DNMR study of a series of singly peri-substituted 9-(2-methylbenzyl)triptycene derivatives showed that the interconversion among the ap and ±sc rotamers with the o-methyl group pointing outside the triptycyl skeleton occurs by two consecutive gear motion steps by way of the unstable rotamers with the o-methyl group pointing inside. The+sc\ightleftharpoons−sc interconversion barriers (13.2—14.1 kcal/mol) are lower than the ap\ightleftharpoons±sc ones (17.7–20.8 kcal/ mol). The aryl group passes over a peri-hydrogen at the transition state of the former process and over the peri-substituent in the latter.
对一系列单过取代的 9-(2-甲基苄基)三庚烯衍
生物进行的 DNMR 研究表明,邻甲基指向三庚基骨架外侧的 ap 和 ±sc 转子之间的相互转化是通过邻甲基指向骨架内侧的不稳定转子的两个连续的齿轮运动步骤实现的。+sc(ightleftharpoons-sc)的相互转换障碍(13.2-14.1 kcal/mol)低于ap(ightleftharpoons±sc)的相互转换障碍(17.7-20.8 kcal/ mol)。在前一个过程中,芳基在过渡态上穿过一个围氢,而在后一个过程中则穿过一个围取代基。