反应详情

A mixture of 3-nitro-4-phenylacetylamino-ethylbenzoate (3.60 g), ethanol (47 ml), acetic acid (23 ml) and reduced iron (6.4 g) is refluxed for four hours. Solids are separated through filtration and the filtrate is concentrated. Ethanol (50 ml) and 35% hydrochloric acid (5 g) are added to the residue and the solution is refluxed for 40 hours. The solution is neutralized with sodium bicarbonate and chloroform extraction is performed. The organic layer is concentrated under reduced pressure and then purified using silica gel column chromatography. Thus, 2-benzyl-5-ethoxycarbonylbenzimidazole (2.30 g) is obtained. 1H-NMR (CDCl3, δ): 1.39 (3H, t, J=7.1 Hz), 4.26 (2H, s), 4.37 (2H, q, J=7.1 Hz), 7.22-7.36 (5H, m), 7.50 (1H, d, J=8.6 Hz), 7.94 (1H, dd, J=1.5 and 8.6 Hz), 8.23 (1H, d, J=1.3 Hz).

1. temperatureis refluxed for four hours
2. customSolids are separated through filtration
3. concentrationthe filtrate is concentrated
4. additionEthanol (50 ml) and 35% hydrochloric acid (5 g) are added to the residue
5. temperaturethe solution is refluxed for 40 hours
6. extractionThe solution is neutralized with sodium bicarbonate and chloroform extraction
7. concentrationThe organic layer is concentrated under reduced pressure
8. custompurified