The present invention is directed to a process for the catalytic oxidation of the thioether 5-methoxy-2-((4-methoxy-3,5-dimethyl-2-pyridinyl)methyl)methylthio)-1H-benzimidazole to its sulfoxide: 5-methoxy-2-((4-methoxy-3,5-dimethyl-2-pyridinyl) methyl)methylsulfinyl)-1H-benzimidazole comprising: reacting the thioether with: 1) a transition metal catalyst; and, 2) an oxygen source; wherein the thioether is oxidized to a sulfoxide and wherein one of either the R and S enantiomers is formed to an enantiomeric excess.
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