反应详情

10% sodium hydroxide aqueous solution (3.10 g) and ethanol (10 ml) are added to 1-(2,4-dichlorobenzyl)-6-ethoxycarbonyl-2-methylbenzimidazole (0.94 g) (example 70), and the solution is refluxed by heating for 1 hour. Its acidity is adjusted to pH 6 with 10% hydrochloric acid. The precipitated crystals are separated through filtration, dried, and thus, 6-carboxy-1-(2,4-dichlorobenzyl)-2-methylbenzimidazole (0.68 g) is obtained. 1H-NMR (DMSO-d6, δ): 2.52 (3H, s), 5.61 (2H, s), 6.54 (1H, d, J=8.4 Hz), 7.33 (1H, dd, J=8.4 and 2.1 Hz), 7.64 (1H, d, J=8.4 Hz), 7.74 (1H, d, J=2.1 Hz), 7.81 (1H, dd, J=8.4 and 1.5 Hz), 7.98 (1H, s), 12.72 (1H, s).

1. temperaturethe solution is refluxed
2. temperatureby heating for 1 hour
3. customThe precipitated crystals are separated through filtration
4. customdried