Reacción #1061902

Ecuación de reacción

hydrochloric acid

potassium carbonate

3-hydroxy-4-methoxybenzoic acid

tert-butyldimethylsilyl chloride

imidazole

→

3-(tert-Butyldimethylsilyloxy)-4-methoxybenzoic acid

Disolventes

Hexane

methanol

water

methanol

ethyl acetate

DMF

Condiciones de reacción

Tratamiento posterior

1. 1
   Lavadothe resulting mixture washed with water
2. 2
   workup.ADDITIONthe extracts added to the hexane layer from the first extraction
3. 3
   LavadoThe combined extracts were washed with small amount of water
4. 4
   OtroDuring the washing some precipitate formed
5. 5
   Otrocrushed ice
6. 6
   workup.ADDITIONwas added
7. 7
   OtroThe organic phase was separated
8. 8
   Extracciónthe aqueous layer extracted two times with ethyl acetate
9. 9
   LavadoThe combined extracts were washed with a mixture of brine and water (1:1)
10. 10
    Otrodried
11. 11
    OtroTLC (silica gel, hexane/ethyl acetate=2:1) of the product gave one spot

Procedimiento

A mixture of 3-hydroxy-4-methoxybenzoic acid (6.726 g, 40 mmol), tert-butyldimethylsilyl chloride (13.26 g, 88 mmol), imidazole (10.893 g, 160 mmol) and DMF (40 mL) was stirred at room temperature for 18 hr. Hexane was added and the resulting mixture washed with water. The aqueous layer was reextracted two times with hexane and the extracts added to the hexane layer from the first extraction. The combined extracts were washed with small amount of water. During the washing some precipitate formed. The organic phase, together with the precipitate, was dissolved in small amount of methanol and rotary evaporated. The residue was taken into methanol (100 ml) and stirred at room temperature with potassium carbonate (10 g) and water (3 ml) for 1.5 hr. A mixture of ethyl acetate and crushed ice was added and the mixture was carefully acidified with dilute hydrochloric acid (the final pH of the aqueous layer was 3.5). The organic phase was separated and the aqueous layer extracted two times with ethyl acetate. The combined extracts were washed with a mixture of brine and water (1:1) and dried. TLC (silica gel, hexane/ethyl acetate=2:1) of the product gave one spot having an Rf of 0.2. NMR(δ): 0.18 (s, 6H), 1.00 (s, 9H), 3.90 (s, 3H).

Fuente