Hypersensitive radical probes and the mechanisms of cytochrome P450-catalyzed hydroxylation reactions

The title probes are precursors to kinetically calibrated, arylsubstituted cyclopropylcarbinyl radicals that rearrange with picosecond lifetimes. Appl ications in studies of cytochrome P450-catalyzed hpdroxylation reactions ar e reviewed. Initially confusing results regarding lifetimes of radicals in the hydroxylation reactions were resolved when second-generation probes tha t distinguish between radicals and cations were employed. The results indic ate that two electrophilic oxidizing species are involved in P450-catalyzed hydroxylations, an iron-ore species that inserts oxygen and a hydroperoxo- iron species that inserts OH+. The cationic rearrangement products are ascr ibed to reactions of the protonated alcohol products formed from the latter .