Hydrochloric Acid → 2-(5-chloro-4-hydroxy-6-oxo-6H-pyridazin-1-yl)-3-cyclopentyl-propionic acid

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Reaction Steps

A solution of 3-cyclopentyl-2-(4,5-dichloro-6-oxo-6H-pyridazin-1-yl)-propionic acid methyl ester (Intermediate 79 step 1, 18.0 g, 56.4 mmol) in a 4N aqueous sodium hydroxide solution (140 mL) was stirred at 60° C. overnight. The reaction solution was acidified with a 6N aqueous hydrochloric acid solution to pH=2˜3. Ethyl acetate was added to the solution and was stirred for 10 min. The aqueous phase was extracted with ethyl acetate, the combined organics were washed with a saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. The residue was washed with diethyl ether (50 mL) to afford 2-(5-chloro-4-hydroxy-6-oxo-6H-pyridazin-1-yl)-3-cyclopentyl-propionic acid as a white solid (14.5 g, 90%).

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