Formaldehyde → 1-Cyclopropyl-8-(3,4-dimethyl-1-piperazinyl)-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid

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Reaction Steps

1-Cyclopropyl-8-(3,4-dimethyl-1-piperazinyl)- 7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid is prepared under the conditions of Reference Example 21 but starting from 1.9 g of 1-cyclopropyl-7-fluoro-8-(3-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid, 1.38 cm3 of formic acid and 3.30 cm3 of a 30% aqueous solution of formaldehyde. After recrystallizing crude product from 50 cm3 of ethanol, 1.3 g of 1the cyclopropyl-8-(3,4-dimethyl-1-piperazinyl)-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid are obtained in the form of a yellow solid melting at 219° C.

Provenance & Evidence