Chirbase: A molecular database for storage and retrieval of chromatographic chiral separations

In order to meet the strong demand for storage and retrieval of chiral separations, we have developed Chirbase a database built on Chembasee from Molecular Design Limited, a very powerful and well spread software. Chirbase allows the selection of the most promising conditions for a given chiral separation by searching and retrieving at the same time molecular fragments issued from the compound and from the stationary phase. The obtainment of optically pure compounds and the control of their optical purity cover the scope of various very active fields of research. Enantiomerically pure compounds can be obtained through various routes which involve chiral discrimination (ref. 1): -isolation from natural products (chiral pool) -asymmetric synthesis -enzymatic resolution of racemates or enzymatic reaction -crystallization or chromatography of diastereomeric -preparative chromatography of racemates on chiral on prochiral compounds. compounds obtained by reaction of a racemate with an optically active compound. stationary phases (CSP) recently reviewed by Francotte et a1 (ref. 2). The control of the optical purity of the compounds obtained through the above mentioned techniques can be performed using different methods: NMR experiments, polarimetry or analytical chromatography on a suitable CSP, the later method being far more accurate than the two other (ref. 3). Chromatography of racemic or scalemic compounds on a CSP (chiral chromatography) is a field of research in expansion since the last 15 years in order to meet the strong demand in chiral issues (ref. 4a, 4b, 4c). The basic principle of the chromatographic chiral separation rests on the energy difference in the two labile diastereomeric complexes formed between each enantiomer and the chiral framework of the stationary phase. This difference in energy is related to a which is experimentally obtained by the ratio of the capacity factors of the two enantiomers: k12/k'l. The larger is a, the better is the chiral discrimination between the two enantiomers by the chiral support or in other term the better is the molecular recognition of one enantiomer by the chiral selector. The enantiomer having the smallest affinity with the support will be eluted first.