Lansoprazole → Dexlansoprazole

Participants

Reaction Steps

2-[[[3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridinyl]methyl]sulfinyl]-1H-benzimidazole (lansoprazole) (racemate) (3.98 g) was dissolved in the following mobile phase (330 ml) and acetonitrile (37 ml) and fractionated by HPLC (column: CHIRALCEL OD 20 mm dia.×250 mm, temperature: 30° C., mobile phase: hexane/2-propanol/ethanol=255/35/10, flow rate: 16 ml/min, detection wavelength: 285 nm, 1 shot: 20-25 mg). Fractions of optical isomers of shorter retention time were combined and concentrated; the individual lots were combined and dissolved in ethanol and filtered through a 0.45 μm filter; after hexane was added, the filtrate was again evaporated to dryness to yield R(+)-lansoprazole (1.6 g, optical purity >97.6% ee) as an amorphous substance.

Provenance & Evidence