A screening method for chiral selectors that does not require covalent attachment.
A high-throughput screening protocol is proposed for chiral selector discovery. It is modeled after the protocol for biological screening of candidate drugs from chemical libraries. The procedure works based on target distribution between an aqueous phase and an organic phase. The target may be a racemate or separate enantiomers. Screening for noncovalent intermolecular association between target and candidate selectors is carried out by partitioning experiments in the presence and absence of the candidate chiral selectors in the organic phase (plasticized poly(vinyl chloride)). The partition ratio measurement uses 96-well plates for high throughput. The feasibility of this approach is validated by working with a known target/chiral selector pair, N-(3,5-dinitrobenzoyl)-alpha-phenylglycine and 2,2,2-trifluoro-1-(9-anthryl)ethanol. The validated protocol is applied to a small library of 12 cyclopropyl dipeptide isosteres. Eight bind the racemic target, econazole. Among them, one has measurable chiral selectivity. The advantage of the method is that it does not require the covalent attachment of either the analyte or the selector, and the required amount of the potential chiral selector is about 100 mug.