Acetic Acid → 1-Ethyl-7-fluoro-8-[4-(4-fluorophenyl)piperazin-1-yl]-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid

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Reaction Steps

1-Ethyl-7-fluoro-8-[4-(4-fluorophenyl)piperazin-1-yl]-4-oxo-1,4-dihydrobenzo-[b][1,8]naphthyridine-3-carboxylic acid was prepared under the conditions of Example 2, but from 1.75 g of 8-chloro-1-ethyl-7-fluoro-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid and 3.6 g of 4-(4-fluorophenyl)piperazine in 18 cm3 of pyridine. The solid obtained was taken up in 10 cm3 of water and 1.9 cm3 of 10% acetic acid were added. The suspension was brought to approximately 100° C. The solidified product was filtered off and washed 2 times with 10 cm3 of water and 2 times with 10 cm3 of warm ethanol. After recrystallizing twice from 25 cm3 of dimethylformamide on each occasion, 1.7 g of 1-ethyl-7-fluoro-8-[4-(4-fluorophenyl)piperazin-1-yl]-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid were obtained in the form of a pinkish-beige solid melting at about 311-312° C.

Provenance & Evidence