反应详情

温度

60 °C

4-Bromo-3-dibromomethyl-benzoic acid ethyl ester (6.4 g, 16 mmol) was dissolved in EtOH (200 mL) and heated to 60° C. Silver nitrate (6.80 g, 40 mmol), prepared as a solution in H2O (50 mL), was added dropwise, resulting in a precipitate. After 1 hour, the mixture was decanted, and the precipitate was washed with EtOH (3×50 mL) and decanted after each wash. The combined EtOH solution was treated with 1N aqueous HCl (40 mL), which resulted in additional precipitate formation. The mixture was filtered, and the filtrate was concentrated and partitioned between EtOAc and H2O. The aqueous layer was separated and extracted with EtOAc, and the combined organic layers were concentrated. The crude material was dissolved in MeOH (100 mL) and treated with 2N aqueous H2SO4 (15 mL) for 1 hour at room temperature. After work-up, the crude material was purified by silica gel chromatography to give a mixture of the aldehyde and the dimethyl acetal. The mixture was dissolved in 1,4-dioxane and treated with 2N aqueous H2SO4 (80 mL), and stirred overnight at room temperature. The solution was diluted with EtOAc and H2O, and the organic layer was separated, dried, and concentrated to give 4-bromo-3-formyl-benzoic acid ethyl ester.

1. additionwas added dropwise
2. customresulting in a precipitate
3. customthe mixture was decanted
4. washthe precipitate was washed with EtOH (3×50 mL)
5. customdecanted after each wash
6. additionThe combined EtOH solution was treated with 1N aqueous HCl (40 mL), which
7. customresulted in additional precipitate formation
8. filtrationThe mixture was filtered
9. concentrationthe filtrate was concentrated
10. custompartitioned between EtOAc and H2O
11. customThe aqueous layer was separated
12. extractionextracted with EtOAc
13. concentrationthe combined organic layers were concentrated
14. dissolutionThe crude material was dissolved in MeOH (100 mL)
15. additiontreated with 2N aqueous H2SO4 (15 mL) for 1 hour at room temperature
16. customAfter work-up, the crude material was purified by silica gel chromatography
17. customto give
18. customthe organic layer was separated
19. customdried
20. concentrationconcentrated