Method for the preparation of derivatives of heptiptycene: toward dual-cavity baskets

We have developed a novel synthetic method that enables the preparation of functional derivatives of heptiptycene, i.e., cavitands with two juxtaposed cavities. The homocoupling of bicyclic dibromoalkenes is promoted by Pd(OAc)2 (10%) in dioxane (100 °C) to give cyclotrimers in 27-77% yield under optimized reaction conditions (Ph3P, K2CO3, n-Bu4NBr, N2, 4 Å MS). These dual-cavity baskets show a strong π → π* absorption at 241 nm (ε = 939,000 M(-1) cm(-1)), along with a subsequent fluorescence emission at 305 nm.