Reaktion #45446

Reaktionsgleichung

sodium bicarbonate

5-bromo-2-hydroxy-benzaldehyde

hydroxylamine-O-sulfonic acid

→

desired product

5-bromo-1,2-benzisoxazole

Lösungsmittel

water

dichloromethane

ethanol

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGThe solution was stirred at 0° C. for 30 minutes
2. 2
   SonstigeThe organic layer was removed
3. 3
   Extraktionthe aqueous layer was extracted with dichloromethane
4. 4
   workup.ADDITIONThe aqueous layer was treated with additional dichloromethane (50 mL)
5. 5
   workup.STIRRINGstirring
6. 6
   workup.WAITwas continued for one hour
7. 7
   SonstigeThe layers were separated
8. 8
   Extraktionthe aqueous layer was extracted with dicloromethane
9. 9
   WaschenThe combined organic layers were washed with brine
10. 10
    Trocknendried (MgSO4)
11. 11
    Einengenconcentrated
12. 12
    SonstigeThe concentrate was recrystallized from ethanol

Vorschrift

A solution of 5-bromo-2-hydroxy-benzaldehyde (2.0 g, 10 mmol) in ethanol (10 mL) at room temperature was treated with hydroxylamine-O-sulfonic acid (1.69 g, 15 mmol), stirred for 20 minutes, diluted with dichloromethane (50 mL), cooled to 0° C. and treated with a solution of sodium bicarbonate (3 g) in water (25 mL). The solution was stirred at 0° C. for 30 minutes. The organic layer was removed and the aqueous layer was extracted with dichloromethane. The aqueous layer was treated with additional dichloromethane (50 mL) and stirring was continued for one hour. The layers were separated and the aqueous layer was extracted with dicloromethane. The combined organic layers were washed with brine, dried (MgSO4) and concentrated. The concentrate was recrystallized from ethanol to give 970 mg (49%) yield of the desired product. MS (ESI(−)) m/e 195.9, 197.9 (M−H)−

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