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.

Abstract

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<i>-O-</i>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<i>-</i>glycosyl azide analogues. A similar reaction of butyl-3,6-anhydro-5<i>-O-</i>benzoyl<i>-</i> 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 <i>N</i>-glycosyl amide starting from d-glucose derived precursors.