201654-02-6Relevant academic research and scientific papers
Radical Ion Probes. 9. The Chemistry of Radical Cations Derived from 9-Cyclopropylanthracene and 9-Bromo-10-cyclopropylanthracene
Wang, Yonghui,McLean, Karen H.,Tanko
, p. 628 - 635 (1998)
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 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.
Radical ion probes. Part 10. Ceric(IV) ammonium nitrate oxidation of cyclopropylarenes
Wang, Yonghui,Tanko
, p. 2705 - 2711 (2007/10/03)
The chemistry of radical cations generated via the oxidation of several cyclopropylarenes with ceric(IV) ammonium nitrate in CH3CN-CH3OH is reported. For cyclopropylbenzene, the major product is 1-phenylpropane-1,3-diyl dinitrate, arising from ring opening of the cyclopropylbenzene radical cation. Experiments with 1-cyclopropyl-4-methylbenzene reveal that ring opening of cyclopropylbenzenes occurs substantially faster than side chain deprotonation. Cyclopropane ring opened products are also formed in the oxidation of 1- and 2-cyclopropylnaphthalenes. For 9-cyclopropylanthracene however, ring opened products are not detected. Instead, all products arising from this reaction are attributable to reaction of nucleophiles with the aromatic ring. Overall, these results confirm and extend earlier observations pertaining to the chemistry of cyclopropylarene radical cations. General principles associated with the use of cyclopropyl groups as "probes" for radical cation intermediates, and general principles governing radical ion ring openings are discussed.
