反应详情

The product from Step A above (22.5 g, 84.36 mmol) was dissolved in 60 mL of tetrahydrofuran and added with 125 mL of a 1.0 M NaOH aqueous solution. The mixture was stirred at room temperature for 4 d, then washed with ether (60 mL×2), acidified to pH ˜2 using a 1.0 M HCl aqueous solution. Solids were precipitated out after acidification, and collected by filtration. The solid was dissolved in methylene chloride-ethyl acetate (˜4:1, v/v). The organic solution was washed with H2O and brine, dried with Na2SO4, and concentrated in vacuo to a light yellow solid, further dried on hight vacuum, yielding 17.95 g of 4-bromo-3-methoxy-2-thiophene carboxylic acid (90%, MH+=237.0).

1. washwashed with ether (60 mL×2)
2. customSolids were precipitated out after acidification
3. filtrationcollected by filtration
4. dissolutionThe solid was dissolved in methylene chloride-ethyl acetate (˜4:1, v/v)
5. washThe organic solution was washed with H2O and brine
6. dry with materialdried with Na2SO4
7. concentrationconcentrated in vacuo to a light yellow solid
8. customfurther dried on hight vacuum