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Synthesis of pentasaccharide core structures corresponding to the genus-specific lipopolysaccharide epitope of
P Kosma1, M Strobl, G Allmaier
1Institut für Chemie der Universität für Bodenkultur, Wien, Austria.
Abstract:
The trisaccharides allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->6)-O-2-aceta mid o-2-deoxy- beta-D-glucopyranosyl-(1-->6)-2-acetamido-2-deoxy-alpha- and -beta-D-glucopyranoside (16a and 16b), the tetrasaccharides allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->6)-O-2-aceta mid o-2-deoxy- beta-D-glucopyranosyl-(1-->6)-2-acetamido-2-deoxy-alpha- and -beta-D-glucopyranoside (19a and 19b), and the pentasaccharides allyl O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->8)-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->4)-O-(sodium 3-deoxy-alpha-D-manno-2-octulopyranosylonate)-(2-->6)-O-2-aceta mid o-2-deoxy-bet a -D-glucopyranosyl-(1-->6)-2-acetamido-2-deoxy-alpha- and -beta-D-glucopyranoside (23a and 23b) were prepared. The glycosidic linkages were formed using 1,3,4,6-tetra-O-acetyl-2-chloroacetamido-2-deoxy-beta-D-glucopy ran ose (6) and FeCl3 as promoter as well as per-O-acetylated Kdo mono- and di-saccharide bromide derivatives (12 and 20) under Helferich conditions. The oligosaccharides, which correspond to dephosphorylated part-structures of enterobacterial and chlamydial lipopolysaccharides, were characterized by NMR spectroscopy as well as plasma desorption and matrix-assisted laser desorption mass spectrometry.