title: Synthesis of a New Series of Sialylated Homo- and Heterovalent Glycoclusters by using Orthogonal Ligations.
abstract: The synthesis of heteroglycoclusters (hGCs) is being subjected to rising interest, owing to their potential applications in glycobiology. In this paper, we report an efficient and straightforward convergent protocol based on orthogonal chemoselective ligations to prepare structurally well-defined cyclopeptide-based homo- and heterovalent glycoconjugates displaying 5-N-acetyl-neuraminic acid (Neu5Ac), galactose (Gal), and/orN-acetyl glucosamine (GlcNAc). We first used copper-catalyzed azide-alkyne cycloaddition and/or thiol-ene coupling to conjugate propargylated α-sialic acid3, β-GlcNAc thiol5, and β-Gal thiol6onto cyclopeptide scaffolds7-9to prepare tetravalent homoglycoclusters (10-12) and hGCs (13-14) with 2:2 combinations of sugars. In addition, we have demonstrated that 1,2-diethoxycyclobutene-3,4-dione can be used as a bivalent linker to prepare various octavalent hGCs (16,19, and20) in a controlled manner from these tetravalent structures.
authors: Université Grenoble Alpes, Département de Chimie Moléculaire (DCM), CNRS, DCM 38000 Grenoble France.
authors: Gour Chand
authors: GC
authors: Daskhan
authors: Université Grenoble Alpes, Département de Chimie Moléculaire (DCM), CNRS, DCM 38000 Grenoble France.
authors: Carlo
authors: C
authors: Pifferi
authors: Université Grenoble Alpes, Département de Chimie Moléculaire (DCM), CNRS, DCM 38000 Grenoble France; Institut Universitaire de France 103 boulevard Saint-Michel 75005 Paris France.
authors: Olivier
authors: O
authors: Renaudet
keywords: cyclopeptides; heteroglycoclusters; homoglycoclusters; multivalency; orthogonal ligations