Helianthus-like cucurbit[4]uril and cucurbit[5]uril analogues

Abstract

A new glycoluril-like molecule, cyclopentanopropanediurea (CyP-TD), was prepared by malonic ester synthesis. Its condensation with paraformaldehyde resulted in two Helianthus-like cucurbituril analogues, CyP₄TD[4] and CyP₅TD[5], with cyclopentano groups evenly distributed on the equators. The structures of the two macrocycles were confirmed by ¹H-NMR, HRMS-ES and single-crystal X-ray diffraction. CyP₄TD[4] and CyP₅TD[5] both exhibit excellent thermal stability, and CyP₅TD[5] has better solubility in water and organic solvents, while CyP₄TD[4] can hardly dissolve in them.