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

To a 100 mL flask, pentyl 3-bromo-1-(3-chloro-2-pyridinyl)-4,5-dihydro-1H-pyrazole-5-carboxylate (5.00 g, 97%, 12.94 mmol), ethanol (30 mL), water (30 mL) and sodium hydroxide (0.52 g, 12.94 mmol) were added. The reaction mixture was stirred for 6 hours at room temperature. The reaction mixture was concentrated by rotary evaporator to remove ethanol. Then water (250 mL) was added. Aqueous solution was extracted with ethyl acetate (100 mL), acidified with concentrated hydrochloric acid to pH=2 and extracted with dichloromethane (3×200 mL) again. The combined organic layers were dried over anhydrous magnesium sulfate and concentrated by rotary evaporator to give 3-bromo-1-(3-chloro-2-pyridinyl)-1H-pyrazole-5-carboxylic acid (3.60 g) as a white solid in 90% yield. HPLC area normalization method content is 98% (Analytical condition: chromatographic column: ZORBAX Eclipse XDB-C8 4.6×150 mm 5 μm, mobile phase:the ratio of acetonitrile to water is 70:30).

1. concentrationThe reaction mixture was concentrated by rotary evaporator
2. customto remove ethanol
3. additionThen water (250 mL) was added
4. extractionAqueous solution was extracted with ethyl acetate (100 mL)
5. extractionextracted with dichloromethane (3×200 mL) again
6. dry with materialThe combined organic layers were dried over anhydrous magnesium sulfate
7. concentrationconcentrated by rotary evaporator

ORD record

ord-0231aee2920348e49aa297e06ed4cf63

Source dataset

uspto-grants-2012_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08217179B2