Chirality最新文献

We have recently celebrated the 150th anniversary of the tetrahedral carbon (1874–2024), as postulated by van't Hoff and Le Bel, who published their seminal breakthrough only 2-months apart, on September 5 and November 5, 1874, respectively. The concept is a fundamental pillar of structural chemistry and, if we may say so, of molecular sciences. How two young men in their early careers dared to disturb the established way of thinking constitutes the jumping-off of scientific theories as constructive elements, rather than arguments derived from experiments. Chirality makes no sense without geometry. Nor can we interpret a molecular scenario devoid of spatial considerations. All in all, a felicitous celebration to be highlighted.

2-Thiohydantoin derivatives, including different substitutions at N-1 and C-5 (5-methyl-, 5-isopropyl-, 1-acetyl-5-methyl-, and 1-acetyl-5-isopropyl-) (1–4, respectively), were synthesized by the known literature methods. In these synthetic pathways, it was reported that enantiomerically pure 2-thiohydantions were obtained in the absence of any solvent via the reaction of L-amino acids with thiourea (1&2) and via the reaction of L-amino acids with NH₄SCN and acetic anhydride (3&4). However, in this study, in contrary to the previous literature studies, racemic mixtures of 2-thiohydantoins were obtained although the same synthetic methods were used. The racemic nature of 2-thiohydantoin derivatives (1–4) was proved by using ¹H NMR analysis in the presence of (1R,2S)-(−)-ephedrine as a chiral auxiliary. In addition, the enantiomers of 3&4 were also resolved on chiral stationary phases by HPLC analyses. Furthermore, newly synthesized unsymmetrical chiral thioureas (S-1&S-2) and previously synthesized symmetrical ones (SS-3&SS-4) were used as chiral solvating agent (CSA) for the enantiodiscrimination of the thiohydantoins (5&6), previously reported. Optimal CSA/substrate ratios were determined for the best enantiodiscrimination.

Chirality plays a crucial role in the pharmacological activity of triazoles, a key scaffold in antifungal agents and various therapeutic applications. This study focuses on optimizing the enantiomeric resolution of chiral triazoles using supercritical fluid chromatography (SFC) and 10 different columns, either immobilized or coated, chlorinated or nonchlorinated, cellulose or amylose-based chiral stationary phases (CSPs). Four novel triazoles and two marketed ones (tebuconazole and hexaconazole) were separated to determine optimal resolution conditions. The best resolution was achieved using chlorinated amylose-based CSPs across the tested compounds. Optical rotation and X-ray crystallography were employed to determine the absolute configurations of the purified enantiomers.

The synthesis, structure, and circularly polarized luminescence (CPL) properties of axially chiral boron difluoride complexes are described. A series of optically pure bis (boron difluoride) complexes were prepared in 5 steps from commercially available (S)- or (R)-BINOL as starting materials. The complexes were found to exhibit similar yellow photoluminescence in solution, regardless of the type of substituents on the nitrogen atoms. Notably, for the complex with polyethylene glycol chains, homogeneous and transparent films were formed by the drop-cast method, showing intense CPL with a different sign from that of the solution state. Density functional theory (DFT) calculations were performed to understand their photophysical behavior including configuration-dependent CPL properties.

A vibrational circular dichroism (VCD) instrument having a thermoelectrically cooled detector (denoted as a TEC unit) was constructed in this study. An electronic device, instead of liquid nitrogen, was employed in the instrument to cool the detector. The feasibility of the system was examined by recording the VCD spectra of liquid pinenes and insect wings. VCD signals were obtained at a constant baseline that was stable for more than 40 h. The spectrometer equipped with a TEC unit exhibited potential for performing measurements for prolonged time periods.

Chiral pesticides often undergo enantioselective degradation during food fermentation. In this study, the enantioselective fates of seven chiral pesticides during processing of wine and rice wine were investigated. The results revealed that R-metalaxyl, R-mefentrifluconazole and S-hexaconazole were preferentially degraded during wine processing with EF values of 0.57, 0.78, and 0.43, respectively, whereas S-metalaxyl and R-hexaconazole were preferentially degraded during rice wine processing with EF values of 0.44 and 0.54, respectively. Stereoselectivity was attributed to fermentative bacterial activity. The processing factor (PF) values for the five pesticides ranged from 0.04 to 0.34 during wine processing and from 0.02 to 0.29 during rice wine processing, suggesting that fermentation can mitigate pesticide exposure risks and ensure food safety. This study enhances our understanding of enantioselective fate of chiral pesticides during fermented food processing, provides guidance for the application of chiral pesticides, and enables the dietary risk of chiral pesticides in processed products to be assessed more accurately.

Efficient enantioselective separation is a critical process in pharmaceutical and chemical industries for the production of chiral compounds. Herein, we developed a novel approach for the efficient enantioselective separation of primary amines using supercritical fluid chromatography (SFC) with a commercially available SFC column, Cel1. The key factors of separation, including cosolvent ratios, total cosolvent percentages, and temperature, were systematically assessed in this study. It revealed that utilization of a cosolvent mixture consisting of methanol and isopropanol in a 1:3 (v/v) ratio with a low total cosolvent percentage of 5% resulted in superior retention and selectivity. Additionally, it was observed that maintaining mid-range temperatures at 30 and 35°C achieved optimal balance between retention and efficiency. Employment of commercially available SFC columns streamlined the separation process, reducing analysis time and labor. This study highlights the effectiveness of SFC as a powerful tool for conducting high-throughput enantioselective separations in pharmaceutical and fine chemical industries.

Enantiomeric analysis of chiral drugs is very significant, as their enantiomers display different pharmacological or toxicological behavior towards living systems. Among these drugs, β-blockers are available as racemates, where their enantiomers display different pharmacological effects. Herein, we report enantioselective separation of two β-blockers, namely, atenolol and sotalol, using a derivatization approach. The analytes were derivatized with “(S)-1-[1H-benzo(d)(1,2,3)triazol-1-yl]-2-[6-methoxynaphthalen-2-yl-propan-1-one]” {(S)-BTMNP} in a straightforward derivatization step. The resulting diastereomers were separated on a reverse-phase HPLC C18 column with a mobile phase composed of acetonitrile and TEAP buffer (75:25, v/v, pH = 3.5) and detection at 230 nm. This method achieved successful enantiomer separation for both drugs within 20 min, yielding resolution values greater than 3.8. The detection limits were determined to be 6.4 and 4.6 ng mL⁻¹ for atenolol and sotalol, respectively, which indicated sensitivity and effectiveness of the method for the analysis of two β-blockers from their dosage formulations.