反应详情

温度

-10 °C

Under a nitrogen atmosphere, sodium borohydride (0.14 g, 3.7 mmol) was added portionwise to a solution of ethyl 2-(3,5-dibromothiophen-2-yl)-2-oxoacetate (7a) (0.42 g, 1.24 mmol) in anhydrous tetrahydrofuran (10 mL), previously cooled to −10° C. After 30 minutes stirring, a few drops of 1 M hydrochloric acid were added and the resulting precipitate was filtered. The filtrate was concentrated in vavuo. The residue was dissolved in brine, and extracted with ethyl acetate (2×20 mL). The organic layer was dried over sodium sulfate, filtered, and evaporated to dryness. The residue was purified by flash chromatography on silica gel (cyclohexane/ethyl acetate: 80/20) to provide ethyl 2-(3,5-dibromothiophen-2-yl)-2-hydroxyacetate (0.32 g, 0.93 mmol, 75%).

1. filtrationthe resulting precipitate was filtered
2. concentrationThe filtrate was concentrated in vavuo
3. dissolutionThe residue was dissolved in brine
4. extractionextracted with ethyl acetate (2×20 mL)
5. dry with materialThe organic layer was dried over sodium sulfate
6. filtrationfiltered
7. customevaporated to dryness
8. customThe residue was purified by flash chromatography on silica gel (cyclohexane/ethyl acetate: 80/20)