Controllable atom transfer enables photoredox-catalyzed defluorinative alkylation of trifluoromethyl alkenes with polychloroalkanes

Abstract

Polychloroalkanes are commonly used solvents in organic synthesis, in which dichloromethane and chloroform have been intensively applied in radical-mediated alkene functionalization reactions. However, a general and mild protocol for selective activation of C–H and C–Cl bonds of polychloroalkanes via switchable atom transfer processes is still in demand. Herein, we demonstrate a conceptually distinct strategy for alkyl radicals formation from polychloroalkanes through hydrogen atom transfer or halogen atom transfer event under mild photoredox conditions. By this strategy, stoichiometric hazardous reagents and radical initiators are obviated, instead only simple alkyl amines are used as controllable hydrogen- and halogen-atom transfer reagents. The blueprint for radical reactivity is exploited in defluorinative alkylation of α-trifluoromethyl alkenes, thereby providing an entry to synthetically useful polychloroalkylated gem-difluoroalkenes. Moreover, this protocol features simple catalytic systems and operation, gram scale synthesis, modifications of complex molecules, and diverse product transformations.