Intramolecular cyclization of alkynoic acids catalyzed by mercury (I1)'and palladium (I1) salts2 provides a convenient method of preparing synthetically and biologically important unsaturated lactones. The development of the cyclization coupled with a carbon-carbon bond-forming reaction which gives a substituted unsaturated lactone may be expected to enhance remarkably the usefulness of this (1)(a) Yamamoto, MJ Chem. SOC., Chem. ...
