Total Synthesis of Maoecrystal P: Application of a Strained Bicyclic Synthon

A new strategy was devised for the total synthesis of highly oxidized ent‐kauranoids. A highly regio‐ and diastereoselective intermolecular Diels–Alder cycloaddition involving a diene embedded in a substituted bicyclo[4.1.0] skeleton was used to assemble all carbon centers but C17 of the target molecule at an early stage of the synthesis. Subsequent synthetic steps, including redox manipulations, SmI2‐mediated cyclization, and isomerization reactions, afforded the antitumor natural product maoecrystal P. Less is not always more: A strategy involving the incorporation of a substituted cyclopropane ring to generate an overbred intermediate was devised for the total synthesis of the highly oxidized bioactive ent‐kauranoid maoecrystal P. Starting from a strained bicyclo[4.1.0] ketone, a sequence based on intermolecular Diels–Alder cycloaddition, allylic oxidation, SmI2‐mediated cyclization, and late‐stage oxidation reactions led to the target molecule.