A novel thermoregulated phase-transfer catalysis system for chiral nano-Pt-catalyzed asymmetric hydrogenation

The chiral ionic liquid CILTPT-MS [CH3(OCH2CH2)16CD]+[CH3SO3]− (CD = cinchonidine) is found to exhibit cloud point character. Due to this cloud point character, a CILTPT-MS-stabilized chiral nano-Pt catalyst is prepared and utilized to realize transfer in a H2O–1-pentanol biphasic system by simply changing the temperature. Therefore, a fluorine-free, thermoregulated phase-transfer catalysis system is developed and applied to the asymmetric hydrogenation of α-ketoesters with enantiomeric excess of >99% and excellent conversion. In addition, the chiral nano-Pt catalyst can be easily separated and reused efficiently.

L-Histidinium Chiral Ionic Liquid Functionalized β-Cyclodextrin as Chiral Selector in Capillary Electrophoresis

Nowadays, ionic liquids (ILs) functionalized cyclodextrins (CDs) have drawn increasing attention in chiral separation. Herein, a novel β-CD derivative functionalized by L-histidinium IL, mono-6-deoxy-6-L-histidinium-β-cyclodextrin chloride (L-HMCDCl), was synthesized for the first time and utilized for enantioseparation of nefopam and chlorphenamine in capillary electrophoresis. The L-HMCDCl exhibited superior enantioselectivity compared with native β-CD. The effect of some key parameters such as chiral selector concentration, buffer pH and applied voltage on the enantioseparation was investigated in detail. In the interest of the chiral discrimination mechanism and the enhanced enantioselectivity of L-HMCDCl, molecular modeling with AutoDock was employed to study the interaction, which was in good agreement with experimental results.

Efficient Construction of 4-hydroxy-4-arylbutan-2-ones through an Enantioselective Aldol Reaction Mediated by a Recoverable Proline-Based Chiral Ionic Liquid

Chiral ionic liquid derived from L-proline worked as an excellent organocatalyst for the enantioselective aldol reaction of aromatic aldehydes and acetone. The reaction was conducted in the presence of [BMIM][BF4] as reaction medium. The substrate scope of aldol reaction was successfully explored for various aromatic aldehydes under the mild conditions. The generated aldol products were separated by column chromatography with moderate to good yields as well as enantioselectivities. The main advantage of this catalytic method was that the catalyst and solvent could be recovered at the same time and reused for at least five times with satisfactory performance.