Synthesis of a regiospecifically fluorinated polysaccharide 3-deoxy-3-fluoro-(1->6)-alpha-D-glucopyranan via ring-opening polymerization

3-Deoxy-3-fluoro-(1-->6)-alpha-D-glucopyranan (4) was synthesized via deoxyfluorination of 1,6-anhydro-2,4-di-O-benzyl-beta-n-glucopyranose (1) and ring-opening polymerization of 1,6-anhydro-2,4-di-O benzyl-3-deoxy-3-fluoro-beta-D-glucopyranose (2), followed by debenzylation of the resulting 2,4-di-O-benzyl-3-deoxy-3-fluoro-(1-->6)-alpha-D-glucopyranan (3). Partially deoxyfluorinated (1-->6)-alpha-D-glucopyranans were also prepared via copolymerization of 2 with 1,6-anhydro-2,3,4-tri-O-benzyl-beta-D-glucopyranose (6). The assignments of steric arrangements of the C-F bond and stereoregularity of polymers were made from their H-1- and C-13-NMR spectral analysis. The deoxyfluorination at position 3 proceeded with retention of the configuration. The axial C-F orientation and p-anomeric configuration in the C-1(4) conformer of monomer 2 was converted via polymerization to the equatorial C-F orientation and ol-anomeric configuration of the C-4(1) conformer in polymers 3 and 4. Monomer 2 had only a little lower polymerization reactivity than that of 6.