A PARTIAL REDUCTIVE-CLEAVAGE STUDY OF THE CAPSULAR POLYSACCHARIDE OF ESCHERICHIA-COLI K57

Trideuteriomethylated and methylated derivatives of the capsular polys accharide of Escherichia coli K57 were partially cleaved by Et(3)SiH, using Me(3)SiOSO(2)Me and Me(3)SiOSO(2)CF(3) as catalysts, to produce oligosaccharide-anhydroalditols. The structures of the trideuteriometh ylated trisaccharide- and tetrasaccharide-anhydroalditols isolated wer e established by FABMS and NMR spectroscopy. Although conditions for t he selective production of the tetrasaccharide-anhydroalditol could no t be established, oligosaccharide-anhydroalditols were isolated in suf ficiently high yield to make this an attractive approach for the struc tural elucidation of the repeating units of bacterial polysaccharides.