Aryl Halide-Driven Nickel Photocatalytic Decarboxylative Elimination

Nickel photoredox catalytic reactions have found ample application in cross-coupling. However, understanding its mechanistic behavior might identify a bifurcation point, thus allowing for divergent reactivity. In this work, we describe a nickel photoredox decarboxylative <i>β</i>-hydride elimination reaction. Structural-activity analysis of aryl halide additives allowed for tunability, and mechanistic investigations confirm a rate-determining nickel-catalyzed <i>β</i>-hydride elimination step. A consecutive two-photon process yields (<i>Z</i>)-enamides from a combination of decarboxylative elimination and Dexter energy transfer from the same iridium photocatalyst.