Zipper polydefluorination-monoborylation of perfluoroalkyl chains

Selective defluorination of perfluoroalkyl chains remains challenging because of the strength of C-F bonds and the inertness of perfluoroalkyl groups. Here, the authors report a zipper reaction that completely defluorinates perfluoroalkylated alkenes into synthetically useful linear alkyl boranes while preserving the carbon backbone. The reaction is scalable and allows the recovery of fluoride in the form of LiF by simple filtration. It can be further applied to gem-difluoroalkenes, which are concluded to be intermediates of the underlying iterative fluoride removal process.