Chiral Ligand-Exchange Chromatography for Separation of Three Stereoisomers of Octahydroindole-2-carboxylic Acid

A novel HPLC method is described for separation of the three stereoisomers of octahydroindole-2-carboxylic acid (Oic), an intermediate in the synthesis of perindopril. The chiral mobile phase contained the complex of Cu(II) with the optically active selector L-phenylalaninamide (L-PheA), and an ion-pair reagent, sodium 1-octanesulfonate. The effects of the concentrations of the Cu(II)–L-PheA complex and the ion-pair reagent, mobile phase pH, ionic strength, acetonitrile content, and column temperature were studied. Satisfactory resolution was achieved for three stereoisomers, RRR-, SSS-, and SRR-Oic.