Strategies for the Construction of Bimacrocycles

If the two-step syntheses for bimacrocyclic concave reagents are compared with one another, the use of a pyridine-free macrocycle as the starting material seems to be attractive because numerous macrocycles are easily available, some of which can even be purchased. Consequently, for instance calixarenes have been spanned with pyridine (and other) bridges. Although a very powerful ligand for a copper(I) catalyst has been found 

Thus a pool of concave reagents has been made available using one or another of these three general strategies. Some of these molecules have been attached to dendrimers or polymers to allow easier recovery.  

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