5-(1H-Pyrrol-1-yl)-1H-benzo[d]imidazole-2-thiol

5-(1H-Pyrrol-1-yl)-2-mercaptobenzimidazole is a pharmaceutical intermediate compound used in the synthesis of various drugs such as ilaprazole, gastric and ulcer drugs.

Water (100ml) and anhydrous sodium acetate (16.02g, 0.20mole) were added, and then 2-mercapto-5- aminobenzimidazole (32.27g, 0.20mole),2,5-dimethoxytetrahydrofuran (28.4g, 0.21mole), and acetic acid (100ml) were added. Then, stirring was carried out at 5O℃ for 4 hours. The resultant product was cooled to 50C, and tetrahydrofuran (420ml) was added. The mixture was neutralized with a sodium hydroxide aqueous solution, and water (130ml) was added to carry out layer- separation. Then, an organic layer was washed with a sodium hydroxide aqueous solution. The organic layer was dried by anhydrous magnesium sulfate and concentrated, and then crystallized by ethyl acetate and n-hexane to provide a final compound, that is 5-(1H-Pyrrol-1-yl)-1H-benzo[d]imidazole-2-thiol. Yield: 35.7g (85%)