Reaction of 7-ethoxycarbonyl-1, 3, 5-cycloheptatrine with palladium(II) acetate afforded 2- and 4-formylbenzoic acid ethyl ester and diethyl maleate via aromatization, and a mixture of position isomers of the cycloheptatriene through hydrogen-shift. The reaction with 7-cyano-1, 3, 5-cycloheptatriene was also investigated. The reactions are considered to proceed through palladium complexes of the cycloheptatrienes and their norcaradiene isomers.