Photoredox-Neutral Ni-Catalyzed Decarboxylative Fluoroalkylation via Radical Sorting Cross-Coupling

The C(sp3/sp2)-C(sp3) linkages
are undoubtedly important in modern organic synthesis. The number
and variety of oxidative addition-driven photoredox neutral nickel-catalyzed
C(sp3)-C(sp2) couplings have increased significantly
in recent years. However, neutral radical–radical cross-coupling
to form C(sp3/sp2)-C(sp3) bonds remains
an important but elusive goal for engineering coupling reactions,
especially in regulating cross-selectivity. In this article, we report
an efficient photoredox-neutral Ni-catalyzed highly chemoselective
decarboxylative fluoroalkylation via radical–radical cross-coupling
of carboxylic acids and α-CF3 alkyl bromides. Detailed
mechanistic studies elucidated the decarboxylation in an oxidative
process that is orthogonal to α-CF3 alkyl bromide
activation via oxidative addition, and radical sorting of two coupling
partners with different electronic effects offers the possibility
of tuning the rate of radical addition of the two radicals to achieve
good cross-selectivity. A wide range of fluoroalkyl halides and carboxylic
acids bearing a diverse set of substituents were compatible to produce
valuable aliphatic CF3 chiral products under mild conditions.