Mechanism and Selectivity in Nickel-Catalyzed Cross-Electrophile Coupling of Aryl Halides with Alkyl Halides

The direct cross-coupling of two
different electrophiles, such
as an aryl halide with an alkyl halide, offers many advantages over
conventional cross-coupling methods that require a carbon nucleophile.
Despite its promise as a versatile synthetic strategy, a limited understanding
of the mechanism and origin of cross selectivity has hindered progress
in reaction development and design. Herein, we shed light on the mechanism
for the nickel-catalyzed cross-electrophile coupling of aryl halides
with alkyl halides and demonstrate that the selectivity arises from
an unusual catalytic cycle that combines both polar and radical steps
to form the new C–C bond.