Synthesis and Intramolecular Nitrile Oxide Cycloaddition of 3,5‘-Ether-Linked Pseudooligosaccharide Derivatives: An Approach to Chiral Macrooxacycles

3,5‘-Ether-linked pseudooligopentose derivatives were synthesized for the first time from readily available carbohydrate precursors. The 1,2-isopropylidene-protected ether-linked oligopentoses are potentially important as precursors
of novel RNA analogues. Intramolecular cycloaddition of the
nitrile oxides prepared from these derivatives led to the
diastereoselective formation of chiral isoxazolines fused to
10−16-membered oxacycles. The stereochemistry of some of
these isoxazolines was established by X-ray diffraction and
NOESY analysis.