反应详情

To a solution of 3a1 (3.83 g, 12.9 mmol) in a mixture of formic acid (45 ml) and water (15 ml) was added Raney Ni (2.14 g, slurry in water). The mixture was refluxed with stirring for 3 hours. After cooling the mixture was filtered through celite and the filtrate was evaporated to dryness. The residue was partitioned between ethyl acetate and aqueous sodium bicarbonate (1M). The organic phase was dried over sodium sulfate and concentrated under reduced pressure. The concentrate was eluted through a short silica gel column with ethyl acetate. Evaporation of the solvent left 5-formyl-1-(3-(1-piperidinyl)phenyl)-benzimidazole (3.86 g, 100%) as an oil. This oil was dissolved in refluxing ethanol (15 ml). Hydroxyl amine hydrochloride (2.64 g, 38.0 mmol) and triethylamine (1.70 ml) was added and reflux was continued for 5 hours. The cooled mixture was rendered basic by addition of triethylamine. Water was added and the pricipitate was filtered off, washed with water and dried to yield 3b1 (2.89 g, 70%). M.p. 213-214° C.

1. temperatureThe mixture was refluxed
2. temperatureAfter cooling the mixture
3. filtrationwas filtered through celite
4. customthe filtrate was evaporated to dryness
5. customThe residue was partitioned between ethyl acetate and aqueous sodium bicarbonate (1M)
6. dry with materialThe organic phase was dried over sodium sulfate
7. concentrationconcentrated under reduced pressure
8. washThe concentrate was eluted through a short silica gel column with ethyl acetate
9. customEvaporation of the solvent
10. waitleft 5-formyl-1-(3-(1-piperidinyl)phenyl)-benzimidazole (3.86 g, 100%) as an oil
11. dissolutionThis oil was dissolved
12. temperaturein refluxing ethanol (15 ml)
13. temperaturereflux
14. waitwas continued for 5 hours
15. filtrationthe pricipitate was filtered off
16. washwashed with water
17. customdried