The diastereoselective asymmetric total synthesis of NG-391, a neuronal cell-protecting molecule

The stereocontrolled total synthesis of (+)-NG-391, a neuronal cell-protecting molecule, is described along with the determination of its absolute stereochemistry. The following reactions in this synthesis are particularly noteworthy: (1) The stereoselective construction of the conjugated (E,E,E,E,E)-pentaene from an (E,E,E)-alcohol using an IBX oxidation followed by stereoselective Horner–Emmons reaction. (2) The (E)-selective Knoevenagel condensation of a β-ketonitrile with a chiral 2-alkoxyaldehyde prepared from (S)-malic acid. (3) A diastereoselective epoxidation.