Main-Group Lewis Acids for C-F Bond Activation

The significant benefits of fluorinated compounds have inspired the development of diverse techniques for the activation and subsequent (de)functionalization of rather inert, C-F bonds. Although substantial progress has been made in the selective activation of C(sp(2))-F bonds employing transition metal complexes, protocols that address nonactivated C(sp(3))-F bonds are much less established. In this regard, the use of strong main-group Lewis acids has emerged as a powerful tool to selectively activate C(sp(3))-F bonds in saturated fluorocarbons. This Perspective provides a concise overview of various cationic and neutral silicon-, boron-, and aluminum-based Lewis' acids that have been identified to facilitate the heterolytic fluoride abstraction from aliphatiC-Fluorides.; The potential of these Lewis acids in hydrodefluorination as well as defluorinative C-F bond functionalization reactions is highlighted. Emphasis is placed on the underlying mechanistic principles to provide a systematic classification of the individual reactions. Finally, brief insight into the related C-F bond activation chemistry using carbocations or Bronsted acids is presented.