Access to 3‑<i>O</i>‑Functionalized <i>N</i>‑Acetylneuraminic Acid Scaffolds

Direct access to 3-<i>O</i>-functionalized 2-α-<i>N</i>-acetylneuraminides and their corresponding 2,3-dehydro-2-deoxy-<i>N</i>-acetyl­neuraminic acid derivatives is described. Initially, a stereoselective ring-opening of the key intermediate <i>N</i>-acetylneuraminic acid (Neu5Ac) 2,3-β-epoxide with an alcohol provided the 3-hydroxy α-glycoside. <i>O</i>-Alkylation of the C3 hydroxyl group generated novel 3-<i>O</i>-functionalized Neu5Ac derivatives that provided the corresponding unsaturated derivatives upon elimination.