反应详情

To a stirred solution of 3-acetyl-5-bromo-2,4-dimethyl-1H-pyrrole (5.33 g, 21.1 mmol, including water) in dimethoxyethane (DME; 60 mL) added water (20 mL), sodium bicarbonate (5.32 g, 63.3 mmol), 4-pyridineboronic acid [prepared according to the method of Fischer F. C. et al., J. Red. Trav. Chim. Pays-Bays, 1965, 84, 439. ] (3.11 g, 25.3 mmol) and bis(triphenylphosphine)palladium(II)chloride (1.48 g, 2.11 mmol) at room temperature under nitrogen. The mixture was heated at reflux temperature for 8 hours, 4-pyridineboronic acid (0.5 g, 4.07 mmol) and bis(triphenylphosphine)palladium(II)chloride (1.48 g, 2.11 mmol) were additionally added to the reaction mixture and stirred at reflux temperature for 6 hours. After cooling, the reaction mixture was filtered through celite pad. The filtrate was diluted with ethyl acetate (150 mL), and the whole was washed with water (50 mL). The aqueous layer was extracted with ethyl acetate (150 mL), and the combined organic layers were washed with brine (50 mL) and 10% aqueous HCl solution (100 mL×2). The combined acidic aqueous layers were neutralized with saturated aqueous NaHCO3 solution. The whole was extracted with ethyl acetate (100 mL×3), and the combined organic layers were dried over MgSO4, and concentrated in vacuo. The resulting solids were washed with diethylether to give 2.00 g of crude product, which was recrystallized from MeOH to give the title product (1. 13 g, 25% yield).

1. customprepared
2. customat room temperature
3. temperatureThe mixture was heated
4. temperatureat reflux temperature for 8 hours
5. temperatureat reflux temperature for 6 hours
6. temperatureAfter cooling
7. filtrationthe reaction mixture was filtered through celite pad
8. additionThe filtrate was diluted with ethyl acetate (150 mL)
9. washthe whole was washed with water (50 mL)
10. extractionThe aqueous layer was extracted with ethyl acetate (150 mL)
11. washthe combined organic layers were washed with brine (50 mL) and 10% aqueous HCl solution (100 mL×2)
12. extractionThe whole was extracted with ethyl acetate (100 mL×3)
13. dry with materialthe combined organic layers were dried over MgSO4
14. concentrationconcentrated in vacuo
15. washThe resulting solids were washed with diethylether
16. customto give 2.00 g of crude product, which
17. customwas recrystallized from MeOH