Synthesis of the cyclohexane core of phomactins and a new route to the bicyclo[9.3.1]pentadecane diterpenoid skeleton.

Conjugate reduction of an enone accompanied by in situ intramolecular aldol condensation was used to construct the tetrasubstituted cyclohexane nucleus of phomactins. Subsequent relay ring-closing metathesis completed the nine-membered ansa bridge of the diterpenoid framework.