Palladium-catalyzed synthesis of highly substituted endocyclic enol lactones via a three-component coupling reaction in an ionic liquid

A new, efficient ionic liquid based synthetic procedure was developed for the preparation of highly substituted endocyclic enol lactones via the carbonylation coupling reactions of alkynes and 1,3-diketones in ionic liquid. The reactions proceeded in excellent regioselectivity and in reasonably good yields. The catalyst system can be recycled five times with only modest loss of its catalytic activity.