Nitrogen‐Oxidized Tröger's Base Macrocyclic Arenes: Unprecedented Enantioselective Recognition in Water

Achieving high enantioselectivity with synthetic receptors, particularly in water, remains a significant challenge despite the success seen in natural biological systems. In this study, we introduce a facile synthesis of Tröger's base (TB)‐containing macrocyclic arenes (TBn), where TB units are linked via methylene bridges, providing the macrocycles with a rigid framework. Oxidation of enantiopure TBn yields corresponding chiral nitrogen oxides (TBnNO) with excellent water solubility, attributed to the high polarity of the N‐O bond, surpassing the pH limitations of traditional ion‐functionalized approaches. Remarkably, TBnNO exhibits exceptional enantioselective recognition toward a wide range of chiral guests in aqueous solution, achieving enantioselectivities as high as 41.0. The underlying mechanism involves a combination of hydrophobic interactions and steric effects caused by rigid chiral cavities. These findings highlight the potential of nitrogen‐oxidized macrocycles as a transformative tool for supramolecular application in water.