Reacción #471524

Ecuación de reacción

2-(2-Methoxy-5-methyl-3-nitro-phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

2-(2-methoxy-5-methyl-3-nitro-phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

5-bromothiophene-2-carboxylic acid

sodium carbonate

→

5-(3-nitro-2-methoxy-5-methyl-phenyl)thiophene-2-carboxylic acid

Rendimiento 73.6%

Disolventes

1,4-dioxane

water

Condiciones de reacción

Tratamiento posterior

1. 1
   TemperaturaThe reaction mixture was heated
2. 2
   Temperaturato reflux for 1 hour
3. 3
   ConcentraciónThe mixture was concentrated under reduced pressure
4. 4
   workup.DISSOLUTIONthe residue was dissolved in water
5. 5
   FiltraciónThe mixture was filtered
6. 6
   Otroto remove tetrakis(triphenylphosphine)palladium
7. 7
   Extracciónthe filtrate was extracted with ethyl acetate
8. 8
   Otroto form
9. 9
   Otroprecipitates
10. 10
    workup.DISSOLUTIONThe precipitates were dissolved in ethyl acetate
11. 11
    Secadodried over anhydrous magnesium sulfate
12. 12
    Filtraciónfiltered
13. 13
    Otroto remove the drying agent
14. 14
    Concentraciónconcentrated under reduced pressure

Procedimiento

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.

Fuente