反应详情

温度

110 °C

A mixture of 3,4-diaminobenzoic acid (9.4 g, 62 mmol), ethyl 3-ethoxy-3-iminopropionate and glacial acetic acid (15 mL) was stirred 30 minutes at 110° C. under nitrogen. The mixture was poured over crushed ice (50 mL) and stirred 30 minutes to give a dark yellow oil. The mixture was stirred while diethyl ether (25 mL) was added to give a gray precipitate. The precipitate was isolated by filtration, washed several times with diethyl ether and dried under vacuum to provide 2-ethoxycarbonylmethyl-1H-benzoimidazole-5-carboxylic acid (12.6 g, 83% yield); 1H-NMR (300 Mhz, DMSO-d6): 12.77 (broad s, 1H), 8.10 (s, 1H), 7.79 (d, 1H, J=8.4 Hz), 7.57 (d, 1H, J=8.4 Hz), 4.11 (q, 2H, J=7.1 Hz), 4.02 (s, 2H), 1.17 (t, 3H, J=7.1 Hz).

1. additionThe mixture was poured
2. stirringstirred 30 minutes
3. customto give a dark yellow oil
4. additionwas added
5. customto give a gray precipitate
6. customThe precipitate was isolated by filtration
7. washwashed several times with diethyl ether
8. customdried under vacuum