Hydrochloric Acid → 4-(1-cyclopentyl-4-oxo-4,5-dihydro-1H-pyrazolo[4,3-c]pyridin-3-yl)thiophene-2-carboxylic acid

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Reaction Steps

To a solution of methyl 4-(1-cyclopentyl-4-oxo-4,5-dihydro-1H-pyrazolo[4,3-c]pyridin-3-yl)thiophene-2-carboxylate (97 mg) obtained in Step E of Example 12 in a mixed solvent of THF (10 mL)/methanol (10 mL) was added 1N aqueous sodium hydroxide solution (2 mL) under ice-cooling, and the mixture was stirred at room temperature for 96 hr. To the reaction mixture was added 1N hydrochloric acid (2 mL) under ice-cooling, and the mixture was stirred, and extracted twice with ethyl acetate. The combined organic layers were washed with saturated brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure to give the title compound (83 mg).

Provenance & Evidence