Direct enantioselective separation of some propranolol analogs by HPLC on normal and reversed cellulose chiral stationary phases

The enantiomeric separation of several racemic aryloxyaminopropan-2-ol derivatives related to propranolol on normal and reversed phase of cellulose tris (3, 5-dimethylphenyl carbamate) chiral stationary phases known as Chiralcel OD and Chiralcel OD-R were studied. It was observed that the chiral separation depends on the substitution pattern of the aryl group, i.e., 1-naphthyl, 2-naphthyl, and phenyl group and polarity on the basic nitrogen in the side chain. In both normal and reversed phase modes the (+)-R-enantiomer eluted first in all of the analogs resolved. It can be concluded that: (1) substituents on the side chain did affect the interaction of the enantiomers with the polar carbamate moiety in the CSP; and (2) the dipole-dipole stacking between the pi-donor 3, 5-dimethylphenyl carbamate group pending from the glucose rings of the CSP and pi-acceptor aryl group of the analyte is crucial for the efficient chiral discrimination. The chiral recognition mechanism(s) between these analogs and the chiral stationary phases are proposed. (C) 1996 Wiley-Liss, Inc.