Mining Chromatographic Enantioseparation Data Using Matched Molecular Pair Analysis.

We apply matched molecular pair (MMP) analysis to data from ChirBase, which contains literature reports of chromatographic enantioseparations. For the 19 chiral stationary phases we examined, we were able to identify 289 sets of pairs where there is a statistically significant and consistent difference in enantioseparation due to a small chemical change. In many cases these changes highlight enantioselectivity differences between pairs or small families of closely related molecules that have for many years been used to probe the mechanisms of chromatographic chiral recognition; for example, the comparison of N-H vs.

Strong enantioselective self-recognition of a small chiral molecule.

In the present report, we have crystallized a single enantiomer and the racemate of N-3,5-dinitrobenzoyl (DNB) leucine. In both cases, the X-ray structures show clear evidence of homochiral dimerization in the solid state. Moreover, only homochiral dimers were observed in the unit cell of the racemate, a result of solid-state enantioselective complexation.

Formation of stable Meisenheimer adduct ion pairs in apolar solvents: implications for stereoselective reactions.

[reaction: see text] A detailed study concerning the formation of Meisenheimer adducts in biphasic solvent systems is described. The process relies on utilizing a significantly lipophilic quaternary ammonium salt to transfer a nucleophile (e.g.

The effects of aromatic substituents on the chromatographic enantioseparation of diarylmethyl esters with the whelk-O1 chiral stationary phase.

Members of a series of diarylmethanols, diarylmethyl pivalates, and diarylmethyl acetates (analyte sets 1-26) were enantioresolved with the (S,S)-Whelk-O1 chiral stationary phase (CSP). An analogue of the (S,S)-Whelk-O1 selector was combined with enantioenriched samples of the various diarylmethyl pivalates and thereby used as a chiral solvating agent (CSA) for high field 1H NMR studies. The absolute configurations of a number of chiral diarylmethyl pivalates were assigned using this approach, and hydrolysis of the pivalates allowed assignment of the absolute configurations of the corresponding diarylmethanols.