Polymer-supported syntheses of oxo-crown ethers and derivatives containing α-amino-acid residues

A simple polymer-supported cyclization-cleavage method is described for the small-scale synthesis of macrocyclic oligomers, with from 12 to 18 ring atoms per repeat unit, which are either 2-oxo-crown ethers, or derivatives containing, except in one case, chiral α-amino-acid residues. In each case the major cyclic product was isolated and characterized. In all except one case this was the cyclic monomer. If the macrocyclic oligomers are needed either for the preparation of static or dynamic combinatorial libraries or for entropically-driven ring-opening polymerizations, all members of the family are of interest as they all react through equilibration to give the same final products.