are obtained from 5-(co-iodoperfluoropropyl)furan-3(2H)-one and unsaturated compounds through an annulation process (favored 6-exotrig). Yields observed appear as largely depending on the nature of the unsaturated substrate used. For primary alkynols or alkenols or allyl oxycoumarin, the annulation process largely predominates over the radical chain addition process. The contrary is observed when the