反应详情

2-(2-Methoxy-3-nitro-phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 6a (4 g, 14.34 mmol), 4-bromo-furan-2-carboxylic acid 28b (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 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 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 28c (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