1-Methylpiperazine → HCID 14700561, compound

Participants

Reaction Steps

7-Fluoro-1-methyl-8-(4-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid is prepared under conditions analogous to Reference Example 1 but starting from 5 g of 8-chloro-7-fluoro-1-methyl-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid and 16 g of 1-methylpiperazine in 50 cm3 of pyridine. After concentrating the reaction mixture under reduced pressure, 25 cm3 of acetic acid are added to the residue, which is suspended in 100 cm3 of water. A very small amount of insoluble matter is removed by filtration through diatomaceous silica for filtration. 200 cm3 of 3N aqueous potassium hydroxide solution are added to the filtrate and a very small amount of insoluble matter is again removed by filtration through diatomaceous silica for filtration. 5 cm3 of acetic acid are added to the filtrate. The precipitate formed is drained and washed with 3 times 50 cm3 of water. After recrystallizing twice from 17 cm3 of dimethylformamide each time, 3.2 g of 7-fluoro-1-methyl-8-(4-methyl-1-piperazinyl)-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid are obtained in the form of a yellow solid melting at 356° C.

Provenance & Evidence