Formaldehyde → HCID 14700579, compound

Participants

Reaction Steps

A solution of 1.15 g of 7-fluoro-1-methyl-8-(3-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid in 1.35 cm3 of 98% formic acid and 3.25 cm3 of a 30% aqueous formaldehyde solution is heated at a temperature close to 100° C. for 2 hours. The reaction mixture is concentrated under reduced pressure (20 kPa) at 50° C. and 5 cm3 of water are then added, the solution obtained is brought to pH 7 by adding 0.5 cm3 of 2 N aqueous potassium hydroxide solution and heated at a temperature close to 100° C. for 2 minutes. The product, which crystallizes, is drained at 20° C. and washed with twice 10 cm3 of water. The crude product obtained is recrystallized twice from 10 cm3 dimethylformamide each time. 0.55 g of 8-(3,4-dimethyl-1-piperazinyl)-7-fluoro-1-methyl-4-oxo-1,4-dihydro-benzo [b][1,8]-naphthyridine-3-carboxylic acid is obtained in the form of a yellow solid melting at 306°-308° C.

Provenance & Evidence