Synthesis and Properties of Extremely Stable Tris(6-methoxy-1-azulenyl)methyl Cation and a Series of Di(1-azulenyl)phenylmethyl and (1-Azulenyl)diphenylmethyl Cations Stabilized by Methoxy Substituents
tris(6-methoxy-1-azulenyl)methyl (8), bis(6-methoxy-1-azulenyl)(4-methoxyphenyl)methyl (9a), and (6-methoxy-1-azulenyl)bis(4-methoxyphenyl)methyl (10a) cations and a series of di(1-azulenyl)phenylmethyl and (1-azulenyl)diphenylmethyl cations having methoxy substituents on each phenyl group, i.e., di(1-azulenyl)(4-methoxyphenyl)methyl (9b) and (1-azulenyl)bis(4-methoxyphenyl)methyl (10b) cations and 3-methyl-1-azulenyl
Extremely stable carbocations, tris(6-methoxy-1-azulenyl)methyl, bis(6-methoxy-1-azulenyl)(4-methoxyphenyl)methyl, and (6-methoxy-1-azulenyl)bis(4-methoxyphenyl)methyl cations were prepared and their pKR+ values were determined spectrophotometrically as >14.0, >14.0, and 13.2, respectively. The extreme stability of these methyl cations are attributable to dipolar structures of azulene rings in addition