Hemin catalyzed biomimetic oxidative phenol-indole [3+2] reactions in aqueous media

A hemin/H2O2 catalytic system for oxidative phenol–indole [3 + 2] coupling in aqueous solution has been developed, enabling benign synthesis of valuable benzofuroindolines under sustainable conditions. Mechanistic studies revealed the dual role of iron porphyrin responsible for both phenol oxidation and Lewis acid activation, which differs from the well-explored chemistry of hemin in carbene and nitrene insertion reactions. A preliminary experiment with cytochrome c showed that the turnover of iron porphyrin was amenable for a macromolecular setting with remarkable efficiency (ca. 13 300 TON).