Photoredox Activation of Inert Alkyl Chlorides for the Reductive Cross-Coupling with Aromatic Alkenes.

The inertness of chloroalkanes has precluded them as coupling partners for cross-coupling reactions. Herein we disclose a general strategy for the activation of inert alkyl chlorides through photoredox catalysis and their use as coupling partners with alkenes. The catalytic system is formed by [Ni(OTf)(Py 2 Ts tacn)](OTf) (1 Ni ), which is responsible for the Csp 3 -Cl bond activation, and [Ir( NMe2 bpy)(ppy) 2 ]PF 6, (PC Ir NMe2 ), which is the photoredox catalyst. Combined experimental and theoretical studies show an in situ photogenerated Ni I intermediate ([Ni(Py 2 Ts tacn)] + ) which is catalytically competent for the Csp 3 -Cl bond cleavage via a S N 2 mechanism for primary alkyl chlorides, forming carbon-centered free radicals, which react with the olefin leading to the formation of the Csp 3 -Csp 3 bond. These results suggest inert alkyl chlorides can be electrophiles for developing new intermolecular strategies in which low-valent aminopyridine nickel complexes act as key catalytic species.