Mechanochemical Synthesis of Extended Iptycenes

Iptycenes are intriguing compounds receiving considerable attention as a result of their rigid noncompliant three-dimensional architecture. The preparation of larger iptycenes is often problematic, as a result of their limited solubility and synthetic procedures involving multiple Diels-Alder reactions under harsh extended reaction conditions. We report a mechanochemical synthesis of structurally well-defined iptycenes through an iterative reaction sequence, wherein Diels-Alder reactions and a subsequent aromatization afford higher order iptycenes. We further report that double Diels-Alder reactions under solvent-free condition provide facile access to highly functionalized iptycenes with molecular weights over 2000 Da. Quartz crystal microbalance measurements reveal that these materials efficiently absorb the aromatic hydrocarbons benzene and toluene.