Synthesis of amino and ammonium resorcin[4]arenes as potential receptors

Starting from the resorcin[4]arene tetrabromide (cone conformation) a number of resorcin[4]arene derivatives containing an amino function in the side chains have been prepared. Preliminary investigations, including UV, NMR and MS analyses, of mixtures of the resorcarene and its potential guests, such as metal cations or aminoacids, evidenced promising new properties, dependent on the nature of the substituents. Notably, treatment of 1a with pyridine gave readily the corresponding pyridinium salt 7a, capable of interacting with GaIII salts in aqueous solution. The same results have been obtained starting from the tetrabromide 1b (1,2-alternate conformation) for two of the above reactions, giving derivatives 3b and 7b