Separation of atropisomeric 1,4,5,6-tetrahydropyrimidinium salts by chiral HPLC and determination of their enantiomerization barriers.
Chiral HPLC separation of a series of novel atropisomeric quaternary (1) and ternary (2) 1,2-disubstituted 1,4,5,6-tetrahydropyrimidinium salts bearing disymmetric aryl groups in positions 1 and/or 2 is described. A screening of different polysaccharide stationary phases (OD-R, OJ-R and AD-RH) and chromatographic conditions allowed for partial or baseline resolution of 16 over 26 compounds. When a semi-preparative separation was achieved, the corresponding enantiomerization barriers were determined employing the off-column method. The experimental data were compared inter se in order to establish the factors influencing the magnitude of the barriers and with those corresponding to the parent amidines.
Magri
María L
ML
Umr 6180 Chirotechnologies: Catalyse et Biocatalyse, University Paul Cézanne, Aix-Marseille III, 13397 Marseille CEDEX 20, France.
Vanthuyne
Nicolas
N
Roussel
Christian
C
García
María B
MB
Orelli
Liliana R
LR
D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D007536:Isomerism; D011743:Pyrimidines / Q000302:isolation & purification*; D013237:Stereoisomerism
D011743:Pyrimidines