Ethanol → 1,8-Naphthyridine-3-carboxylic acid, 1,4-dihydro-6-fluoro-1-(2-fluoroethyl)-4-oxo-7-(1-piperazinyl)-

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Reaction Steps

A suspension of the above ester (4.8 g) in 10% hydrochloric acid (48 ml) is heated for 2 hours on a steam-bath. After cooling, an appropriate amount of ethanol is added to the mixture to precipitate crystals, which are collected by filtration, dissolved in water (about 50 ml), treated with active charcoal, and filtered. The filtrate is adjusted to pH 7.5-8 with 10% aqueous ammonia to give 3.5 g of 6-fluoro-1-(2-fluoroethyl)-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid (m.p. 223°-225° C.).

Provenance & Evidence