Hydrochloric Acid → 1-Cyclopropyl-5-methyl-6,7,8-trifluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid

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Reaction Steps

To ethyl 1-cyclopropyl-6,7,8-trifluoro-5-methyl-1,4-dihydro-4-oxoquinoline-3-carboxylate (4.10 g) are added 90% acetic acid--conc. hydrochloric acid (4 : 1, 81.25 ml) and the mixture is refluxed for 2 hours. After cooling, the precipitated crystals are isolated, washed with water, ethanol, and diethyl ether in this order to give 1-cyclopropyl-6,7,8-trifluoro-5-methyl-1,4,-dihydro-4 -oxoquinoline-3-carboxylic acid (3.47 g), as white needles, m.p. 218°-220° C.

Provenance & Evidence