Reaktion #46196

Reaktionsgleichung

3,4,5-trihydroxy-benzoic acid methyl ester

Me2SO4

NaOH

H2SO4

→

methyl 3,4-dihydroxy-5-methoxybenzoate

Ausbeute 47.0%

Lösungsmittel

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwas cooled to 0° C
2. 2
   Filtrationfiltered
3. 3
   ExtraktionThe filtrate was extracted with EtOAc (500 mL×3)
4. 4
   TrocknenThe combined organic layers were dried over anhydrous Na2SO4
5. 5
   Sonstigeevaporated under reduced pressure

Vorschrift

To a solution of 3,4,5-trihydroxy-benzoic acid methyl ester (50 g, 0.27 mol) and Na2B4O7 (50 g) in water (1000 mL) was added Me2SO4 (120 mL) and aqueous NaOH solution (25%, 200 mL) successively at room temperature. The mixture was stirred at room temperature for 6 h before it was cooled to 0° C. The mixture was acidified to pH ˜2 by adding conc. H2SO4 and then filtered. The filtrate was extracted with EtOAc (500 mL×3). The combined organic layers were dried over anhydrous Na2SO4 and evaporated under reduced pressure to give methyl 3,4-dihydroxy-5-methoxybenzoate (15.3 g 47%), which was used in the next step without further purification.

Quelle