反应详情

温度

25 °C

The procedure of Mitchell et at., J. Org. Chem. 44(25):4733 (1979) was adapted. To a stirred suspension of 2-hydroxybenzimidazole (134 mg, 1.00 mmol, Aldrich) in dry DMF (3 mL) was added dropwise a solution of N-bromosuccinimide (187 mg, 1.05 mmol, Aldrich) in dry DMF (1 mL) and then it was stirred at 25° C. for 0.5 h resulting a light yellow solution. The solution was allowed to stand at 25° C. for 24 h to give a brown yellow solution which was poured into 20 mL ice water and collected by filtration and washed with distilled water (2×1 mL) followed by 95% ethanol (2×1 mL), affording 188 mg (88%) of crude title compound containing 5% dibromo-2-hydroxybenzimidazole by NMR. A 188 mg sample of crude product was dissolved into 1N NaOH (5 ml) and then acidified to pH=2 with 4N HCl giving a white creamy precipitate. It was collected by filtration and washed with distilled water (2×1 mL) followed by 95% ethanol (2×1 mL) and dried in the air at 50° C. for 8 h, giving 180 mg of title compound (containing 4% di-bromo-2-hydroxybenzimidazole by NMR) as a white powder. Crystallization from hot methanol gave white microcrystals of purer title compound (containing 3% di-bromo-2-hydroxy-benzimidazole by NMR). Mp: 305°-7° C.; IR (KBr, cm-1): 3425, 3181, 3012, 1756, 1693, 1481. 1H NMR (DMSO-d6): δ 6.854 (d, J=8.1 Hz, 1H); 7.038-7.082 (m, 2H); 10.768 (s, 2H). HRMS: calcd for C7H5BrN2O (M+) m/z: 211.9584 found: 211.9591. Potency relative to DCK: 1%.

1. customresulting a light yellow solution
2. waitto stand at 25° C. for 24 h
3. customto give a brown yellow solution which
4. filtrationcollected by filtration
5. washwashed with distilled water (2×1 mL)
6. customaffording 188 mg (88%) of crude title compound
7. filtrationIt was collected by filtration
8. washwashed with distilled water (2×1 mL)
9. customdried in the air at 50° C. for 8 h