A Biomimetic Study of Cytochrome P450 Related Oxidations of Toluenes Using Synthetic Hemins
Nakano, T., Agatuma, N., Kodama, S., Kakuda, H., and David Dolphin
Bull. Chem. Soc. Jpn.
A mechanistic study of the oxidation of toluene and its derivatives in a model system designed to mimic cytochrome P 450 (P 450) using iron tetrakis(2,6-dichlorophenyl)-porphyrin chloride (FeTPPCl8Cl) and pentafluoroiodosylbenzene (:C6F5IO) in dichloromethane is reported. The oxidation products were the corresponding benzyl alcohols and aldehydes; no further oxidation products were observed. The relative reaction rates were obtained in competitive reactions including the use of deuterated analogs. In the present model system, Hammett plots and isotope effects indicated conclusively that the rate-determining step was a hydrogen atom abstraction to the oxoiron intermediate which was then followed by a rebound of an OH group. The concerted mechanism and the rebound mechanism were discussed in terms of the differences in reactivities between the model system and natural P 450 enzymes and similar monooxygenation enzymes.