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 (RP)-9] containing a linker with a terminal carboxyl functi on 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 p hase [(R%)-11] separated the enantiomers of racemic alpha-(1-naphthyl)ethyl ammonium perchlorate and 1-phenylethylammonium perchlorate by high-performa nce liquid chromatography.