反应详情

温度

120 °C

A 2-necked 100 mL round bottom flask was charged with commercially available 2-acetyl-6-methoxynapthalene(5.0 g, 25 mmol) and trifluoroacetic acid (500 mmol, 38 mL) and fitted with a reflux condenser and a stopper. The solution was heated to 120° C. and sodium azide (3.25 g, 50 mmol) was added over 30 minutes. Each addition resulted in a visible exotherm. Gas evolution ceased 30 minutes after complete addition of the azide. The reaction was cooled and poured into excess saturated aqueous sodium bicarbonate. The resulting mixture was extracted (2×, ethyl acetate). The combined organic extracts were washed (2×, brine), dried (Na2SO4), filtered and concentrated in vacuo to afford a light red solid which was a mixture (~5:1) of the respective N-acetyl-6-methoxynapthylamine and N-methylaminocarbonyl-6-methoxynapthalene. The mixture was carried on without purification. The unpurified solid (4.51 g, 20.9 mmol) was dissolved in hot ethanol (100 mL). Water (15 mL) and concentrated sulfuric acid (2.24 g, 41.9 mmol) were added and the reaction heated at reflux for 24 h during which time a thick precipitate formed. The reaction was cooled to 0° C. and the solid 2-amino-6-methoxynapthalene hydrogen sulfate salt was collected by filtration. The salt was neutralized by partitioning between aqueous sodium hydroxide(15.8 g, 0.396 mmol in 200 mL of water) and ethyl acetate. The layers were separated and the aqueous layer extracted with ethyl acetate (2×). The organic layers were combined, washed (brine, 3×), dried (Na2SO4), filtered and concentrated in vacuo to afford a purple solid. Recrystallization from ethyl acetate and acetone gave the title compound in three fractions (2.64 g, 61%) as a light beige solid. mp 133°-136° C.

1. customfitted with a reflux condenser
2. additionEach addition
3. customresulted in a visible exotherm
4. temperatureThe reaction was cooled
5. extractionThe resulting mixture was extracted (2×, ethyl acetate)
6. washThe combined organic extracts were washed (2×, brine)
7. dry with materialdried (Na2SO4)
8. filtrationfiltered
9. concentrationconcentrated in vacuo
10. customto afford a light red solid which
11. customThe mixture was carried on without purification
12. temperaturethe reaction heated
13. temperatureat reflux for 24 h during which time a thick precipitate
14. customformed
15. temperatureThe reaction was cooled to 0° C.
16. filtrationthe solid 2-amino-6-methoxynapthalene hydrogen sulfate salt was collected by filtration
17. customThe layers were separated
18. extractionthe aqueous layer extracted with ethyl acetate (2×)
19. washwashed (brine, 3×)
20. dry with materialdried (Na2SO4)
21. filtrationfiltered
22. concentrationconcentrated in vacuo
23. customto afford a purple solid
24. customRecrystallization from ethyl acetate and acetone