A Highly Efficient Approach to [4]Pseudocatenanes by Threefold Metathesis Reactions of a Triptycene-Based Tris[2]pseudorotaxane

A triptycene-based homotritopic host was designed and synthesized. Assembly of the host with a bisbenzylammonium salt containing terminal double bonds resulted in a tris[2]pseudorotaxane, which further performed the threefold metathesis reaction and then hydrogenation to give a [4]pseudocatenane in high yield. The [4]pseudocatenane exhibited a novel topological structure with high symmetry, which was confirmed by the spectral data and X-ray analysis.