Metalloporphyrins are powerful catalysts capable of a wide variety of chemical transformations. Simple modifications to the catalyst system allow for tuning a catalyst for relatively mild oxidations or more difficult to oxidize substrates. Recently, Zhdankin and coworkers have demonstrated a co-catalyst system with an iron porphyrin with a mixture of iodobenzene and oxone allowing for the quantitative conversion of anthracene to anthroquine (1). This system has also shown promise for the oxidation of alkanes and alkenes such as tetrahydronaphthalene, dihydroanthrane and styrene in moderate yields.
With tuning of the catalyst and reaction conditions, metalloporphyrins are also capable of mild oxidations such as sulfoxidations even in the presence of reactive C-H or alcohol functional groups. Huang and coworkers have used a manganese porphyrin-hypochlorite system for the selective oxidation of glycosyl sulfides to the sulfoxides with high diasteromeric excesses (2). Very little sulfone formation and no oxidation on the sugar occurred. These two recent examples show both the selectivity and powerful oxidation capabilities of metalloporphyrins.
1. Yoshimura, A.; Neu, H. M.; Nemykin, V. N.; Zhdankin, V. V., Metalloporphyrin/Iodine(III)-Cocatalyzed Oxygenation of Aromatic Hydrocarbons. Advanced Synthesis & Catalysis 2010, 352, (9), 1455-1460.
2. Huang, J. Y.; Li, S. J.; Wang, Y. G., Selective Oxidation of Glycosyl Sulfides to Sulfoxides with Sodium Hypochlorite and Catalyzed by Metalloporphyrins. Journal of Carbohydrate Chemistry 2010, 29, (3), 142-153.