The synthesis of monofluoroalkenes using an SN2′ reaction of lithiumamides derived from aromatic amines or lithium thiolates with 3,3-difluoropropenes is reported. This transformation features the use of fluoride as a leaving group.
The Use of Fluoride as a Leaving Group: SN2′ Displacement of a CF Bond on 3,3-Difluoropropenes with Organolithium Reagents To Give Direct Access to Monofluoroalkenes
Lithium is the key to activate the nucleofuge ability of fluoride in the title transformation (see scheme). This simple and straightforward approach not only provides a practical synthetic method for the preparation of monofluoroalkenes, an important fluorinated motif, but also demonstrates the ability of fluoride to act as a competent leaving group in nucleophilic substitution reactions.