoxycyclobutene-3,4-dione can be used as a bivalent linker to prep. various octavalent hGCs (16, 19, and 20) in a controlled manner from these tetravalent structures. [on SciFinder(R)]