Supramolecular chemistry. Isomer distribution as a function of catalyst concentration

The calix[4]resorcarenes belong to an important group of organic molecules in the area of Supramolecular Chemistry. These macrocyclic species can be prepared in good yields through the acid promoted condensation of resorcinol with aliphatic or aromatic aldehydes. In the present work, a synthetic route for the formation of calix [4] resorcarenes containing p-sustituted benzaldehyde moieties are reported. This method involves a AlCl3-induced cyclocondensation process in anhydrous media. The further conversion of the free hydroxyl groups of the octol leads to a mixture of two Isomer compounds which can be separated by fractional crystallization. However, the use of variable concentrations of catalyst modifies the relative proportion of octaethyl octayloxyoctaacetates and resorcarenes with a given cyclic spatial configuration, adequate for the molecular recognition, are obtained.