Cluster glycosides and heteroglycoclusters presented in alternative arrangements

• Published in: Tetrahedron letters 2018-12, Vol.59 (50), p.4405-4409
• Main Authors: Figueredo, Andreza S., Zamoner, Luis O.B., Rejzek, Martin, Field, Robert A., Carvalho, Ivone
• Format: Article
• Language: English
• Subjects: CuAAC click reaction; Glycoclusters; Heteroglycoclusters; Iminosugars; Multivalency
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2018.10.069

[Display omitted] •Tetra and hexavalent glycoclusters containing d-glucopyranose cores were synthesised.•Sugars are linked in alternate arrangements through C-1, C-2, C-3 or C-6 positions.•Heteroglycoclusters with non-identical ligands were also obtained.•The iminosugar glycoclusters have trivalent d-glucose attached at C-1 or C-6 positions.•These adducts have potential to resemble pseudooligosaccharides. Multivalent carbohydrates, or glycoclusters, are useful tools to study glycan-lectin and glycan-enzyme recognition processes and have wide potential therapeutic applicability. Herein, we report the synthesis of novel glycoclusters presenting glucopyranose units in alternate arrangements by coupling through the C-1, C-2, C-3 or C-6 sugar positions and using tetra- and hexa-valent scaffolds for multivalent display. Coupling the appropriate azide-functionalised d-glucopyranose units with alkynylated penta- or dipenta-erythritol central cores was accomplished via copper-catalysed azide-alkyne cycloaddition (CuAAC), yielding a panel of eight tetra- and hexa-valent glycoclusters in good yields (52–83%). This click chemistry strategy was extended to the preparation of four heteroglycoclusters using a tris(hydroxymethyl)-aminomethane (TRIS) central scaffold. One unit of either the conventional 1-deoxy-d-nojirymicin iminosugar or its’ C-5 epimeric l-gulo isomer, were incorporated along with three d-glucopyranose units linked through either C-1 or C-6.