Sodium Bicarbonate → 8-bromo-4-hydroxy-5-methoxy-3-Quinolinecarboxylic acid ethyl ester

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Reaction Steps

2-[(2-Bromo-5-methoxy-phenylamino)-methylene]-malonic acid diethyl ester (9 g, 24.2 mmol) was slowly added to polyphosphoric acid (30 g) at 120° C. The mixture was stirred at this temperature for additional 30 min and then cooled to room temperature. Absolute ethanol (30 mL) was added and the resulting mixture was refluxed for 30 min. The mixture was basified with aqueous sodium bicarbonate at 25° C. and extracted with EtOAc (4×100 mL). The organic layers were combined, dried and the solvent evaporated to give 8-bromo-5-methoxy-4-oxo-1,4-dihydro-quinoline-3-carboxylic acid ethyl ester (2.3 g, 30%).

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