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

Participants

Reaction Conditions

Reaction Steps

A mixture of 6-fluoro-1-(2-fluoroethyl)-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid (3.0 g), 37% formalin (4 ml) and formic acid (9 ml) is heated at 110° C. for 16 hours with stirring. The reaction mixture is concentrated to dryness under reduced pressure. The residue is dissolved in 10% aqueous ammonia, treated with active charcoal, and filtered. The filtrate is adjusted to pH 8-8.5 with 10% hydrochloric acid. The precipitate is collected by filtration, and recrystallized from acetonitrile to give 2.67 g of 6-fluoro-1-(2-fluoroethyl)-1,4-dihydro-7-(4-methyl-1-piperazinyl)-4-oxo-1,8-naphthyridine-3-carboxylic acid (compound 1), m.p. 224°-226° C.

Provenance & Evidence