Identification of chiral selectors from a 200-member parallel combinatorial library.

Selection of chiral selectors for the resolution of racemic N-(1-naphthyl)leucine ester 1 was studied with a 200-member parallel library prepared on polymeric synthesis resin. Through this study, the library screening procedure developed previously is improved and other pertinent issues concerning the screening process are also addressed. The equilibration time required for screening is reduced from 24 h to approximately 3 h. Excellent correlation of the outcome between the resin batch equilibration experiment and chromatographic separation is further demonstrated. It is also demonstrated that selectors with separation factors as low as 1.4 could be identified by this batch screening process. In addition, a great deal of information regarding enantioselective interactions was obtained in this parallel library study. Such information should prove useful in improving future library designs.