Phosphorus tribromide → 5-Bromo-4-(bromomethyl)-1-(1,1-dimethylethyl)-1H-pyrazole

Temperature

0 °C

A solution of (5-bromo-1-tert-butyl-1H-pyrazol-4-yl)methanol (460 mg, 1.97 mmol) in dichloromethane (25 mL) was cooled to 0° C. and then treated with phosphorus(III)bromide (0.37 mL, 3.46 mmol), dropwise, over 5 minutes. The mixture was stirred 30 minutes at 0° C. and then 1 hour at room temp. The mixture was quenched slowly with water (50 mL), stirred 30 minutes, and then extracted with ethyl acetate (2×50 mL). The organic phase was washed with saturated aqueous sodium bicarbonate (50 mL), dried over sodium sulfate, filtered and concentrated to yield 362 mg of 5-bromo-4-(bromomethyl)-1-tert-butyl-1H-pyrazole as a clear oil. 1H NMR (400 MHz, CDCl3, δ): 7.54 (s, 1H), 4.39 (s, 2H), 1.74 (s, 9H).

1. custom1 hour
2. customat room temp
3. customThe mixture was quenched slowly with water (50 mL)
4. stirringstirred 30 minutes
5. extractionextracted with ethyl acetate (2×50 mL)
6. washThe organic phase was washed with saturated aqueous sodium bicarbonate (50 mL)
7. dry with materialdried over sodium sulfate
8. filtrationfiltered
9. concentrationconcentrated

ORD record

ord-f636b016c48549578d93adb1f609b592

Source dataset

uspto-grants-2015_03

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08993586B2