Acetic Acid → 1-Cyclopropyl-7-fluoro-8-(4-methyl-1-piperazinyl)-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid

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Reaction Steps

A suspension of 0.85 g of 1-cyclopropyl-3-ethoxycarbonyl-7-fluoro-8-(4-methyl-1-pip-erazinyl)-4 -oxo-1,4-dihydro-benzo[b][1,8]naphthyridine in 12 cm3 of ethanol, 5 cm3 of 2 N aqueous potassium hydroxide solution and 7 cm3 of water is heated at a temperature close to 80° C. for 1 hour. After adding 5.8 cm3 of a 10% aqueous solution of acetic acid, the precipitate obtained is drained and washed with 3 times 5 cm3 of water. After recrystallizing twice from a mixture of 7.5 cm3 of ethanol and 7.5 cm3 of dimethylformamide each time, 0.4 g of 1-cyclopropyl-7-fluoro-8-(4-methyl-1-piperazinyl)-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid is obtained in the form of a yellow solid melting at 250° C.

Provenance & Evidence