9-Isopropyltriptycene derivatives carrying a fluoro, chloro, bromo, or t-butyl substituent in a peri-position were synthesized and their dynamic NMR behavior was studied to see the dependence of the barrier to rotation of the bridgehead substituent upon the bulkiness of the peri-substituent. The data obtained in this work together with those reported earlier disclose that, among the derivatives in which the peri-substituent is not buttressed by the 2-substituent, the peri-methoxy compound has the highest barrier and the barrier decreases as the bulkiness of the peri-substituent increases. 1,2,3,4-Tetrachloro and tetrabromo derivatives show the slightly positive buttressing effect.
合成了在peri位上携带
氟、
氯、
溴或叔丁基取代基的9-异丙基三苯并衍
生物,并研究了它们的动态NMR行为,以观察桥头取代基的旋转障碍与peri取代基的体积之间的关系。此研究获得的数据与早期报道的数据结合显示,在未被2-取代基支撑的peri取代基衍
生物中,peri-甲氧基化合物具有最高的旋转障碍,而当peri取代基的体积增大时,旋转障碍减小。1,2,3,4-四
氯和四
溴衍
生物表现出略微正的支撑效应。