Sulfuric Acid → Ethyl 3-Bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylate

To a 500 mL flask, ethyl 3-bromo-1-(3-chloro-2-pyridinyl)-4,5-dihydro-1H-pyrazole-5-carboxylate (22.22 g, 90%, 60 mmol), potassium persulfate (25.92 g, 96 mmol) and acetonitrile (180 mL) were added. The reaction mixture was stirred at room temperature. The concentrated sulfuric acid (12 g) was added dropwise. After added completely, the reaction mixture was heated to reflux for 2 hours. The mixture was concentrated by rotary evaporator to remove most acetonitrile. Water (100 mL) was added and then the mixture was extracted with ethyl acetate (3×150 mL). The combined organic layers were washed with saturated sodium bicarbonate solution (100 mL) and saturated brine (100 mL), dried over anhydrous magnesium sulfate and concentrated by rotary evaporator to give the product (21.50 g) as a yellow solid in 90% yield. HPLC area normalization method content is 83%.

1. additionAfter added completely
2. temperaturethe reaction mixture was heated
3. temperatureto reflux for 2 hours
4. concentrationThe mixture was concentrated by rotary evaporator
5. customto remove most acetonitrile
6. additionWater (100 mL) was added
7. extractionthe mixture was extracted with ethyl acetate (3×150 mL)
8. washThe combined organic layers were washed with saturated sodium bicarbonate solution (100 mL) and saturated brine (100 mL)
9. dry with materialdried over anhydrous magnesium sulfate
10. concentrationconcentrated by rotary evaporator

ORD record

ord-2ce2f3deb00746deba8528e7d85078fe

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08217179B2