反应详情

A 500 ml., three-necked, round-bottomed flask equipped with a thermometer, magnetic stirring bar, reflux condenser, and means for providing a nitrogen atmosphere was charged with a solution of 2,3-benzofuran, 19.0 g. (0.161 mole) in 190 ml. (186 g., 2.35 mole) of pyridine. The reaction system was purged with nitrogen and kept under nitrogen atmosphere throughout the course of reaction. Then freshly cut sodium metal, 11.3 g. (0.490 mole), was added, and the mixture was stirred magnetically and heated with a silicon-oil bath at 190° (reaction mixture temperature 117°) for 4 hours. After cooling to room temperature, the black reaction mixture was treated by successive dropwise addition of 100 ml. of pyridine, 50 ml. of 50% (v/v) pyridine-water, and 100 ml. of water. The resulting red-brown reaction mixture was extracted with 400 ml. of ether. The pyridine-water layer was acidified with excess (750 ml.) of 6 N HCl solution, while the reaction temperature was kept between 20°-30° with an ice-water bath. The acidified mixture was extracted with four 300 ml.-portions of ether. The combined ethereal extracts were washed with 200 ml of 6 N HCl solution and three 200 ml.-portions of water, dried over MgSO4 and concentrated to give 15.3 g. of yellow-brown oil, which was further purified by distillation via a 5" Vigreux column giving rise to 11.7 g. (62% yield) of colorless product, bp12mm 72°-73°.

1. custom, three-necked, round-bottomed flask equipped with a thermometer, magnetic stirring bar
2. temperaturereflux condenser
3. customfor providing a nitrogen atmosphere
4. customThe reaction system was purged with nitrogen
5. customkept under nitrogen atmosphere throughout the course of reaction
6. addition(0.490 mole), was added
7. temperatureheated with a silicon-oil bath at 190°
8. custom(reaction mixture temperature 117°) for 4 hours
9. additionthe black reaction mixture was treated by successive dropwise addition of 100 ml
10. extractionThe resulting red-brown reaction mixture was extracted with 400 ml
11. customwas kept between 20°-30° with an ice-water bath
12. extractionThe acidified mixture was extracted with four 300 ml
13. washThe combined ethereal extracts were washed with 200 ml of 6 N HCl solution and three 200 ml
14. dry with material-portions of water, dried over MgSO4
15. concentrationconcentrated
16. customto give 15.3 g
17. distillationof yellow-brown oil, which was further purified by distillation via a 5" Vigreux column
18. customgiving rise to 11.7 g