Asymmetric synthesis of the tricyclic core of cyathin diterpenoids via intramolecular Heck reaction

The tricyclic ketone 1, which displays the ring system of cyathin diterpenes was assembled from 2-methylcyclopentanone through a sequence involving enantioselective Michael addition, intramolecular Heck reaction and trimethylaluminum-promoted one-carbone ring expansion of the C-ring with trimethylsilyldiazomethane.