Chiral discrimination of 2-arylalkanoic acids by (1S,2R)-1-aminoindan-2-olthrough the formation of a consistent columnar supramolecular hydrogen-bond network

Enantiopure cis-1-aminoindan-2-ol was selected as a basic resolving agent f or racemic 2-arylalkanoic acids on the basis that its rigid cis-conformatio n would favor the formation of a supramolecular hydrogen-bonded column, in which chiral discrimination of the racemic carboxylate would occur. It was found that this amino alcohol possesses high resolving efficiency for a var iety of racemic acids; also, X-ray crystallographic analyses of the diaster eomeric salts showed that a columnar hydrogen-bond network is formed in bot h the less- and more-soluble diastereomeric salts, as we had expected. A de tailed study on the stabilising interactions suggested that there are two t hat play an important role: (i) hydrogen bonding between the ammonium and h ydroxy groups and the acid carboxylate, which determines the formation of t he columnar network and (ii) CH ...pi, which influences the herringbone pac king of the aromatic groups, implying that it also plays some role in chira l discrimination.