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

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.