Amine-Catalyzed Cascade Reactions of Unprotected AldosesAn Operationally Simple Access to Defined Configured Stereotetrads or Stereopentads

An amine-catalyzed cascade reaction of unprotected carbohydrates with 1.3-diketones was elaborated. This cascade is based on a Knoevenagel reaction/intramolecular ketalization/retro-aldol reaction. By application of this operationally simple protocol, a direct access to optically active stereopentads or stereotetrads is given. Rules of configurative outcomes will be discussed.