Reaktion #76369

Reaktionsgleichung

HCl

tert-Butyllithium

2-bromo-3,4,5-trimethoxybenzoic acid

2-Bromo-3,4,5-trimethoxybenzoic Acid

benzyl chloroformate

→

product

2-Carbobenzyloxy-3,4,5-trimethoxybenzoic Acid

Lösungsmittel

THF

Water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwhile maintaining the temperature of the mixture below −95° C
2. 2
   workup.ADDITIONAfter the addition
3. 3
   Temperaturto warm to 0° C
4. 4
   ExtraktionThe mixture is extracted with ethyl acetate (5×100 mL)
5. 5
   TrocknenThe organic phases are dried over anhydrous Na2SO4
6. 6
   Einengenconcentrated in vacuo
7. 7
   SonstigeThe mixture is purified by flash chromatography

Vorschrift

tert-Butyllithium (1.7M solution in pentane, 15 mmol) is added to a solution of 2-bromo-3,4,5-trimethoxybenzoic acid 5 (5 mmol) in 50 mL of THF, while maintaining the temperature of the mixture below −95° C. After the addition is completed, the mixture is allowed to warm to −78° C. After 30 minutes, benzyl chloroformate (5 mmol) is added in one portion, and the mixture is allowed to warm to 0° C. Water (50 mL) is added, and then the pH of the mixture is carefully adjusted to 3 using 0.1 M HCl. The mixture is extracted with ethyl acetate (5×100 mL). The organic phases are dried over anhydrous Na2SO4 and concentrated in vacuo. The mixture is purified by flash chromatography to give the product as a colorless oil.

Quelle