Newcomer to the Calixarene Family: Synthesis and Characterization of Selenacalix[4]arene

In this work, we describe a general and efficient fragment condensation method for the synthesis of monoselenacalix[4]arene as a new member of the broad calixarene family. The key fragments were obtained from the starting <i>p</i>-<i>tert</i>-butylphenol by reaction with <i>in situ</i> generated SeCl₂ or from its formyl derivative by reaction with SeO₂ in pyridine. The availability of both fragments allowed us to test two different independent macrocyclization routes, leading to the final selenacalixarene in good yields. The first successful attempts to immobilize the new system were made, and the basic dynamics of the macrocycles in solution were studied using VT NMR techniques. The selenium analogue of calix[4]arene was successfully immobilized in the <i>cone</i> conformation, suggesting its potential use in supramolecular chemistry.