Comparative reactivities of esters of oncogenic and nononcogenic purine N-oxides and evidence of the oxidation-reduction reactivity of aromatic nitrenium ions.

Studies on the relative reactivities of esters of oncogenic and nononcogenic members of the purine N-oxide series indicate that, despite similarities in rates of reaction with the solvent, electrophilic cations from oncogenic derivatives are 10- to 100-fold more reactive toward added nucleophiles in vitro than are cations from nononcogenic compounds. The studies provide strong confirmation of an earlier proposal that nitrenium ion contributors of delocalized aromatic cations from 3-acyloxypurines, rather than radical intermediates, are the agents responsible for the oxidizing reactivity of these esters. They demonstrate further that delocalized aromatic nitrenium ions are highly susceptible to reduction by common nucleophiles that are not usually associated with oxidation-reduction reactions. Examples of such behavior with "soft" bases and other oncogenic arylamines indicate the generality of this little recognized property of aromatic nitrenium ions.