反应详情

温度

-78 °C

To a solution of 2,4,5-tribromo-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole (5.0 g, 11.5 mmol) in tetrahydrofuran (200 ml) at −78° C. is added phenyl lithium (7.0 ml, 12.6 mmol, 1.8 M in THF). After 30 minutes stirring at −78° C. CO2-pellets (˜3.0 g) are added. The mixture is allowed to warm to room temperature, water is added, and the pH is carefully adjusted with 6N HCl (aqueous) to pH=5. The mixture is extracted with ethyl acetate (2×50 ml) and the combined organic layer is washed with brine, dried over MgSO4, filtered and evaporated in vacuo. The crude 4,5-dibromo-1-(2-trimethylsilanyl-ethoxymethyl)-1H-imidazole-2-carboxylic acid is obtained as a yellow oil, and used without further purification 4.2 g, 91%, LC/MS ESI m/z (M−H)−398.8.

1. temperatureto warm to room temperature
2. extractionThe mixture is extracted with ethyl acetate (2×50 ml)
3. washthe combined organic layer is washed with brine
4. dry with materialdried over MgSO4
5. filtrationfiltered
6. customevaporated in vacuo