Acetic Acid → 5-amino-7-fluoro-1-[2-(S)-fluoro-1-(R)-cyclopropyl]-1,4-dihydro-8-methoxy-4-oxoquinoline-3-Carboxylic Acid

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Reaction Steps

A mixture of ethyl 5-amino-7-fluoro-1-[2-(S)-fluoro-1-(R)-cyclopropyl]-1,4-dihydro-8-methoxy-4-oxoquinoline-3-carboxylate (2.68 g, 7.92 mmol), acetic acid (20 ml) and concentrated hydrochloric acid (20 ml) was heated under reflux for 3 hours. After cooling there action solution with ice, water (200 ml) was poured therein and the precipitated crystals were filtered out. After washing with excess water, a small amount of cold ethanol and excess diethyl ether in that order, the crude crystals obtained were purified by recrystallization in a mixed solvent of chloroform/methanol and then dried under a reduced pressure. 1.26 g (51%) of the title compound was thereby obtained in the form of yellow crystals.

Provenance & Evidence