SYNTHESIS OF LD-HEPP AND KDO CONTAINING DISACCHARIDE AND TETRASACCHARIDE DERIVATIVES OF NEISSERIA-MENINGITIDIS INNER-CORE REGION VIA IODONIUM ION PROMOTED GLYCOSIDATIONS

The synthesis of methyl(ethyl) 2-thio-KDO (i.e. 1, 2, 5, 7 and 10) and ethyl 1-thio-LD-Hepp (i.e. 26 and 43) derivatives will be described. The latter derivatives proved to be suitable donors in iodonium ion (NIS/IFOH) promoted glycosidation reactions. The usefulness of the glycosidation approach was illustrated by the successful conclusion of a spacer containing dimer L-alpha-D-Hepp-(1 --> 5)-alpha-KDO-2-O-(CH2)3NH2 (37) and tetramer beta-D-Galp-(1 --> 4)-beta-D-Glep-(1 --> 4)-L-alpha-D-Hepp-(1 -->5)-alpha-KDO-2-O-(CH2)3NH2 (47).