SYNTHESIS OF LIGANDS RELATED TO THE O-SPECIFIC ANTIGEN OF SHIGELLA-DYSENTERIAE TYPE-1 .8. SYNTHESIS OF SPECIFICALLY MONOFLUORINATED LIGANDSRELATED TO THE O-POLYSACCHARIDE OF SHIGELLA-DYSENTERIAE TYPE-1

The synthesis is reported of galactopyranose nucleophiles monofluorina ted at positions 3, 4, or 6 and protected by 4,6-O-benzylidene, 3,6-di -O-benzyl, or 3,4-O-isopropylidene groups, respectively. The condensat ion of these nucleophiles with 2,3,4-tri-O-benzoyl-alpha-L-rhamnosyl b romide gave, after deprotection, the disaccharide analogues of methyl O-alpha-L-rhamnopyranosyl-(1 --> 2)-alpha-D-galactopyranoside, monoflu orinated at position 3, 4, or 6 of the galactoside residue.