Synthesis of a pyruvylated N-acetyl-β-D-mannosamine containing disaccharide repeating unit of a cell wall glycopolymer from paenibacillus alvei

Abstract

A disaccharide implicated in anchoring of bacterial Surface-layer proteins to secondary cell wall glycopolymers has been prepared by glycosylation of a protected N-acetyl glucosamine acceptor with a glucopyranosyl donor to generate the β-(1→4)-linkage. Subsequent inversion of the configuration and azide introduction at position 2 with triflic anhydride, however, led to formation of a tetrazole derivative. Alternatively, displacement of a 2-O-mesylate by sodium azide, reduction and N-acetylation enabled the conversion into the distal N-acetyl-β-Dmannosamine residue. Pyruvylation of the latter unit and global deprotection afforded the disaccharide repeating unit from Paenibacillus alvei as a ligand for crystallographic and binding studies.