Synthesis of an analogue of the marine polypropionate tridachiahydropyrone.

[reaction: see text] A novel approach to the formation of the unusual pyrone-containing ring systems as found in polypropionate metabolites from the Tridachia family of marine molluscs has been developed. This approach includes an intramolecular cyclization of a beta-keto acid onto a cyclohexenone ring to afford a fused, bicyclic pyrone.