High performance liquid chromatographic enantioseparation of chiral bridged polycyclic compounds on chiralcel OD-H and chiralpak OT(+).
The HPLC enantiomeric separation of 29 racemic bridged polycyclic compounds was examined on commercially available Chiralcel OD-H and Chiralpak OT(+) columns. The separations were evaluated under normal-phase mode (hexane containing mobile phase) for Chiralcel OD-H and under normal-phase as well as under reversed-phase mode (pure MeOH, temperature 5 degrees C) for Chiralpak OT(+). Almost all compounds were resolved either on Chiralcel OD-H or on Chiralpak OT(+), in some cases on both. The use of trifluoroacetic acid (TFA), as modifier of the hexanic mobile phase, had a beneficial effect on the enantioseparation of some polar and acidic compounds on Chiralcel OD-H. The influence of small chemical structural modifications of the analytes on the enantioseparation behavior is discussed. A structure-retention relationship has been observed on both stationary phases. This chromatographic evaluation may provide some information about the chiral recognition mechanism: in the case of Chiralcel OD-H, hydrogen bonding, pi-pi and distereoselective repulsive are supposed to be the major analyte-CSP interactions. In the case of Chiralpak OT(+), a reversed-phase enantioseparation could take place through hydrophobic interactions between the aromatic moiety of the analytes and the chiral propeller structure of the CSP. The synthesis of some unknown racemic bromobenzobicyclo[2.2.1] analytes is also described.
Peluso
Paola
P
Istituto di Chimica Biomolecolare ICB CNR-sezione di Sassari, Traversa La Crucca, 3, Regione Baldinca, I-07040 Li Punti, Sassari, Italy. p.peluso@icb.cnr.it
Cossu
Sergio
S
Moretto
Flavio
F
Marchetti
Mauro
M
D000688:Amylose / Q000031:analogs & derivatives / Q000302:isolation & purification; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D048448:Phenylcarbamates / Q000737:chemistry / Q000302:isolation & purification*; D011083:Polycyclic Compounds / Q000737:chemistry*; D013237:Stereoisomerism
D048448:Phenylcarbamates; D011083:Polycyclic Compounds; C065943:cellulose tris-3,5-dimethylphenyl-carbamate; C080033:Chiralpak AD; D002482:Cellulose; D000688:Amylose