Method for the Preparation of Derivatives of Heptiptycene:
Toward Dual-Cavity Baskets
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Abstract
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)<sub>2</sub> (10%) in dioxane (100 °C) to
give cyclotrimers in 27–77% yield under optimized reaction
conditions (Ph<sub>3</sub>P, K<sub>2</sub>CO<sub>3</sub>, <i>n</i>-Bu<sub>4</sub>NBr, N<sub>2</sub>, 4 Å MS). These
dual-cavity baskets show a strong π → π* absorption
at 241 nm (ε = 939 000 M<sup>–1</sup> cm<sup>–1</sup>), along with a subsequent fluorescence emission at 305 nm