Sodium Hydroxide → 3-Bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxylic acid

To a 500 mL flask, ethyl 3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxylate (22.00 g, 83%, 55.23 mmol) and ethanol (100 mL) were added. The sodium hydroxide solution (2.20 g, 55.23 mmol, dissolved into water (100 mL)) was added dropwise. After being stirred for 2 hours at room temperature, the reaction mixture was concentrated by rotary evaporator to remove ethanol. The residue was extracted with ethyl acetate (30 mL) and the aqueous layer was acidified with concentrated hydrochloric acid to pH=3. Then the aqueous solution was extracted with ethyl acetate (3×100 mL) again. The combined organic layers were washed with saturated brine (100 mL), dried over anhydrous magnesium sulfate and concentrated by rotary evaporator to give the product (15.51 g) as a light yellow solid in 91% yield. HPLC area normalization method content is 98%.

1. concentrationthe reaction mixture was concentrated by rotary evaporator
2. customto remove ethanol
3. extractionThe residue was extracted with ethyl acetate (30 mL)
4. extractionThen the aqueous solution was extracted with ethyl acetate (3×100 mL) again
5. washThe combined organic layers were washed with saturated brine (100 mL)
6. dry with materialdried over anhydrous magnesium sulfate
7. concentrationconcentrated by rotary evaporator

ORD record

ord-20172e478e6e4cc8bc282c7bba7bdfa6

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08217179B2