1) Chiral crown ethers are synthetic macrocyclic polyethers that bind protonated chiral primary amines with high selectivity and affinity. They have been widely used to separate or distinguish the enantiomers of chiral compounds containing a primary amino moiety by high-performance liquid chromatography, capillary electrophoresis, and NMR spectroscopy. In this paper, two important chiral crown ethers including chiral binaphthyl unit and (18-crown-6)-2,3,11,12-tetracarboxylic acid as chiral selectors are focused. And several chiral resolution techniques and their applications in chirotechnology using these chiral crown ethers with related chiral recognition mechanism studies are reviewed. Especially, it was shown that the commercially available HPLC columns based on (18-crown-6)-2,3,11,12-tetracarboxylic acid have been developed and successfully applied for the resolution of various primary amino compounds including amino acids.

A new convenient derivatization method of α-amino acid esters as nitrobenzoxadiazole (NBD) derivatives for chiral resolution was introduced and the enantiomer separation of α-amino acid esters as NBD derivatives was performed by normal HPLC using chiral columns based on polysaccharide derivatives. The NBD derivatives were readily prepared by stirring NBD-Cl and α-amino acid methyl ester HCl with NaHCO 3 in ethanol. The performance of Chiralpak IA was superior to the other chiral stationary phases for enantiomer resolution of NBD derivatives of several α-amino acid methyl esters. Owing to fluorescence detection as well as strong UV absorption, it is expected that the convenient analytical method developed in this study will be very useful for enantiomer separation of α-amino acid esters as NBD derivatives on polysaccharide-derived chiral columns.