Hydrochloric Acid → 1-(6-Methoxy-3-pyridazinyl)-5-(2-pyridyl)pyrazole-3-carboxylic acid

Participants

Reaction Steps

1-(6-Methoxy-3-pyridazinyl)-5-(2-pyridyl)pyrazole-3-carboxylic acid methyl ester (2.20 g) obtained in Method B step 3) of Referential Example 139 was dissolved in a solvent mixture of methanol (30 mL) and tetrahydrofuran (30 mL), and 1N aqueous sodium hydroxide (15 mL) was added to the solution at room temperature, followed by stirring for 2.5 hours. Under cooling with ice, 1N aqueous hydrochloric acid (15 mL) and a solvent mixture of chloroform-methanol (10:1) were added to the reaction mixture for partitioning the mixture. The organic layer was dried over sodium sulfate anhydrate, followed by filtration. The solvent was removed under reduced pressure, and isopropyl ether was added to the residue, and then the precipitated solid was recovered by filtration, to thereby give the title compound (1.42 g, 47.6%).

Provenance & Evidence