反应详情

2-(2-Methoxy-3-nitro-phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 4d (0.81 g, 2.9 mmol), 4-bromo-thiophene-2-carboxylic acid (0.3 g, 1.45 mmol), tetrakis (triphenylphosphine)palladium (80 mg, 0.073 mmol) and sodium carbonate (0.31 g, 2.9 mmol) were dissolved in a solvent mixture of 20 mL of 1,4-dioxane and 10 mL of water. The reaction was heated to reflux for 0.5 hours. The mixture was adjusted to pH 3 with 1 N hydrochloric acid and extracted with ethyl acetate (20 mL×3). The combined organic extracts were concentrated under reduced pressure and the residue was purified by silica gel column chromatography to obtain the title compound 4-(3-nitro-2-methoxy-phenyl)-thiophene-2-carboxylic acid 19a (0.54 g) as a brown oil, which was directly used in the next step.

1. temperatureThe reaction was heated
2. temperatureto reflux for 0.5 hours
3. extractionextracted with ethyl acetate (20 mL×3)
4. concentrationThe combined organic extracts were concentrated under reduced pressure
5. customthe residue was purified by silica gel column chromatography