Sequential ring-closing enyne metathesis and intramolecular Diels–Alder reaction: an approach to the synthesis of the core structure of galiellalactone

Development of a route for the synthesis of the core structure of galiellalactone is described. The key step involves a ring-closing enyne metathesis of an allyl propargyl ether to produce a dihydro furano diene with a latent dienophile. The dienophile, when generated from this latent functionality, underwent an in situ intramolecular Diels–Alder reaction to produce the tricyclic skeleton present in galiellalactone. An approach to the construction of the tricyclic core structure of the fungal metabolite galiellalactone is described using a sequence of ring-closing enyne metathesis and intramolecular Diels–Alder reaction.