反应详情

3,5-Dibromopyridine (30.5 g, 0.12 mol) was dissolved in dichloromethane (80 mL) and methyltrioxorhenium (150 mg, 0.603 mmol) was added. Hydrogen peroxide (aqueous, 30%, 27 mL) was added slowly over 5 minutes, and the mixture was stirred at ambient temperature for 3 hours. An additional 40 mL of 30% hydrogen peroxide was added, and the reaction was stirred for 16 hours. Manganese dioxide (100 mg) was added, and the suspension was stirred for 40 minutes. The mixture was extracted with dichloromethane, dried (sodium sulfate), filtered and concentrated under reduced pressure. Ethyl acetate was added, and the suspension was refluxed for 30 minutes until solids dissolved, and then the mixture was allowed to cool to ambient temperature and left for 48 hours. 3,5-Dibromopyridine-1-oxide (28.05 g, 79%) was collected by vacuum filtration. MS (LC-MS) m/z 254 (M+H)+. 3,5-Dibromopyridine-1-oxide (25.09 g, 0.099 mol) was then dissolved in acetonitrile (200 mL) and triethylamine (28 mL, 0.198 mol) and trimethylsilylcyanide (40 mL, 0.297 mol) were added. The reaction was stirred for 16 hours, diluted with dichloromethane, aqueous sodium carbonate, water, and then filtered through diatomaceous earth eluting with dichloromethane. The mixture was extracted with dichloromethane and the organics were washed with brine, dried (sodium sulfate), filtered and concentrated under reduced pressure. Purification by silica gel chromatography (30-70% ethyl acetate in hexanes) provided the title compound. MS (LC-MS) m/z 263 (M+H)+.

1. stirringthe reaction was stirred for 16 hours
2. stirringthe suspension was stirred for 40 minutes
3. extractionThe mixture was extracted with dichloromethane
4. dry with materialdried (sodium sulfate)
5. filtrationfiltered
6. concentrationconcentrated under reduced pressure
7. additionEthyl acetate was added
8. temperaturethe suspension was refluxed for 30 minutes until solids
9. dissolutiondissolved
10. temperatureto cool to ambient temperature
11. waitleft for 48 hours
12. filtration3,5-Dibromopyridine-1-oxide (28.05 g, 79%) was collected by vacuum filtration
13. stirringThe reaction was stirred for 16 hours
14. filtrationfiltered through diatomaceous earth
15. washeluting with dichloromethane
16. extractionThe mixture was extracted with dichloromethane
17. washthe organics were washed with brine
18. dry with materialdried (sodium sulfate)
19. filtrationfiltered
20. concentrationconcentrated under reduced pressure
21. customPurification by silica gel chromatography (30-70% ethyl acetate in hexanes)