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 (20.00 g, 90%, 54.12 mmol), potassium persulfate (23.40 g, 86.60 mmol) and acetonitrile (180 mL) were added. The reaction mixture was stirred at room temperature. The sulfuric acid (10.82 g, 108.24 mmol) was added dropwise slowly. After added completely, the reaction mixture was heated to reflux for 2 hours. The reaction mixture was concentrated by rotary evaporator to remove most acetonitrile. Water (100 mL) was added and the reaction 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 (18.73 g) as a yellow solid in 89% yield. HPLC area normalization method content is 85%.

1. additionAfter added completely
2. temperaturethe reaction mixture was heated
3. temperatureto reflux for 2 hours
4. concentrationThe reaction mixture was concentrated by rotary evaporator
5. customto remove most acetonitrile
6. additionWater (100 mL) was added
7. extractionthe reaction 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-df594dfafe81469f88a7949911a29c69

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08217179B2