Hydrochloric Acid → 5-(Benzyloxy)-4-oxo-1,4-dihydropyridine-2-carboxylic acid

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Reaction Steps

300 g (1.22 mol) of 4-oxo-5-(phenylmethoxy)-4H-pyran-2-carboxylic acid was put into a flask and 5 l of 33% ammonium hydroxide was carefully added with stirring. The reaction mixture was then stirred under reflux. After 3 hours, one additional liter of 33% ammonium hydroxide was added slowly. Stirring was continued for further 2 hours under reflux. The reaction solution was then evaporated until the product crystallized. The product was transferred back into the reaction flask and water added until a clear solution was obtained (approximately 5 l, pH 6.38). This solution was stirred vigorously while concentrated hydrochloric acid was added dropwise until a pH of 3 was obtained. The precipitated white product was removed by filtration, thoroughly washed with water and dried. Yield: 273 g.

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