Recent Progress in Syntheses of Higher 3-Deoxy-2-ulosonic Acids and Their Derivatives

Higher 3-deoxy-2-ulosonic acids are a family of widely distributed natural high carbon carbohydrates, of which 3-deoxy-Δ-arabino-hept-2-ulosonic acid (DAH), 3-deoxy-Δ-manno-oct-2-ulosonic acid (KDO, 2), 3-Deoxy-Δ-glycero-Δ-galacto-non-2-ulosonic acid (KDN) and 5-acetamido-3,5-dideoxy-Dglecero- Δ-galacto-non-2-ulosonic acid (N-acetylneuraminic acid) are the most common members. These sugars have been demonstrated to play vital roles in a series of biochemical and biological processes.The family of ulosonic acids has provided potential therapeutic leads in developing inhibitors of corresponding enzymes. Zanamivir (5) is a transition state analogue of 2,3-didehydro-2-deoxy-Nacetylneuraminic acid (Neu5Ac2en), which exhibits high inhibitory activity to influenza neuraminidase (NA) and has been approved for the treatment of influenza. Therefore, the syntheses of these ulosonic acids themselves and their analogs have attracted considerable interest in recent years, and become a current research topic. Herewith the recent progresses in the synthesis of these ulosonic acids and their derivatives are reviewed.