A mixture of 2-mercaptobenzimidazole-5-carboxylic acid (3.25 g), 3-(4-acetyl-3-hydroxy-2-propylphenoxy)propylbromide (2.00 g) and potassium hydroxide (1.27 g) in ethanol (30 ml) was refluxed for 4 hours. Then, the reacting mixture was poured into ice-water, made acidic with concentrated hydrochloric acid and extracted with ethyl acetate. The organic layer was dried over anhydrous sodium sulfate and then evaporated. The resulting residue was purified by silica gel column chromatography, eluting with dichloromethane-ethyl acetate-methanol (10:2:1), and recrystallized from n-hexane-ethyl acetate to give the title compounds (3.00 g, 67.1%) as pale yellow crystals, mp 106-108 ° C.
