Hypervalent iodine(iii)-mediated ring-expansive difluorination of alkynylcyclopropanes en route to the synthesis of difluorinated alkylidenecyclobutanes

Abstract

Described herein is a hypervalent iodine(III)-mediated ring-expansive difluorination of alkynylcyclopropanes using commercially available Olah's reagent (HF·Py) as the fluorine source. The approach allows the facile synthesis of difluorinated alkylidenecyclobutanes with mild reaction conditions and moderate to good yields. Mechanistic studies suggest that the reaction occurs via regioselective 1,2-fluoroiodination of a triple bond followed by a Wagner–Meerwein-type rearrangement.