Patent ID: 6919459

Claim:
An process for preparing benzimidazole-type compounds of general formula (I) wherein R 1 and R 2 are the same as or different from each other and are selected from hydrogen, methoxy or difluoromethoxy, R 3 , R 4 and R 5 are the same as or different from each other and are selected from hydrogen, methyl, methoxy, methoxypropoxy or trifluoroethoxy, characterized by the steps of a) reacting a compound of general formula (II) with an oxidizing agent in a suitable solvent, b) extracting the reaction mixture with an aqueous alkaline solution with a pH ranging from 9.50 to 12.00 and removing the water layer, c) extracting the organic layer of the previous step with an aqueous alkaline solution having a pH of 13.0 or higher and removing the organic layer, d) isolating the compound of formula (I) from the water layer of the previous step.