Tropylation of Azulene, 1-Oxaazulan-2-one, and Their Derivatives, and Electrophilic Reactions of the Tropylazulene Derivatives

The tropylation of azulene, oxaazulan-2-one, and their derivatives was investigated, and various 1 and/or 3-tropylazulenes and 3-tropyloxaazulan-2-ones were obtained. The NMR, UV, and visible spectra of these tropylazulenes were then discussed. Some electrophilic reactions, such as azo-coupling and the acid treatment of four kinds of tropylazulenes, were studied, and it was found that exchanges of the tropyl group and the attacking electrophilies occurred.