Restricted Rotation Involving the Tetrahedral Carbon. LXIII. Endeavor toward Enhancing the Rotational Barrier in 9-s-Alkyltriptycenes

Article abstract of DOI:10.1246/bcsj.69.3267

In order to enhance barriers to rotation about the C₉-substituent bond in 9-s-alkyltritpycenes, the secondary alkyl group was modified as well as the peri-substituent. The barrier was slightly enhanced by modifying the substituents but the extent was rather limited. This limitation was attributed to the limitation of the ways of preparation of 9-s-alkyltriptycenes that should give three stable retamers and carry substituents at peri-positions, where only 1,8-difluoro substituents could be used.