Lewis Acid Promoted Single C–F Bond Activation of the CF3 Group: SN1′‐Type 3,3‐Difluoroallylation of Arenes with 2‐Trifluoromethyl‐1‐alkenes

Activation of the sp³ C-F bond in 2-trifluoromethyl-1-alkenes was accomplished through treatment with a Lewis acid. In the presence of an equimolar amount of EtAlCl₂ , the (trifluoromethyl)alkenes readily underwent an S_N 1'-type reaction with arenes through a Friedel-Crafts-type mechanism via elimination of a fluoride ion to afford 3,3-difluoroallylated arenes in good yields. This selective activation of one C-F bond of the CF₃ group provides a synthetic method for accessing biologically and synthetically important 1,1-difluoro-1-alkenes.