Preparative Resolution of Enantiomers in LC

The chromatographic separation of racemates was originally developed for obtaining pure enantiomers of chiral compounds not accessible by the classical routes. Examples are the preparation of the enantiomers using lactose [122-124], cellulose [125] and starch [126] as chiral packings. 

The early systematic preparative enantioseparations of drugs performed on cross-linked chiral polyacrylamides in low-pressure LC mode clearly showed that even this non-opti-mal technique, from the viewpoints of performance and costs, may be useful for comparative biomedical studies of enantiomers of chiral drugs. 

Several chiral drugs were first obtained in enantiomerically pure form using this technique, such as the diuretics chlorthalidone [127] and benzothiadiazines [128], the benzo-diazepinone oxazepam [129], the muscle relaxant chlormezanone [130], hypnotic and anticonvulsant methaqualone [131], the anti-inflammatory drug oxindanac [132], and the antiaromatase fadrozole [133]. 

New developments in chiral chromatography (more universal, easily available, stable, tailor-designed CSPs) and technology (recycling, displacement and especially, SMB) makes chromatography a valuable alternative to classical techniques for the preparation of pure enantiomers. 

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