Alkyltriflones in the Ramberg-Bäcklund Reaction: An Efficient and Modular Synthesis of -Difluoroalkenes.

The unprecedented synthesis of -difluoroalkenes through the Ramberg-Bäcklund reaction of alkyl triflones is described herein. Structurally diverse, fully substituted -difluoroalkenes that are difficult to prepare by other methods can be easily prepared from readily available triflones by treatment with specific Grignard reagents. Experimental and computational studies provide insight into the unique and critical role of the Grignard reagent, which serves both as a base to remove the α-proton and as a Lewis acid to assist C-F bond activation.