Sodium Carbonate → 5-(3-Nitro-2-methoxy-5-methyl-phenyl)thiophene-2-carboxylic acid

Participants

Reaction Steps

2-(2-Methoxy-5-methyl-3-nitro-phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 24a (4.0 g, 14.5 mmol), 5-bromothiophene-2-carboxylic acid (1.0 g, 4.8 mmol), tetrakis(triphenylphosphine)palladium (0.276 g, 0.24 mmol) and sodium carbonate (1.01 g, 9.6 mmol) were dissolved in 30 mL of 1,4-dioxane and 10 mL of water. The reaction mixture was heated to reflux for 1 hour. The reaction was monitored by TLC until the disappearance of the starting materials. The mixture was concentrated under reduced pressure and the residue was dissolved in water. The mixture was filtered to remove tetrakis(triphenylphosphine)palladium and the filtrate was extracted with ethyl acetate. The aqueous layer was acidified to form precipitates. The precipitates were dissolved in ethyl acetate, dried over anhydrous magnesium sulfate, filtered to remove the drying agent and concentrated under reduced pressure to obtain the title compound 5-(3-nitro-2-methoxy-5-methyl-phenyl)thiophene-2-carboxylic acid 24b (1.03 g, 73.6%) as a yellow solid.

Provenance & Evidence