Evidence for Photocatalyst Involvement in Oxidative Additions of Nickel-Catalyzed Carboxylate O-Arylations

Dual photocatalysis and nickel catalysis enable mild cross-coupling, but understanding their in situ kinetics is limited. We studied a model carboxylate O-arylation with Ir(ppy)3 and graphitic carbon nitride. Conditions saturated the nickel cycle with the photocatalyst, isolating intrinsic behaviors. Ir(ppy)3 deactivated the nickel cycle, yielding more dehalogenated side products, indicating turnover-limiting reductive elimination. Graphitic carbon nitride showed higher selectivity, even at high ratios, with aryl halide rate dependence, suggesting oxidative addition’s role in kinetics. These findings challenge the hypothesis that the photocatalyst merely triggers reductive elimination.