反应详情

2-(2-Methoxy-3-nitro-phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 6a (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 reaction was monitored by TLC until the disappearance of the starting materials. 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 51a (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