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.