Page 111 - Chiral Separation Techniques

3.7 Combinatorial Libraries of Selectors for HPLC 87

Scheme 3-7.

with mixed selectors has not been recommended for actual enantioseparations [95],
it is ideally suited for our combinatorial approach to optimized selectors.
As expected from the design of the experiment, the HPLC column packed with
CSP 14 containing all 36 members of the library with π-basic substituents separated
π-acid substituted amino acid amides. Although encouraging since it suggested the
presence of at least one useful selector, this result did not reveal which of the numer-
ous selectors on CSP 14 was the most powerful one. Therefore, a deconvolution pro-
cess involving the preparation of series of beads with smaller numbers of attached
selectors was used. The approach is schematically outlined in Fig. 3-17.

Fig. 3-17. Schematic of the deconvolution process used in the library-on-bead approach.