反应详情

LiAlH4 (1.0 m in THF, 10 mL, 10 mmol) was added dropwise to a suspension of 5-benzimidazolecarboxylic acid (500 mg, 3.08 mmol) in THF (20 mL) at 0° C. The reaction mixture was warmed to room temperature and stirred for 24 h followed by heating at 50° C. for an addition 24 h. MeOH (4×5 mL) was added and the solution was concentrated between each addition. The resulting brown syrup was dried in vacuo for 3 h. The syrup was dissolved in 100:1—CH2Cl2:MeOH, filtered through celite and concentrated to a light brown foam (300 mg, 66%). To a stirred solution of the crude alcohol (300 mg, 2.0 mmol) in CH2Cl2 (10 mL) and MeOH (0.8 mL) was added manganese (IV) oxide (85%, 2.05 g, 20 mmol). The suspension was heated to 40° C. for 18 h, cooled to room temperature and filtered through celite. The filtrant was concentrated to a light yellow foam (260 mg). Purification of the crude material by column chromatography on silica gel (200:1:1—EtOAc:MeOH:NH4OH) gave the title compound as a white powder (139 mg, 60%). 1H NMR (300 MHz, CD3OD) δ 10.0 (s, 1H), 8.38 (s, 1H), 8.20 (s, 1H), 7.87 (d, 1H, J=9.0 Hz), 7.75 (d, 1H, J=9.0 Hz).

1. temperatureby heating at 50° C. for an addition 24 h
2. concentrationthe solution was concentrated between each addition
3. customThe resulting brown syrup was dried in vacuo for 3 h
4. dissolutionThe syrup was dissolved in 100
5. filtration1—CH2Cl2:MeOH, filtered through celite
6. concentrationconcentrated to a light brown foam (300 mg, 66%)
7. temperatureThe suspension was heated to 40° C. for 18 h
8. temperaturecooled to room temperature
9. filtrationfiltered through celite
10. concentrationThe filtrant was concentrated to a light yellow foam (260 mg)
11. customPurification of the crude material by column chromatography on silica gel (200:1:1—EtOAc:MeOH:NH4OH)