反应详情

To a solution of (2-nitrophenyl)-terephthalamic acid methyl ester (0.23 g, 0.76 mmol) in glacial acetic acid (2.5 mL) was added iron powder (<5 μm mesh, 0.12 g, 2.1 mmol) and the mixture stirred at reflux for 1 h. The mixture was cooled, stirred at room temperature for 2 h and concentrated under reduced pressure. The residue was partitioned between saturated sodium bicarbonate (10 mL) and ethyl acetate (10 mL), the phases separated and the organic layer washed with saturated NaHCO3 (10 mL). The organic extract was dried (MgSO4), filtered and concentrated to give cyclized methyl 4-(benzimidazol-2-yl)-benzoate (0.163 g, 86%). 1H NMR (CDCl3) δ 3.96 (s, 3H), 7.32 (m, 2H), 7.53 (br, 1H), 7.84 (br, 1H), 8.17 (m, 4H), 9.65 (br, 1H (NH)).

1. temperatureat reflux for 1 h
2. temperatureThe mixture was cooled
3. stirringstirred at room temperature for 2 h
4. concentrationconcentrated under reduced pressure
5. customThe residue was partitioned between saturated sodium bicarbonate (10 mL) and ethyl acetate (10 mL)
6. customthe phases separated
7. washthe organic layer washed with saturated NaHCO3 (10 mL)
8. extractionThe organic extract
9. dry with materialwas dried (MgSO4)
10. filtrationfiltered
11. concentrationconcentrated