反应详情

2,3-Diaminobenzyl alcohol 2 (3.45 g, 25 mmol) was dissolved in a MeOH/H2O mixture (200 mL, v/v=1:1). Acetic acid (3 mL), 2-nitro-benzaldehyde (5.3 g, 35 mmol) in MeOH (50 mL) and Cu(OAc)2.H2O (7.0 g, 35 mmol) in water (100 mL), were added sequentially to the stirring solution. It was then heated to reflux under vigorous stirring for 3 hr, after which a pale yellow precipitate was formed. The mixture was filtered hot and then washed with water to afford a gray-yellow solid. The precipitate was redissolved in EtOH (150 mL) and concentrated HCl (24 mL), and then a solution of Na2S.9H2O (12.8 g, 50 mmol) in water (100 mL) was added. The mixture was heated at reflux for 1 hour resulting in a black slurry. It was then allowed to cool to room temperature, and filtered through a pad of celite to remove the resulting CuS. The filtrate was neutralized with ammonium hydroxide to pH=8-9 and then concentrated by rotary evaporation to yield a green-yellow precipitate. After filtration and vacuum evaporation, 4-hydroxymethyl-2-(2-nitrophenyl)-benzimidazole (5.55 g, 82%) was obtained as a green-yellow solid. Rf=0.28 (hexane/ethyl acetate=1:2); 1H NMR (200 MHz, DMSO) δ 4.84 (broad s, 2H), 5.22 (broad s, 1H), 7.28 (m, 2H), 7.49 (d, J=6.8 Hz, 1H), 7.71-8.06 (m, 4H), 12.93 (broad s, 1H); HRMS: Calcd. for C14H11N3O3 269.0800, found 269.0845.

1. temperatureIt was then heated
2. temperatureto reflux
3. customafter which a pale yellow precipitate was formed
4. filtrationThe mixture was filtered hot
5. washwashed with water
6. customto afford a gray-yellow solid
7. temperatureThe mixture was heated
8. temperatureat reflux for 1 hour
9. customresulting in a black slurry
10. filtrationfiltered through a pad of celite
11. customto remove the resulting CuS
12. concentrationconcentrated by rotary evaporation
13. customto yield a green-yellow precipitate
14. filtrationAfter filtration and vacuum evaporation