Chiral Bis-Urea Embedded Pillararenes with Self-Sorted Planar Chirality.

A new class of chiral bis-urea-embedded pillararenes, each containing two chiral bis-urea units, was synthesized through a modular two-step strategy. Efficient chirality transfer affords well-defined all-pS or all-pR planar chirality, with the corresponding chiroptical responses remaining essentially unchanged over the investigated temperature range. Remarkably, macrocyclization of racemic precursors undergoes spontaneous chiral self-sorting to preferentially afford homochiral macrocycles. This strategy provides a new approach to the generation and stabilization of planar chirality in pillararenes.