Hypervalent iodine-mediated gem-difluorination of vinyl halides enabled by exclusive 1,2-halo migration

β-Difluorinated alkyl halides are of significant value in the modular synthesis of gem-difluorinated molecules. An exclusive 1,2-halo migratory gem-difluorination of vinyl halides with in situ-generated PhIF2·HF is described. This protocol provides a general and practical approach towards a wide variety of β-difluorinated alkyl bromides. Both α-and β-bromoalkyl alkenes are suitable substrates, leading to two distinct types of products. The extension of this protocol to vinyl chloride and iodide are also feasible.The synthetic versatility of this method has been highlighted by the late-stage modification of complex small molecules and further transformations of the β-difluorinated alkyl halides to valuable CF2-containing compounds.