Total Synthesis of (-)-Ceforalide B and (-)-Cephanolides B-D.

(-)-Ceforalide B (<b>1</b>) and (-)-cephanolides B-D (<b>2</b>-<b>4</b>) are benzenoid cephanolide diterpenoids possessing the same pentacyclic skeleton, which contains three C₁₃-C₁₅ substituent patterns and different benzylic oxidation states. An olefination/6π-electrocyclization/oxidative aromatization cascade has been verified as divergent access to three C₁₃-C₁₅ patterns. The benzylic aerobic oxidations enabled by the Co(OAc)₂·4H₂O/bromide salt/O₂/PPh₃/<i>N</i>-hydroxyphthalimide system have been developed to deliver expected site-selectivity and different oxidation states. Through the divergent strategy, total synthesis of (-)-ceforalide B and (-)-cephanolides B-D is accomplished.