Enantiomeric Separation of (R)-5-(1-Hydroxyethyl)-2-(pyridine- 2-yl)-[1, 3, 4]-thiadiazole, an Intermediate of Nafithromycin on Immobilized Amylose Based Stationary Phase

Abstract Chiral high performance liquid chromatography method for the separation of (R)-5-(1- Hydroxyethyl)-2-(pyridine-2-yl)-[1, 3, 4]-thiadiazole (R-alcohol) an intermediate of new antibiotic Nafithromycin (NFT) has been developed and validated. NFT is a ketolide class of antibiotic currently under Phase III clinical trials in India to treat community acquired bacterial pneumonia. Chiral separation of the enantiomers with resolution >2 was accomplished on Chiralpak IA column using a mixture of n-hexane and isopropanol (IPA) in the ratio of (90:10; v/v) as an elution solvent, run at a flow rate of 1.2 mL.min-1. The column was maintained at 25°C. The analytes were detected at 254 nm. The developed method was extensively validated as per the international council for harmonisation of technical requirements for pharmaceuticals for human use guideline. Sensitivity of the method was adequate to control the passage of unwanted enantiomer to next step with limit of quantification (LOQ) of the undesired enantiomer (S)-5-(1-Hydroxyethyl)-2-(pyridine- 2-yl)-[1, 3, 4]-thiadiazole (S-alcohol) of 0.37 µgmL-1. Mean recovery of the S-alcohol was 98.9±8.7%. During development influence of column oven temperature on the chiral separation was assessed. GRAPHICAL ABSTRACT