Cyclopolymerization. Chirality induction for the synthesis of chiroselective corand/ionophore ligands

This article presents several methods to prepare polymeric chiral crown ethers by cyclopolymerization. Chiral templates such as 1,1′‐bi‐2‐napthol, D‐mannitol, L‐threitol, and pyranosidic sugars are very useful for synthesizing the polymers by cyclopolymerization of divinyl ethers, polymers which posses the ability of chiral recognition towards α‐amino acids. The chiral twist of the (R)‐ or (S)‐binaphthyl template induces the main chain to form a chiral, R,R‐ or S,S‐racemo sequence, respectively. Other templates with chiral axis can be also used as a tool for chirality induction in cyclopolymerization and cyclocopolymerization. The initiating system consisting of chiral alkylsulfonic acid and Lewis acid induces the enantioselective cyclopolymerization of a divinyl acetal (37). Chiral diepoxides polymerize regio‐ and stereospecifically with Lewis acid and KOH, and especially the diepoxide originating from D‐mannitol forms a polymer having the character as a new macromolecular ionophore.