Dimethyl Sulfoxide → 7-(2-Chloro-6-fluorobenzyloxy)-2,5-dimethylpyrazolo[1,5-a]pyridine-3-carboxylic Acid

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Reaction Conditions

Reaction Steps

A solution of 198 mg (0.62 mmol) of 7-(2-chloro-6-fluorobenzyloxy)-2,5-dimethylpyrazolo[1,5-a]pyridine-3-carboxylic acid ethyl ester (Example 136A) in 6.7 ml of 1,4-dioxane was admixed with 2 M sodium hydroxide solution (2.5 ml). The mixture was stirred at 90° C. for a further 18 hours. The reaction mixture was admixed with 0.8 ml of dimethyl sulphoxide and stirred at 90° C. for a further 6 hours. The reaction mixture was concentrated under reduced pressure. The residue was admixed with acetonitrile (5 ml) and trifluoroacetic acid (0.8 ml), and then with water and dichloromethane. The organic phase was removed and concentrated under reduced pressure. The residue was purified by flash chromatography using a prepacked silica gel cartridge (mobile phase: dichloromethane/methanol, gradient 80% to 100%), which gave 105 mg (27% yield, 56% pure) of the target compound, which was used in the next step without further purification.

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