Palladium-catalyzed acetalization/cyclization of enynones with alcohols: rapid access to functionalized dihaloalkenyl dihydrofurans.

Herein, we report a straightforward method to access alkenyl dihydrofurans via palladium-catalyzed acetalization/annulation from conjugated enynones and alcohols. The reaction undergoes a 5-exo-dig cyclization process, with the formation of four new chemical bonds including two carbon-halogen bonds on the exocyclic alkenyl moiety. Preliminary mechanistic studies suggest that the haloalkyne generated in situ should be involved in this transformation.