5-Bromosalicylaldehyde → 5-Bromo-1,2-benzoxazole

Temperatur

0 °C

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)−

1. stirringThe solution was stirred at 0° C. for 30 minutes
2. customThe organic layer was removed
3. extractionthe aqueous layer was extracted with dichloromethane
4. additionThe aqueous layer was treated with additional dichloromethane (50 mL)
5. stirringstirring
6. waitwas continued for one hour
7. customThe layers were separated
8. extractionthe aqueous layer was extracted with dicloromethane
9. washThe combined organic layers were washed with brine
10. dry with materialdried (MgSO4)
11. concentrationconcentrated
12. customThe concentrate was recrystallized from ethanol

ORD-Eintrag

ord-d2a564846363457bbd5a6780f7989129

Quelldatensatz

uspto-grants-2010_06

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US07737160B2