Oxidation of caffeine with hydrogen peroxide catalyzed by metalloporphyrins

The biomimetic oxidation of caffeine with hydrogen peroxide using metalloporphyrins as catalysts, which are known to be good biomimetic models of cytochrome P450 enzymes, is investigated. The two manganese porphyrins tested, chloro[5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]manganese(III), [Mn(TDCPP)Cl], and chloro [5,10,15,20-tetrakis(pentafluorophenyl)porphyrinato]manganese(III), [Mn(TPFPP)Cl], afford high conversions of caffeine for all substrate/catalyst molar ratios. Selectivity was found to be dependent on the catalyst employed, and a new spiro racemic compound is described and fully characterized in the solid state from X-ray diffraction studies.