Ethanol → 8-bromo-7-fluoro-5-oxo-1,2-dihydro-5H-thiazolo(3,2-a) quinoline-4-carboxylic acid

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Reaction Steps

Then 1.0 gram of the fractioned ethyl 8-bromo-7-fluoro-5-oxo-1,2-dihydro-5H-thiazolo(3,2-a)-quinoline-4-carboxylate was suspended in a solution of 2.0 grams of sodium hydroxide (0.05 mmol), 50 ml of water and 20 ml of ethanol, the mixture was heated to reflux for four hours, the transparent solution was acidified with acetic acid after being cooled, crystals separated out were collected by filtration, washed with water, and dried. Thus, 860 mg (93.5 percent) of the title compound was obtained. Colorless powdery crystals were then recrystallized from dimethyl formamide. Melting point was 228° to 290° C. (decomposition).

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