Total Synthesis of Clerodin

Abstract

The first and asymmetric total synthesis of clerodin, the earliest isolated clerodane diterpenoid, has been achieved by tail‐to‐head cyclization and modular synthetic strategies. The C19 oxidized trans‐decalin core was constructed via a tail‐to‐head cyclization of an epoxide ene‐yne compound containing an internal oxygenated methyl‐bearing alkene. This process involved a titanium(III) catalyzed epoxide ring‐opening/ene‐yne cyclization. The furan fragment was assembled through a metallaphotoredox‐enabled deoxygenative coupling of an alcohol precursor. A SmI2‐mediated elimination of a pre‐installed acetal established the 2,3‐dihydrofuran motif.