A 'One-Shot' strategy for preparative chiral sub/supercritical fluid chromatography with chiroptical detection...

The advantages of a streamlined SFC chiral workflow for preparative chromatographic resolution of the enantiomers of investigational new compounds for pharmaceutical discovery on 10-20 mg scale with on-line chiroptical detection is described. The workflow has been designed to supply milligram amounts of enantiopure material using a universal gradient elution approach. Implementation of a faster and more labor efficient chiral purification workflow was the primary objective, with the secondary objective being an on-line collection of stereochemical information for separated enantiomers with the return of weighed compounds with acceptable purity. Column selection is carried out by gradient analytical SFC screening of six columns in 20 mins, while preparative resolution is carried out in a single injection using an 8-minute gradient with on-line polarimetric detection to assign and confirm the unique optical rotations of each of the eluted enantiomers. Additionally, electrospray ionization mass spectrometry detection is employed to facilitate fraction collection as well as product identification. The new workflow was piloted over a several month period and has proved to be an effective strategy for small scale preparative enantioseparations. Although these smaller-scale chiral separations currently constitute only a sixth of submissions in our laboratory, the one-shot workflow offers clear advantages for rapidly providing enantiopure material for initial in-vitro testing, reducing purification and evaporation cycle times and labor requirements.