Palladium-Catalyzed Ring-Opening/Defluorinative Annulation of gem-Difluorocyclopropanes With β-Keto Sulfones: Synthesis of Multi-Substituted Furans.

A concise and efficient route to the synthesis of multi-substituted furans has been developed via Pd-catalyzed ring-opening/defluorinative annulation of gem-difluorocyclopropanes (gem-F2CPs) with β-keto sulfones. Control experiments indicated that the reaction proceeds through a linear rather than a branched fluoroalkene intermediate, and further incorporates the C2 and C3 atoms of the gem-F2CP motif into the furan skeletons selectively. Besides, the synthetic utility of this protocol was demonstrated through the modification of bioactive molecules and transformations of furan products into 1,4-epoxynaphthalene derivatives.