Methanol → 3-bromo-1-(3,5-dichloropyridin-2-yl)-1H-pyrazole-5-carboxylic acid

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Reaction Steps

To a 100 mL flask, ethyl 3-bromo-1-(3,5-dichloropyridin-2-yl)-1H-pyrazole-5-carboxylate (2.0 g, 5.5 mmol), methanol (10 mL), water (10 mL) and sodium hydroxide (0.3 g, 5.5 mmol) were added. After being stirred at room temperature for 1 hour, the mixture reacted completely. The reaction mixture was concentrated by rotary evaporator to about 10 mL as a dark brown solution. Then water (40 mL) was added into the dark brown solution. The aqueous solution was extracted with ethyl ether (50 mL) and acidified with concentrated hydrochloric acid to pH of 4. The precipitate was isolated by filtration, washed with water (2×50 mL) and dried to give the product (0.97 g) as white solid in 48% yield.

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