Reaktion #47218

Reaktionsgleichung

methyl 2-chloro-3,4-dihydroxybenzoate

KF

Dibromomethane

→

methyl 4-chlorobenzo[d][1,3]dioxole-5-carboxylate

Ausbeute 42.0%

Lösungsmittel

DMF

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturthe mixture was heated to 120° C. for 4 h
2. 2
   TemperaturThe mixture was cooled down to room temperature
3. 3
   Extraktionextracted with ethyl ether
4. 4
   WaschenThe combined ether layers were washed with 1M NaOH, water, brine
5. 5
   Trocknendried over anhydrous Na2SO4
6. 6
   Filtrationfiltered
7. 7
   Sonstigesolvent removed under vacuum
8. 8
   SonstigeThe crude product was absorbed onto silica
9. 9
   Sonstigepurified by flash column (silicagel, hexane

Vorschrift

To a heavy walled vial containing methyl 2-chloro-3,4-dihydroxybenzoate (899.8 mg, 4.4 mmol, 1 equiv.) in 13 mL DMF was added KF (1.29 g, 22.2 mmol, 5 equiv.) and the mixture was stirred at room temperature for 30 min. Dibromomethane (0.375 mL, 5.3 mmol, 1.2 equiv.) was added and the mixture was heated to 120° C. for 4 h. The mixture was cooled down to room temperature, diluted with water, and extracted with ethyl ether. The combined ether layers were washed with 1M NaOH, water, brine, dried over anhydrous Na2SO4, filtered and solvent removed under vacuum. The crude product was absorbed onto silica and purified by flash column (silicagel, hexane:ethyl acetate 8 Å to give 395.8 mg (42%) of methyl 4-chlorobenzo[d][1,3]dioxole-5-carboxylate as a colorless crystalline solid. See Tetrahedron Lett. 38: 3361-3364 (1978); U.S. Patent Appl. Publication No. 20050009867.

Quelle