Asymmetric Total Syntheses of (+)-5-epi-Schisansphenin B and the Proposed Structure of (+)-15-Hydroxyacora-4(14),8-diene.

Abstract

The asymmetric total syntheses of (+)-5-epi-schisansphenin B and the proposed structure of (+)-15-hydroxyacora-4(14),8-diene have been accomplished from 1,3-cyclopentadione (10) in eight synthetic steps. The enantioselective palladium-catalyzed redox-relay Heck alkenylation, the intramolecular Stetter reaction, and the regioselective Tiffeneau-Demjanov-type ring expansion were the pivotal steps in these syntheses.