Dimethyl Sulfoxide → 7-[(2,3-Difluorobenzyl)oxy]-2,5-dimethylpyrazolo[1,5-a]pyridine-3-carboxylic Acid

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Reaction Conditions

Reaction Steps

A solution of 190 mg (0.527 mmol) of 7-[(2,3-difluorobenzyl)oxy]-2,5-dimethylpyrazolo[1,5-a]pyridine-3-carboxylic acid ethyl ester from Example 116A in 5 ml of dioxane was admixed with 2.1 ml of 2 N sodium hydroxide solution. The resulting mixture was stirred at 90° C. for 15 h. Owing to incomplete mixing, 1 ml of dimethyl sulphoxide was added, followed by further 2 N sodium hydroxide solution (1 ml). The resulting mixture was stirred for a further 2 h. After the reaction had ended, the solvent was removed under reduced pressure. The residue was admixed with acetonitrile (5 ml), followed by the dropwise addition of trifluoroacetic acid (2 ml). The resulting precipitate was filtered off and dried under reduced pressure, which gave 130 mg (71% of theory, 93% pure) of the target compound.

Provenance & Evidence