Synthesis and Reactions of Triptycene-Derived Bromocalix[5] arenes: Conformational Transformation from Cone to 1,2-Alternate

Triptycene-derived p-dibromocalix[5]arene was synthesized by a fragment-coupling approach, whereas treatment of the triptycene-derived calix[5]arene containing three p-tert-butyl phenol groups and a 1,8-dimethoxytriptycene moiety with excess bromine in dichloromethane at room temperature produced triptycene-derived p-pentabromocalix[5]arene directly. Methyl etherification and Suzuki coupling reactions were then carried out. As a result, a series of triptycene-derived calix[5]arene derivatives in fixed cone and 1,2-alternate conformations were obtained. Moreover, conformation transformations of triptycene-derived calix[5]arenes from cone to 1,2-alternate forms could also be achieved.