抄録
Reactions between tropylium cations and enamines were examined. The reaction of tropylium bromide (I) with pyrrolidine enamine of cyclohexanone in benzene produced 2-tropylcyclohexanone (V) and 2, 6-ditropyl-1-cyclohexylidene pyrrolidinium bromide (IV), whereas the reaction of tropylium fluoroborate (II) with morpholine enamine of the same ketone in aqueous dioxane gave V in almost quantitative yields. Table I summarizes the production of 2-tropyl-substituted ketones by the reaction of II with enamines carried out in aqueous dioxane. The reaction of 7-ethoxy-1, 3, 5-cycloheptatriene (XIII) with enamines in the presence of acetic acid also examined, and participation of two moles of enamine in the reaction was observed on the reaction of XIII with aldehyde enamines. Namely, the reaction of XIII with propionaldehyde enamine and butyraldehyde enamine gave respectively 2-methyl-4-tropyl-2-pentenal (XIV) and 2-ethyl-4-tropyl-2-hexenal (XVII).
