Hexylitaconic acid (1) is an intriguing natural product possessing a chiral carbon, and both its enantiomers have been found in nature. Enantiomeric pure (+)-(1) and (-)-(1) were successfully prepared by racemic synthesis followed by enantiomeric separation in a chiral HPLC system. Their absolute configurations were clarified by the vibrational circular dichroism technique using their methyl es...

We present an optical "enantio-selective switch" that, in two steps, turns a ("racemic") mixture of left-handed and right-handed chiral molecules into the enantiomerically pure state of interest. The optical switch is composed of an "enantio-discriminator" and an "enantio-converter" acting in tandem. The method is robust, insensitive to decay processes, and does not require molecular preorienta...

Chirality plays an important role in the formation and stability of noncovalent clusters which are made of chiral molecules. It is shown that clusters can exhibit a preference for both homochirality and heterochirality. Serine cluster formation is dominated by the formation of heterochiral aggregates, with the exception of the previously observed homochiral serine octamer. Thus, the majority of...

The helix is a critical conformation exhibited by biological macromolecules and plays a key role in fundamental biological processes. Biological helical polymers exist in a single helical sense arising from the chiral effect of their primary units-for example, DNA and proteins adopt predominantly a right-handed helix conformation in response to the asymmetric conformational propensity of D-suga...

Carvedilol is administered as a racemic mixture of the R(+)- and S(-)-enantiomers, although it was demonstrated that the two enantiomers exhibit different pharmacological effects and stereoselective pharmacokinetics. The aim of this study was the evaluation of several native and derivatized cyclodextrines as chiral selectors for the separation of carvedilol enantiomers. Stereoselective interact...

Chiral derivatives of γ-aminobutyric acid are widely used as medicines and can be obtained by organocatalytic Michael additions. We show here the stereoselective synthesis of 4-methylpregabalin stereoisomers using a Michael addition of dimethyl malonate to a racemic nitroalkene. The key step of the synthesis operates as a kinetic resolution with a chiral squaramide catalyst. Furthermore, specif...

In this paper we examine theoretically the chiral discrimination of molecules with a single chiral center. We propose a definition of the chiral discrimination parameter A in terms of the difference between the second virial coefficient of pure enantiomers and their racemic mixture. This parameter enters in the equation of state of racemic mixtures and will determine their phase diagrams. We ca...

We report a protocol for the highly efficient iridium-catalyzed asymmetric hydrogenation of racemic a-substituted lactones via dynamic kinetic resolution. Using Ir-SpiroPAP (R)-1d as a catalyst, a wide range of chiral diols were prepared in a high yield (80–95%) with a high enantioselectivity (up to 95% ee) under mild reaction conditions. This protocol was used for enantioselective syntheses of...

We report a protocol for the highly efficient iridium-catalyzed asymmetric hydrogenation of racemic α-substituted lactones via dynamic kinetic resolution. Using Ir-SpiroPAP (R)-1d as a catalyst, a wide range of chiral diols were prepared in a high yield (80-95%) with a high enantioselectivity (up to 95% ee) under mild reaction conditions. This protocol was used for enantioselective syntheses of...

Cooxidation activity of highly purified soybean lipoxygenase-2 and -3 was investigated with all-trans-retinoic acid as a co-substrate. Both the isoenzymes rapidly degraded retinoic acid in the presence of linoleic acid, but lipoxygenase-2 had more cooxidation activity than lipoxygenase-3. During cooxidation, 5, 6-epoxyretinoic acid was formed as a major product. HPLC on a chiral phase (Ceramosp...