1-Methylpiperazine → 1-Ethyl-7-fluoro-8-(4-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid

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Reaction Steps

1-Ethyl-7-fluoro-8-(4-methyl-1-piperazinyl)-4-oxo- 1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid is prepared under the conditions of Example 5 but starting from 1.6 g of 8-chloro-1-ethyl-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid and 4.5 g of 4-methylpiperazine in 16 cm3 of pyridine. After recrystallizing 4 times from, in total, 120 cm3 of dimethylformamide, 1.2 g of 1-ethyl-7-fluoro-8-(4-methyl-1-piperazinyl)-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid are obtained in the form of a yellow solid melting at 285°-286° C. solvated with 1% of water.

Provenance & Evidence