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.
[2.2.2]环芳-1,2-二酮(1)的单
甲苯磺酰腙(2)在
硅胶上分解,得到缩环的[2.2.1]环芳-17-
甲酸(4)。与二对甲
苯乙酸相比,4 的电子光谱显示出 λmax 的红移和峰形的变宽,这是由于贯穿空间的 π-π 相互作用。双(
甲苯磺酰腙) (3) 热解得到[2.2.2]环芳-1-en-1-基对
甲苯磺酸酯(6)。建议形成相应的[2.2.2]环芳-1-炔的中间体。