反应详情

Concentrated sulfuric acid (0.441 ml; 8.27 mmol) was dropped into a suspension (35 ml) of 3.86 g (32.2 mmol) of magnesium sulfate in dichloromethane and, after completion of the dropping, the mixture was stirred at room temperature for 20 minutes. After that, 750 mg (3.91 mmol) of 3,6-dichloro-2-pyridinecarboxylic acid and dichloromethane (10 ml) solution of 3.84 ml (40.2 mmol) of tert-butyl alcohol were added to the reaction solution at room temperature followed by stirring rapidly at room temperature for 15 hours. Under ice-cooling, an aqueous solution (40 ml) of 3.0 g of sodium carbonate was dropped thereinto followed by stirring until the reaction solution became a homogeneous solution. The reaction solution was extracted with chloroform and the organic layer was washed with a saturated aqueous saline solution, dried and concentrated in vacuo. The resulting residue was purified by a silica gel column chromatography (hexane:ethyl acetate=97:3) to give 644 mg (yield: 66%) of tert-butyl 3,6-dichloro-2-pyridinecarboxylate as a white solid.

1. stirringby stirring rapidly at room temperature for 15 hours
2. temperatureUnder ice-cooling
3. stirringby stirring until the reaction solution
4. extractionThe reaction solution was extracted with chloroform
5. washthe organic layer was washed with a saturated aqueous saline solution
6. customdried
7. concentrationconcentrated in vacuo
8. customThe resulting residue was purified by a silica gel column chromatography (hexane:ethyl acetate=97:3)