SYNTHESIS OF A TETRASACCHARIDE AND A HEXASACCHARIDE DONOR CORRESPONDING TO THE NONREDUCING TERMINI OF MYCOBACTERIAL 3-O-METHYLMANNOSE POLYSACCHARIDE (MMP)

The blockwise synthesis of the title compounds, namely the tetra-and t he hexasaccharide trichloroacetimidates (20) and (23), is described. B oth acetates and imidates were employed as glycosyl donors in most of the coupling reactions. As nearly all of the synthetic intermediates c ontain one or more OCH3 groups, they are easily identified by NMR spec troscopy the methyl signals. The fully functionalized compounds 20 and 23 correspond to the non-reducing terminal fragments of mycobacterial 3-O-methylmannose polysaccharide (MMP), and can serve as suitable bui lding blocks for the synthesis of higher-order structures of MMP.