O-Benzyl or O-Bn

Protection

To a mixture of 6-fluoro-4-hydroxy-naphthalene-2-carboxylic acid methyl ester (4.6g, 21 mmol) and potassium carbonate (5.8g, 42 mmol), was added benzyl bromide (5.47 mL, 32 mmol) in acetone (100 mL). After being stirred vigorously at reflux for 4 hours under a nitrogen atmosphere, the resulting mixture was cooled to rrom temperature, filtered and concentrated in vacuo to give 4-benzyloxy-6-fluoro-naphthalene-2-carboxylic acid methyl ester (5.85g, 90%) as a white solid. 

Patent reference: WO2010055006

 

Deprotection

To a solution of O-Bn protective compound (3.4 g, 10.0 mmol) in methanol (50 ml) was added 10 % palladium on carbon (0.5g). The resulting mixture was vigorously stirred under a hydrogen (balloon) atmosphere overnight, and then filtered. The filtrate was concentrated in vacuo to give the title compound (2.44g, 98%) as a white solid. 

Patent reference: WO2010055006

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