Synthesis of an Adamantane-Based Tetralactam and Its Association with Dicarboxamides

Abstract

Tetralactam macrocycles are suitable candidates to be employed as synthetic receptors for charged or neutral guests. In the sensing of neutral molecules, nonpolar solvents such as chloroform or dichloromethane are usually employed so the hydrogen-bonded interactions can be established. Thus, one of the main limitations of the studied macrocycles is their low solubility in those solvents. Herein, we describe the synthesis of an adamantane-based tetralactam macrocycle that is soluble in chlorinated solvents. For this purpose, by following a clipping methodology, we firstly synthesized a kinetically stable pseudorotaxane, constituted by a removable tetraalkylfumaramide thread and the desired macrocycle. A subsequent thermal dethreading straightforwardly yielded the adamantane-based macrocycle. Afterwards, the affinity of this receptor for a series of fumaramide and succinamide guests was studied, calculating the association constants when the corresponding [2]pseudorotaxanes are assembled.