Water → 7,8,9-Trifluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A suspension of 4 g of 3-ethoxycarbonyl-7,8,9-trifluoro-1-methyl-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine in 30 cm3 of acetic acid and 30 cm3 of 50% hydrochloric acid is heated at a temperature close to 100° C. for 2 hours. After cooling to about 20° C., 100 cm3 of water are added. The precipitate formed is drained, washed with 3 times 50 cm3 of water and recrystallized from 80 cm3 of dimethylformamide. 3.4 g of 7,8,9-trifluoro-1-methyl-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine-3-carboxylic acid are obtained in the form of a colourless solid melting at 350°-352° C.

Provenance & Evidence