Preparative enantioseparation of (±)-N-(3,4-cis-3-decyl-1,2,3,4-tetrahydrophenanthren-4-yl)-3,5-dinitrobenzamide by centrifugal partition chromatography

The racemic compound (±)-N-(3,4-cis-3-decyl-1,2,3,4-tetrahydrophenanthren-4-yl)-3,5-dinitrobenzamide ((±)-1), an analogue of increased lipophilicity of the chiral selector (CS) contained in the Whelk-O® HPLC chiral stationary phase (CSP) has been resolved into its enantiomers by applying centrifugal partition chromatography (CPC). Considering the known enantioselectivity of the Whelk-O® CS for naproxen, and the reciprocity concept in enantioseparation, (S)-naproxen related compounds were tested as CSs. In the search for an adequate solvent system, the partition behaviour of the two solutes, CS and racemate, has been studied using several biphasic solvent mixtures. The optimal CS concentration and sample loading capacity were determined in the chosen solvent system. The search for an appropriate CS and solvent system, the scale-up and optimization of the enantiomer separation by CPC, as well as the rationale for the unexpected elution order of enantiomers, are here described. The comparison of the preparative CPC separation achieved with that in HPLC, using a CSP containing an analogous CS, resulted favourable to the former in terms of loading capacity, solvent consumption and throughput.