Studies of the resolution of racemic 1,1′-bi-2-naphthol with a dipeptide chiral selector identified from a small library

Several new stationary phases were prepared to study the structure-activity relationship of the chiral resolution of racemic 1,1′-bi-2-naphthol with a modified dipeptide Asn-Asn selector. The number of amino acid, the side chain protecting groups of the amino acid, and the Fmoc end-capping group all proved important for enantioselectivity. The linker also influenced enantioselectivity. Influence of the length of the linker appears to be related to the accessibility of chiral selectors. The bond through which the selector is attached to the linker proved important. Based on these results, it is postulated that hydrogen bonding interactions between one side chain amide group of one Asn and the oxygen on the backbone of another Asn with the two hydroxyl groups of the analyte play an important role in the resolution of racemic 1,1′-bi-2-naphthol with the modified dipeptide Asn-Asn selector.