Mercuric triflate-3TMU catalyzed cyclization of ω-alkynoic acids and synthesis of a naturally occurring γ-methylene-γ-lactone

Hg(OTf)(2)(.)3TMU showed efficient catalytic activity for the cyclization of omega-alkynoic acid to give omega-methylene-omega-lactone in excellent yield, and the procedure was efficiently applied for the synthesis of naturally Occurring gamma-methylene-gamma-lactone. The absolute structure of the natural product was established by this synthesis.