TfOH-catalyzed intramolecular alkyne-ketone metathesis leading to highly substituted five-membered cyclic enones

The intramolecular carbocyclization of tethered alkynyl ketones to five-membered cyclic enones is shown to be catalyzed by trifluoromethanesulfonic acid in MeOH, proceeding in good to excellent yields and with high selectivities.