Rotational isomers of seven peri-substituted 9-(1,1-dimethyl-2-phenylethyl)triptycene derivatives were stereoselectively synthesized and classical kinetics on rotational isomerization were studied. While compounds with relatively small peri-substituents (F and OCH3) showed higher barriers than the peri-unsubstituted one, the peri-chloro compound had almost the same barrier with and those carrying bulkier peri-substituents (Br, CH3, and CF3) showed lower barriers than the peri-unsubstituted one. These apparently anomalous phenomena may be explained in terms of large molecular deformation of these highly congested compounds.
立体选择性合成了7种全取代9-(
1,1-二甲基-2-苯乙基)
三蝶烯衍
生物的旋转异构体,并研究了旋转异构化的经典动力学。虽然具有相对较小的邻位取代基(F 和 O )的化合物比邻位未取代的化合物表现出更高的阻隔性,但邻
氯化合物与带有较大邻位取代基(Br、
CH3 和
CF3)的化合物具有几乎相同的阻隔性比近未取代的障碍更低。这些明显的异常现象可以用这些高度拥挤的化合物的大分子变形来解释。