Reaction #45446

Reaction equation

sodium bicarbonate

5-bromo-2-hydroxy-benzaldehyde

hydroxylamine-O-sulfonic acid

→

desired product

5-bromo-1,2-benzisoxazole

Solvents

water

dichloromethane

ethanol

Conditions

Workup

1. 1
   workup.STIRRINGThe solution was stirred at 0° C. for 30 minutes
2. 2
   OtherThe organic layer was removed
3. 3
   Extractionthe 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
   OtherThe layers were separated
8. 8
   Extractionthe aqueous layer was extracted with dicloromethane
9. 9
   WashThe combined organic layers were washed with brine
10. 10
    Dryingdried (MgSO4)
11. 11
    Concentrationconcentrated
12. 12
    OtherThe concentrate was recrystallized from ethanol

Procedure

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)−

Source