Phosphorus tribromide → 5-(Bromomethyl)-1-methyl-3-nitro-1H-pyrazole

Temperature

0 °C

A 25-mL round-bottomed flask equipped with a magnetic stirrer and reflux condenser was purged with nitrogen and charged with 156c (0.56 g, 3.6 mmol) and chloroform (10 mL). The reaction was cooled to 0° C. using an ice bath and phosphorous tribromide (0.98 g, 3.6 mmol) was added dropwise. The cooling bath was removed and the reaction stirred at reflux for 3 h. After this time, the reaction was cooled to 0° C. and diluted with methylene chloride (25 mL). Saturated aqueous sodium bicarbonate was added until a pH of 8.5 was reached. The layers were separated, and the aqueous layer was extracted with methylene chloride (3×25 mL). The combined organic layers were washed with brine (30 mL), dried over sodium sulfate and concentrated under reduced pressure to afford a quantitative yield (0.79 g) of 156d as an off-white solid: MS (ESI+) m/z 222.1 (M+H).

1. customA 25-mL round-bottomed flask equipped with a magnetic stirrer
2. temperaturereflux condenser
3. customwas purged with nitrogen
4. customThe cooling bath was removed
5. temperatureat reflux for 3 h
6. temperatureAfter this time, the reaction was cooled to 0° C.
7. additiondiluted with methylene chloride (25 mL)
8. additionSaturated aqueous sodium bicarbonate was added until a pH of 8.5
9. customThe layers were separated
10. extractionthe aqueous layer was extracted with methylene chloride (3×25 mL)
11. washThe combined organic layers were washed with brine (30 mL)
12. dry with materialdried over sodium sulfate
13. concentrationconcentrated under reduced pressure

ORD record

ord-d808dc2fbc5b4bc794e3bdbfc9590eb2

Source dataset

uspto-grants-2013_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08618107B2