On-bead combinatorial approach to the design of chiral stationary phases for HPLC

A library of 36 L-amino acid anilides, which are potential selectors for chiral HPLC, was synthesized in solution and attached to functionalized macroporous polymer beads. The best selector from the library was identified by a deconvolution process using the HPLC separation of several racemic N-(3,5-dinitrobenzoyl)-alpha-amino acid alkylamides as a probe. In each deconvolution step, a series of chiral stationary phases (CSPs) containing a subset of the amino acid anilide selector library was screened for enantioselectivity. After the best CSP was chosen, the library was further deconvoluted until the single best selector was found. The highest selectivity was obtained with a L-proline-1-indananilide that exhibited alpha values up to 23 under normal-phase HPLC conditions. In addition, six CSPs were prepared using individual selectors from the library, and screening results indicate that the deconvolution process indeed led to the most selective receptor.