反应详情

A mixture of 3-(Formylamino)-6-bromo-4-methyl-2-nitrobenzoic Acid (21) (1.055 g, 3.68 mmol) and palladium on carbon (10% Pd/C, 0.228 g) in aqueous NaOH (0.294 g, 7.35 mmol of solid NaOH in 100 mL of H2O) is hydrogenated under hydrogen pressure (40 psi) for about 16 hours. The reaction mixture is cooled to ambient temperature and filtered through a pad of Celite. The filtrate is acidified with HCO2H (about 25 mL) and heated to reflux for about 2 hours. The reaction mixture is cooled and concentrated in vacuo to give a beige solid. The solids are triturated in hot methanol (50 mL), cooled slowly to ambient temperature, and filtered to give 7-Methyl-1H-benzimidazole-4-carboxylic Acid (22), as beige solid (0.495 g, 81% yield).

1. customfor about 16 hours
2. filtrationfiltered through a pad of Celite
3. temperatureheated
4. temperatureto reflux for about 2 hours
5. temperatureThe reaction mixture is cooled
6. concentrationconcentrated in vacuo
7. customto give a beige solid
8. customThe solids are triturated in hot methanol (50 mL)
9. temperaturecooled slowly to ambient temperature
10. filtrationfiltered