Reactions between activated Benzo[a]pyrene and nucleophilic compounds, with possible implications on the mechanism of tumor initiation

Benzo[a]pyrene activated by one-electron oxidation with iodine or ferric ion (an essential component of cytochrome P-450), or by a presumed electrophilic oxygen obtained from the model system ferric chloride and hydrogen peroxide produced cationic species which on subsequent trapping with suitable nucleophiles gave only 6-substituted benzopyrenes. The results implied an appreciable degree of positive-charge localization at the 6-carbon atom in the reactive intermediates of the carcinogenic compound.