Chemistry of arylalkyl radical cations: Deprotonation vs nucleophilic attack

Radical-cation-mediated oxidation of 9-methylanthracene (9MA) by pyridine/iodine in chloroform produces mainly the product of nucleophilic attack at the open C-10 position. When methyl is replaced by ethyl as in 9-ethylanthracene (9EA), the nucleophilic product is the only one observed. Alternatively, aceanthrene (AA), the 1,9-ethano-bridged equivalent of 9EA, produces mainly the product of side-chain substitution. Stereoelectronic control in the deprotonation is proposed as the rationale for this difference in reactivity, as well as for other radical-cation-mediated oxidations.