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 CH(3)OH attack at the aromatic ring (occurring at the radical cation stage for 2 and the dication stage for 1) rather than CH(3)OH-induced cyclopropane ring opening, which is estimated to be exothermic by 20 kcal/mol. Although ring-opened products are detected in some instances, these are found to arise from subsequent reaction of the primary oxidation products. These observations are consistent with a proposed product-like transition state for the nucleophile-induced ring opening of cyclopropylarene radical cations in which the positive charge is localized on the cyclopropyl group and nucleophile, and thus unable to derive stabilization from the aromatic ring.
Wang
Yonghui
Y
Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0212.
McLean
Karen H.
KH
Tanko
J. M.
JM