Acetic Acid → 1,8-naphthyridine-3-carboxylic Acid

Participants

Reaction Conditions

Reaction Steps

A suspension of 4 g of 7,8,9-trifluoro-1-methyl-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid in 60 cm3 of dimethyl sulphoxide and 3 g of 1-methylpiperazine is heated at 80° C. for 1 hour and a half. After cooling to about 20° C., 150 cm3 of water are added. 18 cm3 of 10% acetic acid are added to the solution obtained. The precipitate formed is drained, washed with 3 times 50 cm3 of water and recrystallized from 50 cm3 of dimethylformamide. 4 g of 7,9-difluoro-1-methyl-8-(4-methyl-1-pip-erazinyl)-4-oxo-1,4-dihydrobenzo[b]1,8]naphthyridine-3-carboxylic acid are obtained in the form of a yellow solid melting at 316° C..

Provenance & Evidence