Thermodynamic Approach for Synthesizing [2]Catenanes from Borate Ion-Containing Crown Ethers and a Macrocyclic Ammonium Ion

In this study, we synthesized [2]catenanes from bis-catechol spiroborate ion-containing crown ethers and a macrocyclic ammonium ion through hydrogen bonding and ion pairing. The borate-forming reaction of bis-catechol and trimethyl borate in the presence of an amino-ether-based macrocycle (amino macrocycle) initially formed face-to-face complexes, which continuously converted into the corresponding [2]catenanes via ring-opening and ring-closing reactions under thermodynamic control.