Boron tribromide → 2-methyl-1H-indol-5-ol

Temperature

-78 °C

To a solution of 5-methoxy-2-methyl-1H-indole (5 g, 31 mmol) in methylene chloride (100 mL) at −78° C., was slowly added a solution of BBr3 in CH2Cl2 (1.0 M, 93 mL, 93 mmol). The reaction mixture was stirred at −78° C. for 4 hours and slowly warmed to room temperature. The reaction mixture was stirred at room temperature overnight, and cooled to 0° C. The reaction was quenched carefully with water at 0° C. The aqueous layer was made basic by adding saturated sodium bicarbonate solution, and then extracted with methylene chloride (3×50 mL). The combined organic layers were dried over sodium sulfate and concentrated under reduced pressure. The crude product was purified by flash chromatography on silica gel eluting with EtOAc/Hexanes (25:75) to afford the title compound as a yellow solid (3.0 g, 60%).

1. temperatureslowly warmed to room temperature
2. stirringThe reaction mixture was stirred at room temperature overnight
3. temperaturecooled to 0° C
4. customThe reaction was quenched carefully with water at 0° C
5. additionby adding saturated sodium bicarbonate solution
6. extractionextracted with methylene chloride (3×50 mL)
7. dry with materialThe combined organic layers were dried over sodium sulfate
8. concentrationconcentrated under reduced pressure
9. customThe crude product was purified by flash chromatography on silica gel eluting with EtOAc/Hexanes (25:75)

ORD record

ord-a4fdddb46bd448d2b97f275d3ac50c63

Source dataset

uspto-grants-2006_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06995171B2