TOWARDS A RATIONAL DESIGN FOR RESOLVING AGENTS .5. SUBSTITUENT EFFECTS IN THE RESOLUTION OF EPHEDRINE USING A SERIES OF CYCLIC PHOSPHORIC-ACIDS

The effects of various aromatic substituents in both ephedrine and a c yclic phosphoric acid on the quality of resolution via diastereomeric salt formation are investigated. The diastereoselective synthesis of a novel series of chloro-substituted ephedrines is described. These chl oroephedrines can be resolved efficiently with some of the cyclic phos phoric acids. By studying the physical properties of nineteen pairs of diastereomeric salts, we show that the quality of the resolution depe nds mainly on the aromatic substituent of the cyclic phosphoric acid, whereas substituents at the phenyl ring of ephedrine play a secondary role.