Monotosylhydrazone (2) of [2.2.2]cyclophane-1,2-dione (1) decomposed on silica gel, giving the ring-contracted [2.2.1]cyclophane-17-carboxylic acid (4). The electronic spectrum of 4 showed a red shift of the λmax and a broadening of the peak shape in comparison with that of di-p-tolylacetic acid, due to a through-space π–π interaction. Thermolysis of bis(tosylhydrazone) (3) afforded [2.2.2] cyclophan-1-en-1-yl p-toluenesulfonate (6). An intermediate formation of the corresponding[2.2.2]cyclophan-1-yne is suggested.