Boron tribromide → 4-(1H-Pyrazol-1-yl)phenol

Temperature

-78 °C

1-(4-Methoxy-phenyl)-1H-pyrazole (400 mg, 2.30 mmol) was dissolved in methylene chloride (8 ml) and the solution was cooled to −78° C. Boron tribromide (1.0 M in methylene chloride, 5.05 ml) was added dropwise to the solution over about five minutes to afford a brown-colored solution. The reaction mixture was allowed to stir for about thirty minutes, the cooling bath was removed, and the mixture was allowed to stir at room temperature for about an additional three hours. The mixture was poured into water, and the resulting mixture was adjusted to about pH 8. The mixture was extracted with methylene chloride (3×25 ml), and the combined organic layers were dried over magnesium sulfate, filtered, and concentrated in vacuo. The resulting crude solid was purified by column chromatography (25% ethyl acetate/hexanes) to afford 183 mg (50% yield) of the desired product as an oil. LRMS ([M+H+])=161.1.

1. customto afford a brown-colored solution
2. customthe cooling bath was removed
3. stirringto stir at room temperature for about an additional three hours
4. additionThe mixture was poured into water
5. extractionThe mixture was extracted with methylene chloride (3×25 ml)
6. dry with materialthe combined organic layers were dried over magnesium sulfate
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customThe resulting crude solid was purified by column chromatography (25% ethyl acetate/hexanes)

ORD record

ord-e6ee05e895d84aba9357d4bdee61e6a1

Source dataset

uspto-grants-2004_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06689888B2