Sulfuric Acid → ethyl 3-bromo-1-(3,5-dichloropyridin-2-yl)-1H-pyrazole-5-carboxylate

To a 100 mL flask, ethyl 3-bromo-1-(3,5-dichloropyridin-2-yl)-4,5-dihydro-1H-pyrazole-5-carboxylate (2.0 g, 5.4 mmol), acetonitrile (10 mL) and 98% sulfuric acid (1.1 g, 10.9 mmol) were added. The mixture was stirred for a few minutes, and then potassium persulfate (2.4 g, 8.7 mmol) was added. The reaction mixture was heated to reflux for 5 hours. The warm (50-65° C.) reaction mixture was filtered, a cake is obtained. The cake was washed by acetonitrile (10 mL). The filtrate was concentrated to about 10 mL on rotary evaporator. Then water (50 mL) was added. The solid product was isolated by filtration, washed with 25% aqueous solution of acetonitrile (3×15 mL) and dried to give the product (1.6 g) as orange solid in 80% yield.

1. temperatureThe reaction mixture was heated
2. temperatureto reflux for 5 hours
3. temperatureThe warm
4. custom(50-65° C.) reaction mixture
5. filtrationwas filtered
6. customa cake is obtained
7. washThe cake was washed by acetonitrile (10 mL)
8. concentrationThe filtrate was concentrated to about 10 mL on rotary evaporator
9. additionThen water (50 mL) was added
10. customThe solid product was isolated by filtration
11. washwashed with 25% aqueous solution of acetonitrile (3×15 mL)
12. customdried

ORD record

ord-21a3d3291b7c47ca88778ca23361e924

Source dataset

uspto-grants-2013_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08492409B2