Reaktion #10371

Reaktionsgleichung

NaHCO3

ethanol

2,3,4-trifluoro-5-methoxybenzoic acid

oxalyl chloride

→

title compound

Ausbeute 96.8%

2,3,4-Trifluoro-5-methoxybenzoic acid ethyl ester

Ausbeute 96.8%

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Einengenconcentrated
2. 2
   workup.ADDITIONThe acid chloride is then diluted with dichloromethane
3. 3
   Temperaturcooled to 0° C.
4. 4
   workup.STIRRINGThe resulting solution is stirred at room temperature for 20 hours
5. 5
   Extraktionextracted with dichloromethane
6. 6
   WaschenThe organic extracts are washed with brine
7. 7
   Trocknendried over Na2SO4
8. 8
   Filtrationfiltered
9. 9
   Einengenconcentrated under vacuum

Vorschrift

A solution of 2,3,4-trifluoro-5-methoxybenzoic acid (Hayashi et al., Bull. Chem. Soc. Jap., 1972; 45(9):2909–2914, 3.443 g, 16.7 mmol) in dichloromethane (100 mL) at 0° C. is treated with oxalyl chloride (7 mL, 80 mmol) followed by N,N-dimethylformamide (4 drops). The mixture is stirred at room temperature for 3.5 hours, concentrated to near dryness, and co-evaporated with benzene. The acid chloride is then diluted with dichloromethane, cooled to 0° C., and treated with absolute ethanol (10 mL, 170 mmol). The resulting solution is stirred at room temperature for 20 hours, poured into saturated NaHCO3 solution, and extracted with dichloromethane. The organic extracts are washed with brine, dried over Na2SO4, filtered, and concentrated under vacuum to afford the title compound (3.785 g). 1H NMR (200 MHz, CDCl3): δ 7.36–7.29 (m, 1H), 4.42 (q, 2H), 3.93 (s, 3H), 1.44 (t, 3H).

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