Electrochemical Aerobic Epoxidation of Styrenes Catalyzed by Manganese Tetraphenylporphyrin

Oxygen atom transfer (OAT) is a useful reaction in chemical synthesis, but because of the low reactivity of O₂ with organic substrates, harsh oxidants are often required. In contrast, metalloenzymes such as Cytochrome P450 catalyze a wide range of OAT reactions under mild conditions with O₂ as the source of the O atoms. In this work, we use a synthetic manganese porphyrin catalyst to mimic this reactivity. Our method enables electrochemical epoxidation of styrenes using O₂ through the generation of a Mn-superoxo intermediate. We report the reactivity of 12 styrene derivatives, with yields impacted by the position and electronic properties of the substituents. Spectroelectrochemical analyses indicate the generation of high-valent intermediates that enable epoxidation under these mild conditions.