反应详情

A mixture of 3-(Formylamino)-4-methyl-2-nitrobenzoic acid (18) and 3-(Formylamino)-4-methyl-6-nitrobenzoic acid (18b) in a ratio of about 66:34 (9.999 g, 44.56 mmol) and Pd/C (10%, 2 g, 4 mol % Pd) in 75% aqueous formic acid (120 mL, 0.5M) is heated at reflux for about 15 hours. The reaction mixture is then cooled to ambient temperature and filtered through a pad of Celite, and the filtrate is concentrated in vacuo to 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 (5.564 g, 98% Yield, based on amount of 3-(Formylamino)-4-methyl-2-nitrobenzoic acid (18) in the starting material mixture).

1. temperatureis heated
2. temperatureat reflux for about 15 hours
3. filtrationfiltered through a pad of Celite
4. concentrationthe filtrate is concentrated in vacuo to a beige solid
5. customThe solids are triturated in hot methanol (50 mL)
6. temperaturecooled slowly to ambient temperature
7. filtrationfiltered