Preparation of a New Chiral Pyridino-Crown Ether-Based Stationary Phase for Enantioseparation of Racemic Primary Organic Ammonium Salts

Three novel enantiomerically pure chiral pyridino-18-crown-6 ligands [ ( S, S )-7, ( S, S )-8 and ( R, R )-9 ] containing a linker with a terminal carboxyl function were prepared. One of them [ ( R, R )-9 ] containing two tert -butyl groups at the stereogenic centers was covalently attached to silica gel by an amide bond using 3-aminopropyltrimethoxysilane. The resulting chiral stationary phase [ ( R, R )-11 ] separated the enantiomers of racemic α-(1-naphthyl)ethylammonium perchlorate and 1-phenylethylammonium perchlorate by high-performance liquid chromatography.