Enantioselective HPLC separation of bioactive C5-chiral 2-pyrazolines on lux amylose-2 and lux cellulose-2: Comparative and mechanistic approaches

Enantioselective Separation of Chiral N1-Substituted-1H-pyrazoles: Greenness Profile Assessment and Chiral Recognition Analysis

Two commercialized polysaccharide-based chiral stationary phases, Lux cellulose-2 and Lux amylose-2, were examined for their chiral recognition ability on a set of 18 biologically active racemic 4,5-dihydro-1H-pyrazole derivatives by applying normal and polar organic elution modes. The results showed that all compounds were baseline-resolved with at least one of the used elution modes. The cellulose-based column was superior using polar organic mobile-phase compositions with analysis times close to 5 min and resolutions up to 18, while the enantiomer-resolving ability of amylose-based columns was greater using the normal elution mode with analysis times close to 30 min and resolutions up to 30. The competition between the analytes and the mobile phase constituents on H-bond interactions with the stationary phase has been discussed, and the impact of this competition on chiral recognition has been investigated. It was found that the polar organic mode is very beneficial for short run times and sharp peaks. The developed enantioselective high-performance liquid chromatography (HPLC) methods will be applied to monitor the stereoselective synthesis of compounds 1-18 or to develop preparative HPLC techniques for compounds 1-18, followed by stereospecific pharmacological studies for each enantiomer separately. Greenness profile assessment of the different elution solvents was carried out using the AGREE metric approach.

Enantioselective Chromatographic Separation and Lipase Catalyzed Asymmetric Resolution of Biologically Important Chiral Amines

Cyanoacetamides are vital synthons in synthetic organic chemistry. However, methods to enantiopure cyanoacetamides have not yet been well explored. In this work, the preparation of cyanoacetamide synthons RS-(1a–4a) or methoxyacetamides RS-(1b–4b) in enantiopure/enriched form was investigated. Compounds S-1, S-2, R-1b, R-1a, andR-2b were prepared in enantiopure form (ee > 99%) while compounds S-4, R-2a, and R-4a were achieved in ee 9%, 80%, and 76%, respectively. Many baselines enantioselective HPLC separations of amines 1–4, their cyanoacetamides (1a–4a), and methoxyacetamides (1b–4b) were achieved by utilizing diverse mobile-phase compositions and two cellulose-based CSPs (ODH® and LUX-3® columns). Such enantioselective HPLC separations were used to monitor the lipase-catalyzed kinetic resolution of amines RS-(1–4).

Chirobiotic V Versus Chiralpak ID for the Enantioselective Chromatographic Separation of Chloroquine: Stability and Validation Study

Chloroquine is a chiral antimalarial drug and demonstrates enantioselective pharmacodynamic and pharmacokinetic properties. However, this drug is administered as racemate. The knowledge of stereoselective aspects of these agents may be useful to better understand their mechanisms of action and to optimize their safety and/or clinical efficacy. In this study, an enantioselective analytical method for the quantification of chloroquine enantiomers was developed using HPLC-UV. The chromatographic conditions were: Chirobiotic V column (100 × 2.1 mm, 5 μm) at 25°C, mobile phase containing methanol:acetic acid:triethylamine (100:0.12:0.12), flow rate 1 mL/min, injection volume 10 μL and detection at 258 nm. The validation parameters evaluated were selectivity, linearity, precision, accuracy, and robustness. In addition, a stability study after forced degradation of chloroquine enantiomers was performed. The enantioseparation of chloroquine using a polysaccharide-based chiral stationary phase (Chiralpak ID) at different mobile phase composition was evaluated and the chromatographic performance of both columns was compared. Thus, a stability-indicating chiral analytical method was developed and fully validated, allowing the separation of chloroquine enantiomers and its degradation products in tablets available in Brazil.

One-step lipase-catalysed preparation of eslicarbazepine

The antiepileptic eslicarbazepine (S-licarbazepine) has been prepared in one step from its racemic formRS-licarbazepinevialipase catalysed kinetic resolution.