Reaktion #1877129

Reaktionsgleichung

hydrogen chloride

Oxalyl chloride

3-[(4-fluorophenyl)sulfonyl]propanoic acid

AlCl3

→

6-fluoro-2,3-dihydro-4H-1-benzothiopyran-4-one

Ausbeute 93.3%

Lösungsmittel

water

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Einengenwas concentrated under reduced pressure to a residue
2. 2
   Temperaturcooled to 0° C. in an ice bath
3. 3
   workup.ADDITIONCS2 (1 mL) was added
4. 4
   Temperaturto warm to room temperature
5. 5
   workup.STIRRINGstirred over night
6. 6
   workup.STIRRINGstirred
7. 7
   Extraktionextracted with dichloromethane (3×150 mL)
8. 8
   Waschenwashed with brine (1×100 mL) and water (1×100 mL)
9. 9
   Trocknendried (sodium sulfate)
10. 10
    Einengenconcentrated to a yellow solid
11. 11
    SonstigeThe solid was purified by flash column chromatography on 100 g silica gel
12. 12
    Wascheneluting 10% ethyl acetate in hexanes

Vorschrift

3-[(4-fluorophenyl)sulfonyl]propanoic acid (3 g, 15 mmol) was dissolved in dichloromethane (30 mL) and cooled to 0° C. in an ice bath. Oxalyl chloride (10 mL) was added slowly, dimethyl formamide (1 drop) was added and the reaction mixture was stirred at 0° C. for 0.5 hours. At which point the reaction was concentrated under reduced pressure to a residue, then resuspended in dichloromethane and cooled to 0° C. in an ice bath, CS2 (1 mL) was added and AlCl3 (4 g, 15 mmol) was added slowly. The reaction mixture was then allowed to warm to room temperature and stirred over night. Ice chips and water (250 mL) were added and stirred. Concentrated hydrogen chloride was added until pH of 2, and extracted with dichloromethane (3×150 mL). Organics were combined, washed with brine (1×100 mL) and water (1×100 mL), dried (sodium sulfate), and concentrated to a yellow solid. The solid was purified by flash column chromatography on 100 g silica gel, eluting 10% ethyl acetate in hexanes to give 6-fluoro-2,3-dihydro-4H-1-benzothiopyran-4-one (2.55 g, 93%). 1H NMR (CDCl3, 300 MHz): δ 7.80–7.76 (m, 1H), 7.27–7.23 (m, 2H), 7.15–7.09 (m, 1H), 3.23 (t, 2H, J=6.4 Hz), 2.97 (t, 2H, J=6.4 Hz) ppm.

Quelle