Copper-Catalyzed Trifluoromethylation of Terminal Alkenes through Allylic C–H Bond Activation

An unprecedented type of reaction for Cu-catalyzed trifluoromethylation of terminal alkenes is reported. This reaction represents a rare instance of catalytic trifluoromethylation through C(sp3)–H activation. It also provides a mechanistically unique example of Cu-catalyzed allylic C–H activation/functionalization. Both experimental and theoretical analyses indicate that the trifluoromethylation may occur via a Heck-like four-membered-ring transition state.