反应详情

2-(2-Methoxy-3-nitro-phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 4d (4 g, 14.34 mmol), 4-bromo-furan-2-carboxylic acid 22b (2.18 g, 11.47 mmol), tetrakis(triphenylphosphine)palladium (829 mg, 0.717 mmol) and potassium carbonate (3.96 g, 28.68 mmol) were dissolved in the solvent mixture of 80 mL of 1,4-dioxane and 30 mL of water. The reaction mixture was heated to reflux for 2.5 hours. The mixture was adjusted to pH 3 with 1 M hydrochloric acid and then extracted with ethyl acetate (80 mL×3). The combined organic extracts were concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain the title compound 4-(3-nitro-2-methoxy-phenyl)-furan-2-carboxylic acid 22c (3.42 g, yield 90.7%) as a brown oil.

1. temperatureThe reaction mixture was heated
2. temperatureto reflux for 2.5 hours
3. extractionextracted with ethyl acetate (80 mL×3)
4. concentrationThe combined organic extracts were concentrated under reduced pressure
5. customThe residue was purified by silica gel column chromatography