Prismarenes: A New Class of Macrocyclic Hosts Obtained by Templation in a Thermodynamically Controlled Synthesis

The novel title macrocycles, based on methylene-bridged 1,5-naphthalene units, have been obtained by template effect in a thermodynamically controlled synthesis. In detail, the prism[5]arene 1 or the prism[6]arene 3 was selectively removed from the equilibrium mixture by using the complementary ammonium-templating agent. When only the solvent 1,2-DCE was used, the 1,4-confused derivative 2 was obtained. The prism[5]arene here described shows a deep pi-electron-rich aromatic cavity that exhibits a great affinity for the quaternary ammonium guests, originating from favorable cation center dot center dot center dot pi and +NC-H center dot center dot center dot pi interactions. This recognition motif is the basis of the templated synthesis of the prism[n]arenes here reported.