Selective C-F bond functionalization of CF3 group represents an appealing strategy for the incorporation of pharmaceutically privileged difluoromethylene moiety. Despite the recent significant advancement attained in the functionalization of Ar-CF3 molecules, prescriptions amenable for alkenyl-CF3 congeners remain sufficiently inadequate. Herein, we report a strategically novel protocol for the C-F bond elaboration of trifluoromethylalkene derivatives. By using readily available allyl metallics as nucleophilic coupling partner, the present reaction enables an expedient construction of structurally diversified CF2 -bridged 1,5-dienes. Furthermore, the exquisite selectivity observed in this transformation is revealed to be based on the underlying mechanism that consists of a cascade of nucleophilic SN 2' defluorinative allylation and electronically promoted Cope rearrangement.