Intramolecular Cyclization of Aryloxenium Ions. C-O-C and C-C Bond Formation. A Novel Ortho Effect

Article abstract of DOI:10.1021/jo00145a055

o-Aryloxenium ions undergo intramolecular C-O-C bond formation readily as shown by the cyclizations yielding dibenzofurans. m-Aryloxenium ions cyclize via C-C bond formation provided the molecule can adopt the appropriate conformation for ring closure to occur.When an oxygen atom is ortho to the ?-aryl cation center, cyclization to form five- or six-membered rings does not occur and this is attributed to an interaction between oxygen and the positive charge that imposes an unfavorible conformation for cyclization on the aryloxy or arylalkyloxy side chain.