Palladium-Catalyzed Cascade C-H Trifluoroethylation of Aryl Iodides and Heck Reaction: Efficient Synthesis of ortho-Trifluoroethylstyrenes

A palladium-catalyzed selective C-H bond trifluoroethylation of aryl iodides has been explored. The reaction allows for the efficient synthesis of a variety of ortho-trifluoroethyl-substituted styrenes. Preliminary mechanistic studies indicate that the reaction might involve a key Pd-IV intermediate, which is generated through the rate-determining oxidative addition of CF3CH2I to a palladacycle; the bulky nature of CF3CH2I influences the reactivity. Reductive elimination from the Pd-IV complex then leads to the formation of the aryl-CH2CF3 bond.