Phosphine-Catalyzed Remote beta-C-H Functionalization of Amines Triggered by Trifluoromethylation of Alkenes: One-Pot Synthesis of Bistrifluoromethylated Enamides and Oxazoles

An unprecedented phosphine-catalyzed remote beta-C-H functionalization of amine derivatives triggered by trifluoromethylation of an alkene with Togni's reagent was disclosed. This reaction proceeded through the highly selective and concomitant activation of an unactivated alkene and the beta-C-sp3-H bond of an amine derivative, providing bistrifluoromethylated enamides in excellent yields with good regio-, chemo-, and stereoselectivity. Furthermore, the newly developed one-pot protocol provides a facile and step-economical access to valuable trisubstituted 5-(trifluoromethyl)oxazoles. Mechanistic studies showed that this reaction may initiate with a novel phosphine-catalyzed radical trifluoromethylation of unactivated alkene via a phosphorus radical cation.