Double Template Synthesis of Giant Macrocycles

The four N-(3,5-dioxyphenyl)acetamide fragments of the macrocyle 11 may be connected not only by oligomethylene chains of various lengths (up to now n 20, corresponding to a total ring size of 100 atoms). Various other structural elements can be incorporated, and connecting chains may also be different in size and 

First a tetraamino calix[4]arene (template I) is used to attach four a,co-bisethylene fragments via urea groups. Thus, the number (four) and, as indicated above, eventually the sequence of the fragments to be connected, is determined. 

A second calix[4]arene, the tetra-tosylurea (template II) is used to bring the reactive groups into the correct position for their connection. 

Metathesis, followed by hydrogenation, converts the heterodimer into a pseudorotaxane. 

After the reaction, a hydrogen bond breaking solvent liberates template II, which can be used again. 

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