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

In this study we use in situ infrared tracking to describe the kinetics of dual photo- and nickel-catalyzed carboxylate O-arylations. We examined both a state-of-the-art homogeneous (Ir(ppy)3) and heterogeneous (graphitic carbon nitride) photocatalyst, comparing their kinetics to each other, and to the existing mechanistic proposal. We argue against the current hypothesis, specifically that the photocatalyst is only involved to trigger a rate-limiting reductive elimination.