反应详情

To a solution of 1,2-dimethyl-4-methoxy-1H-benzimidazole (560 mg) in dichloromethane (2 ml) was added 1M boron tribromide-dichloromethane solution (6.36 ml) under ice-cooling, and the mixture was stirred for 30 minutes at the same temperature and then for 2 hours at ambient temperature, and refluxed for 14 hours. After cooling, the solution was adjusted to pH 7 with saturated sodium bicarbonate solution, and extracted with dichloromethane twice. The organic layers were combined, washed with brine, dried over magnesium sulfate and evaporated in vacuo. The residue was crystallized with ethyl acetate to give 4-hydroxy-1,2-dimethyl-1H-benzimidazole (297 mg).

1. temperaturecooling
2. waitfor 2 hours at ambient temperature
3. temperaturerefluxed for 14 hours
4. temperatureAfter cooling
5. extractionextracted with dichloromethane twice
6. washwashed with brine
7. dry with materialdried over magnesium sulfate
8. customevaporated in vacuo
9. customThe residue was crystallized with ethyl acetate