| abstract |
The present invention relates to a process for preparing lansoprazole of the following formula (I) and its intermediate, 2-[3-methyl-4(2,2,2-trifluoroethoxy)-2-pyridil]methylthio-1H-benzimidazole of the following formula (II), which comprises reacting 2-hydroxymethyl-3-methyl-4-(2,2,2-trifluoroethoxy) pyridine or its salt with 2-mercaptobenzimidazole in the presence of a halogenating agent and reaction solvent, and then oxidizing the resulting compound (II) with hydrogen peroxide in the presence of a benzeneseleninic acid catalyst and reaction solution to obtain lansoprazole(I). |