Water → HCID 20063304, compound

Participants

Reaction Steps

A suspension of 2 g of 3-ethoxycarbonyl-7,8,9-trifluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine in 30 cm3 of dimethyl sulphoxide and 5 g of piperazine is heated at a temperature close to 100° C., with stirring, for 2 hours. The solution obtained at about 100° C. is poured, with stirring, into a mixture of 150 cm3 of water and 50 g of ice. The solution is extracted with 3 times 40 cm3 of trichloromethane. The combined organic phases are extracted with twice 50 cm3 of 0.1 N methanesulphonic acid. 10 g of potassium carbonate are added to the combined aqueous phases. The mixture is extracted with 3 times 40 cm3 of trichloromethane. The combined organic extracts are washed with twice 50 cm3 of water, dried over magnesium sulphate, filtered and concentrated to dryness under reduced pressure (20 kPa) at about 50° C. The residue obtained is recrystallized from 25 cm3 of ethanol. 0.8 g of 3-ethoxycarbonyl-7,9-difluoro-1-methyl-4-oxo-8-(1-piperazinyl)-1,4-dihydrobenzo[b][1,8]naphthyridine is obtained in the form of a yellow solid melting at 221° C.

Provenance & Evidence