反应详情

温度

70 °C

Methyl 3,4-diamino-2-methylbenzoate (synthesized in reagent preparation 22) (0.18 g, 1.0 mmol) was taken up in formic acid (8.0 mL) and refluxed for 4 hours. The solution was then concentrated in vacuo. The material was taken up in methanol (2.5 mL) and tetrahydrofuran (5.0 mL) and treated with 2M aqueous lithium hydroxide (2.5 mL) and heated to 70° C. for 12 hours. This solution was made acidic using concentrated aqueous hydrochloric acid, then extracted with 10% methanol in ethyl acetate (2×50 mL). The combined organic layers were dried (magnesium sulfate), filtered and concentrated to give 0.055 g of 7-methyl-1H-benzimidazole-6-carboxylic acid. 1H NMR (400 MHz, d6-DMSO): 9.34 (s, 1H), 7.94 (d, 1H), 7.64 (d, 1H), 2.85 (s, 3H). MS (EI) for C9H8N2O2: 177 (MH+).

1. temperaturerefluxed for 4 hours
2. concentrationThe solution was then concentrated in vacuo
3. additiontetrahydrofuran (5.0 mL) and treated with 2M aqueous lithium hydroxide (2.5 mL)
4. extractionextracted with 10% methanol in ethyl acetate (2×50 mL)
5. dry with materialThe combined organic layers were dried (magnesium sulfate)
6. filtrationfiltered
7. concentrationconcentrated