PREPARATION AND EVALUATION OF THE CHIRAL STATIONARY PHASES BASED ON N-4-(2,5,6-TRICHLORO-1,3-DICYANO)-PHENYL DERIVATIVES OF L-α-AMINO ACIDS

Abstract

Regioselective functionalization of 2,4,5,6-tetrachloro-1,3-dicyanobenzene (TCDCB) by nucleophilic substitution of the chlorine atom at C(4) for N-L-α-amino acid residue enables preparation of new chiral selectors (1-5). Their binding to aminopropyl silica gel afforded new brush-type chiral stationary phases (CSP-1–CSP-4). Chiral stationary phases CSP-5 and CSP-6 that comprise dipeptide units L-Ala-L-Pro and L-Ala-L-Ala, respectively, were obtained by the solid-state coupling of C(4)substituted derivatives of 2,5,6-trichloro-1,3-dicyanobenzenes 4 and 5 to γ-L-alanylaminopropyl silica gel. Best resolution for some of 23 test racemates was achieved with CSP-4 and CSP-6. This study reveals hydrogen bonding via a sterically exposed amide group and a π-π type interaction via an π-acid persubstituted benzene ring in these CSPs as the main contribution to chiral recognition.