Sulfuric Acid → ethyl 7,8,9-trifluoro-1-hydroxymethyl-5-oxo-5H-thiazolo[3,2-a]quinoline-4-carboxylate

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Reaction Steps

Ethyl 2-(3-acetoxy-2-oxopropylthio)-6,7,8-trifluoro-4-hydroxyquinoline-3-carboxylate (3.54 g) was added to concd. sulfuric acid (35 ml) and the mixture was stirred at room temperature for 2 hours and 15 minutes. Thereto water (29 ml) was added gradually with ice-cooling and the mixture was stirred at room temperature for 26 hours, followed by addition of ice-water (400 ml). After precipitated crystal was filtered and washed with water, the resultant was recrystallized from a mixed solvent of chloroform - ethanol to give the title compound (2.38 g) as pale yellow crystals.

Provenance & Evidence