Patent ID: 7531666

Claim:
A method for preparing 2-(2-pyridinylmethylsulfinyl)benzimidazole having the following formula [A], which comprises undergoing an oxidation reaction of an intermediate having the following formula [B] in a solvent and in the presence of a catalyst, an oxidant and a base to form the compound [A]: wherein R 1 in [A] and [B] is hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkyl, or halogenated C1-C6 alkoxy; R 2 and R 3 independently are hydrogen, halogen, C1-C6 alkyl, C1-C6 alkoxy, halogenated C1-C6 alkyl, or halogenated C1-C6 alkoxy; and R 4 is hydrogen, halogen, C1-C6 alkyl, halogenated C1-C6 alkyl, C1-C6 alkoxy, or halogenated C1-C6 alkoxy; wherein the improvement comprises said catalyst comprises an alkali metal salt of tungstate; and said oxidation reaction is carried out at a temperature of 10-50° C.