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 R-(1-naphthyl)ethylammonium perchlorate and 1-phenylethylammonium perchlorate by high-performance liquid chromatography.

Eight new macrocyclic ligands containing the pyrimidine subcyclic unit (3‐10, Figure 1) have been prepared. Two of these new crown ethers are chiral. Pyrimidino‐crowns 3‐8 were prepared by treating the di‐tosylate derivative of the appropriate oligoethylene glycol with 4‐methoxy‐5‐raethyl‐2,6‐pyrimidinedimeth‐anol in basic conditions. The yields were in the 30‐50% range giving the crowns as viscous oils. Chiral dimethyl‐substituted pyrimidino‐crown 9 was prepared from 4‐methoxy‐5‐methyl‐2,6‐pyrimidinedimethyl di‐tosylate and chiral dimethyl‐substituted tetraethylene glycol. Treatment of dimethyl 4‐methoxy‐5‐methyl‐2,6‐pyrimidinedicarboxylate with the diamine derivative of chiral dibenzyl‐substituted tetraethylene glycol gave the chiral dibenzyl‐substituted pyrimidino‐crown diamide 10. Starting 4‐methoxy‐5‐methyl‐2,6‐pyrimidinedi‐methanol was prepared by a six step process from acetamidine hydrochloride and diethyl oxalpropionate.