Efficient and general approach to eremophilanes using siloxyalkyne-alkene metathesis.

An efficient skeletal reorganization of a terminal alkene armed with an appropriate siloxy alkyne fragment is a pivotal step in our novel and general strategy for the construction of a bicyclic core of eremophilanes with complete diastereocontrol and high synthetic efficiency. Our approach features three significant strategic elements. First, the enyne metathesis precursor is assembled via a highly endo-selective Diels-Alder reaction. Second, installation of the siloxy group at the alkyne terminus enables the regioselective assembly of the ensuing enone fragment via intramolecular enyne cyclization. Third, the common enone precursor offers the necessary flexibility of accessing several natural products of the eremophilane family.