Acridane[4]Arenes: Scope of the Macro‐Tetramerization, Derivatization Options, and Water‐Soluble Derivatives

Macrocycles are essential scaffolds in supramolecular chemistry, offering versatile platforms for functionalization. Here, we report the optimization, expanded scope, and comprehensive derivatization strategies for acridane[4]arenes (A4A), a large macrocyclic platform featuring a conformationally restricted bowl shape analogous to resorcin[4]arene. The scope of the macrocyclization was expanded with four distinct 'feet' substituents at the lower rim. Strategies for selective functionalization at the upper rim were developed, including N-Boc protection at each acridane subunit. This modification induced self-assembly into a dimeric cage in apolar solvents, which form stable host-guest complexes with tetrabutylammonium salts. Further functionalization of the acridane nitrogen via Buchwald-Hartwig cross-coupling allowed installation of aromatic groups bearing diverse functional handles. Finally, water-soluble A4A derivatives were achieved by introducing charged ionic 'feet' substituents, such as 1-methylimidazolium. These results establish A4As as a highly modular macrocyclic platform with broad potential for supramolecular applications.