Chirality chromatographic separations

Most chiral chromatographic separations are accompHshed using chromatographic stationary phases that incorporate a chiral selector. The chiral separation mechanisms are generally thought to involve the formation of transient diastereomeric complexes between the enantiomers and the stationary phase chiral ligand. Differences in the stabiHties of these complexes account for the differences in the retention observed for the two enantiomers. Often, the use of a... 

A. M. Dyas, The chiral chromatographic separation of /3-adrenoceptor blocking drugs, J. Pharm Biomed. Anal., 10 383 (1992). 

Acetalization of thiochroman-3-one gives a 1 1 diastereomeric mixture and subsequent oxidation with Davis reagent, W-(phenylsulfonyl)(3,3-dichlorocamphoryl)oxaziridine, yielded the sulfoxides each with a 4 1 enantioselectivity. Chiral chromatographic separation of the diastereomers preceded isolation of the major enantiomers. (3-Elimination and isomerization of the double bond then produced the individual thiochromene 1-oxide diastereomers. The generation of an a-sulfinyl carbanion effects the cleavage of one of the acetal C-O bonds with the protected diol released in a final ozonolysis step. The stereochemical results indicate that it is the C-O bond syn to the sulfoxide function that is cleaved (Scheme 63) <1996TA29>. 

S)-citalopram The MIP coated stir-bars for chiral chromatographic separation Gomez- Caballero etal.2011... 

Kurganov A (2001) Chiral chromatographic separations based on ligand exchange. Journal of Chromatography A 906 51-71. 

T, D. Booth, K. Azzaoui, and I. W. Wainer, Anal. Chem., 69, 3879 (1997). Prediction of Chiral Chromatographic Separations Using Combined Multivariate Regression and Neural Networks. 

At this point, efforts were made to determine which methyl stereoisomer preferably bound to the c-Met protein. Chiral chromatographic separation of the racemic compound 5 and biological assessment of the resulting enantiomers demonstrated that... 

A variant of the above technique is to use a mobile phase that Itself Is chiral. This leads to the formation of a transient diastereolsomeric complex between the enantiomers md the chiral mobile phase agent. Chiral mobile phase agents that hve given good results are 10-camphorsulphonic acid, albumin, and N-benzojqrcarbonyglycyl-L-proline. It is usueil to prefer reversed phase chromatography for chiral chromatographic separations. 

Chiral chromatographic separation techniques such as GC, HPLC, and CE provide the real separation of enantiomers. By real, one means that the two enantiomers of the racemates can actually be separated and obtained in individual containers. Particularly for chiral preparative HPLC, both the optically pure enantiomers can be obtained after the chiral chromatographic separation. However, in spectroscopic techniques, there is no real separation of enantiomers. Nonetheless, chiral spectroscopic techniques are still very important and useful resources for chiral technology in that they can rapidly and accurately determine the enantiopurity of chiral compounds. In addition, they can offer important information regarding the structure-property relationship and differentiation mechanism during chiral interaction and recognition. Recently, CILs have been used as the chiral selectors in spectroscopic techniques such as nuclear magnetic resonance (NMR), fluorescence, and near infrared (NIR). 

In this chapter, the application of CILs in various fields has been discussed. This is with particular focus on the chiral chromatographic separations and spectroscopic discrimination. Chiral recognition and separation mechanism using CILs so far have not been thoroughly studied. This chapter discusses the enantiomeric discrimination mechanism using CILs as chiral selectors from some preliminary results. 

The main disadvantage of a chiral chromatographic separation is that the chiral silica gel is much more expensive than a standard silica gel. 

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