Use of Synthetic Metalloporphyrins as Oxidation Catalysts

Abstract

AbstractWhile heme enzymes use iron porphyrin (heme) as the prosthetic group, a variety of metal ions can be introduced into the porphyrin ring to produce metalloporphyrin complexes. In addition to the change of the central metal ions, we are able to synthesize the porphyrin bearing many types of substituents. Thus, the use of synthetic metalloporphyrin complexes is not limited to model reactions of heme enzymes such as peroxidase and P‐450. Although a major concern of this review is oxidations catalyzed by metalloenzymes, many oxidants such as iodosylbenzene (C6H5IO),m‐chloroperbenzoic acid (mCPBA), and sodium hypochlorite (NaOCl) can be used in addition to hydrogen peroxide and reductive oxygen activation as observed for P‐450. In early part of this article, the use of metalloporphyrin as synthetic model systems of heme enzymes is discussed. Preparation and characterization of high valent oxo‐metal intermediates are reviewed in detail. Then, applications of synthetic metalloporphyrins as catalysts for oxidation reactions are described. Highly efficient, robostic against the heme destruction, and stereo‐ and enantioselective reaction systems are the major concerns.