Structural Bias Effect On Azidation at C‑1 and C‑2 of Alkyl-3,6-anhydro‑d‑hexofuranosides: Synthetic Approach to Natural Products and Derivatives

3,6-Anhydro hexofuranose sugars are the structural motif
of natural
product furanodictines A–B and sauropunols A–D, F, and
H. Conversion of the 2-hydroxyl group of alkyl-3,6-anhydro-5-O-benzoyl-d-glucofuranosides to triflate intermediates
followed by azidation reaction yielded 2-deoxy-2-azido derivatives
when the substituents at C-1and C-2 are in cis relation; on the other
hand, in the case of trans substituents, the products were α-glycosyl azide analogues. A similar reaction of butyl-3,6-anhydro-5-O-benzoyl-d-mannofuranosides,
obtained from the corresponding α- or β-d-glucofuranoside
through appropriate oxidation and reduction reactions, yielded only
2-deoxy-2-azido products. We report here in a synthetic approach to
2-substituted sauropunols, furanodictines A–B, and related
analogues, along with 1,4-disubstituted 1,2,3-triazolyl glycoconjugates
and N-glycosyl amide starting from d-glucose
derived precursors.