RADICAL-ION PROBES - 9 - THE CHEMISTRY OF RADICAL CATIONS DERIVED FROM 9-CYCLOPROPYLANTHRACENE AND 9-BROMO-10-CYCLOPROPYLANTHRACENE

Reactions of radical cations generated from 9-cyclopropylanthracene (1 ) and 9-bromo-10-cyclopropylanthracene (2) in the presence of methanol have been investigated electrochemically. The major products arising from oxidation of both substrates are attributable to CH3OH attack at the aromatic ring (occurring at the radical cation stage for 2 and the dication stage for 1) rather than CH3OH-induced cyclopropane ring ope ning, which is estimated to be exothermic by 20 kcal/mol. Although rin g-opened products are detected in some instances, these are found to a rise from subsequent reaction of the primary oxidation products. These observations are consistent with a proposed product-like transition s tate for the nucleophile-induced ring opening of cyclopropylarene radi cal cations in which the positive charge is localized on the cycloprop yl group and nucleophile, and thus unable to derive stabilization from the aromatic ring.