Patent ID: 7507746

Claim:
A method for the preparation of (−)-tenatoprazole, or (−)-5-methoxy-2-{[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]sulfinyl}imidazo-[4,5-b]pyridine, or one of its salts, wherein the compound has at least 98.8% chiral purity, comprising performing column chromatography on a racemic mixture of (+) and (−)-tenatoprazole to provide (−)-tenatoprazole, or (−)-5-methoxy-2-{[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]sulfinyl}imidazo-[4,5-b]pyridine, or one of its salts, that has at least 98.8% chiral purity.