Electron Relay Boosts Ruthenium‐Laccase System Photo‐Epoxidation
Claudio Righetti, Antonio Recupido, Mehdi Yemloul, Pierre Rousselot‐Pailley, Ally Aukauloo, Winfried Leibl, Elise Courvoisier‐Dezord, A. Jalila Simaan, Thierry Tron, Yasmina MekmoucheAbstract
We report here the light‐driven oxidation of olefin to epoxide using a [Ru(bipyridine)3]2+/laccase (RuII/LAC3)‐based system, enhanced by the presence of methyl viologen (MV2+) as an electron relay. This approach leads to a fivefold increase in the conversion yield of sodium p‐styrene sulfonate (pSS) oxidation (from 3% to 14% in the presence of MV2⁺), and favors chemoselectivity toward epoxidation. We demonstrate that laccase plays a crucial role in steering product selectivity, favoring epoxidation due to its ability to scavenge superoxide (O2•−). In contrast, in the absence of laccase, the reaction predominantly yields sodium p‐benzaldehyde sulfonate (A) and the sodium α‐hydroxyketone p‐phenyl sulfonate (α‐HK). Mechanistic insights, supported by reactive intermediate trapping, isotope labeling, and product distribution analysis, suggest a reaction pathway involving both molecular oxygen and water as the oxygen sources.