The reactions of three 1-tropylazulenes—ethyl 2-acetamido-3-(cycloheptatrien-7-yl) azulen- 1-carboxylate (I), 2-chloro-1-(cycloheptatrien-7-yl) azulene (II) and ethyl 3-(cycloheptatrien-7- yl)-azulen-1-carboxylate (III)—with phosphorus pentachloride were investigated. The reactions of I and II gave ethyl 2-acetamidoazulen-1-carboxylate and 1, 2, 3-trichloroazulene respectively. On the other hand, III afforded ethyl 3-chloroazulen-1-carboxylate (IV) and (3- ...
