A novel approach to the synthesis of amino-sugars. Routes to selectively protected 3-amino-3-deoxy-aldopentoses based on pyridinium salt photochemistry

A new approach for the synthesis of selectively blocked 3-amino-3-deoxyaldopentoses is presented. The strategy is based on employment of a pyridinium salt photocyclization-aziridine ring-opening sequence to prepare stereo-chemically defined, enantiomerically enriched aminocyclopentendiol derivatives. Ring-opening reactions transform these substances into terminally differentiated aminopolyols, which serve as precursors to the target aminoaldopentoses. The utility of this strategy is demonstrated by its application to the syntheses of protected derivatives of D- and L-3-amino-3-deoxyxylose, L-3-amino-3-deoxyarabinose, and a late-stage intermediate in a potential route to N-acetylneuraminic acid.