反应详情

2-(4-fluoro-phenyl)-7-hydroxy-1H-benzoimidazole-4-carboxylic acid (500 mg, 1.84 mmol) obtained in step 3 was dissolved in methanol, H2SO4 (0.49 ml, 9.20 mmol) was added dropwise thereto and refluxed for 15 hours. The resulting solution was cooled to room temperature, concentrated under a reduced pressure to remove methanol, and the residue was neutralized with NaHCO3. Then, the neutralized residue was extracted with ethyl acetate and concentrated under a reduced pressure to obtain a residue which was purified by silica gel chromatography to obtain the title compound (397 mg, 1.39 mmol) in a yield of 76%.

1. temperaturerefluxed for 15 hours
2. concentrationconcentrated under a reduced pressure
3. customto remove methanol
4. extractionThen, the neutralized residue was extracted with ethyl acetate
5. concentrationconcentrated under a reduced pressure
6. customto obtain a residue which
7. customwas purified by silica gel chromatography