Oligofuranosides containing conformationally restricted residues: Synthesis and conformational analysis

The synthesis of a panel of arabinofuranosyl oligosaccharide analogues (5-13) in which one ring is locked into either the E-3 or E-O conformation is described. The E-3-locked scaffolds 15 and 16 required for the synthesis of 5-10 were prepared in one step from known 1,5-anhydroalditols. A number of routes were explored for the preparation of the E-O-locked monosaccharide derivative 17 needed for the preparation of 11-13. The successful synthesis of 17 was achieved in 17 steps from D-arabinose. Subsequent analysis of 5-13 by H-1 NMR spectroscopy demonstrated that the locked residue does not exert any detectable influence upon the conformers populated by adjacent conformationally unrestricted furanose rings.