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

Temperature

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 dichloromethane. 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 dichloromethane
9. washThe combined organic layers were washed with brine
10. dry with materialdried (MgSO4)
11. concentrationconcentrated
12. customThe concentrate was recrystallized from ethanol

ORD record

ord-4ff4238b74784edbbe8a41715325df33

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08273736B2