Crawling Out of the Chiral Pool: The Evolution of Pirkle-Type Chiral Stationary Phases

The liquid chromatographic separation of enantiomers using chiral stationary phases (CSPs) now enjoys widespread popularity [ 1 ], providing a rapid and convenient method for the analysis of enantiomeric purity and an indispensable tool for the preparative resolution of enantiomers [ 2 ]. Despite considerable recent progress in the understanding of molecular recognition and the design of molecular receptors [ 3 - 5 ], a largely empirical approach to CSP development continues to prevail, with the vast majority of CSPs being derived from readily available “chiral pool” starting materials. Although the convenience and economic advantage of this approach cannot be denied, the resulting products typically offer little or no advantage over existing CSPs. The design and development of CSPs in the laboratories of William H. Pirkle offers an example of how a rational strategy can be applied to the development of useful CSPs and to expansion of the chiral pool.