3-Acetoxy-5,5-difluoro-6-oxo-5,6-dihydro-quinoline-4-carboxylic acid methyl ester → 3-Acetoxy-5-fluoro-6-hydroxy-quinoline-4-carboxylic acid methyl ester

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Reaction Steps

10% Palladium on activated carbon (178 mg, 0.17 mmol, 0.015 eq) is added at room temperature to a stirred solution of 3-acetoxy-5,5-difluoro-6-oxo-5,6-dihydro-quinoline-4-carboxylic acid methyl ester (2.27 g, 11.32 mmol, 1.0 eq) in methanol (50 mL). The resulting mixture is stirred under hydrogen flow (1 bar) at room temperature for 2 hours. The catalyst is then removed by filtration and the solution is concentrated to afford 3-acetoxy-5-fluoro-6-hydroxy-quinoline-4-carboxylic acid methyl ester as a light yellow semisolid (2.03 g, 95% yield) which is directly engaged in the next step.

Provenance & Evidence