1-(4-Fluorophenyl)piperazine → Ethyl 9-fluoro-8-[4-(4-fluorophenyl)piperazin-1-yl]-4-methyl-1-oxo-1,4-dihydrobenzo[f] [1,7]naphthyridine-2-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A suspension of 1.5 g of ethyl 8,9-difluoro-4-methyl-1-oxo-1,4-dihydrobenzo[f][1,7]naphthyridine-2-carboxylate and 1.7 g of 1-(4-fluorophenyl)piperazine in 30 cm3 of dimethyl sulphoxide was heated, with stirring, at a temperature of 90° C. for 4 days. After cooling to 20° C., the mixture was poured into 150 cm3 of ice-cold water. The medium was extracted 3 times with 150 cm3 of dichloromethane. The organic extracts were washed 3 times with 100 cm3 of water and dried over sodium sulphate. After filtration and concentration under reduced pressure (5.2 kPa), the compound obtained was purified by chromatography on silica gel (0.06-0.20 mm). Elution was carried out with 7.8 liters of a dichloromethane-ethanol mixture (97-3 by volume), and 200 cm3 fractions were collected. The fractions between 5.6 and 7.8 liters were concentrated under reduced pressure (5.2 kPa). 0.77 g of ethyl 9-fluoro-8-[4-(4-fluorophenyl)piperazin-1-yl]-4-methyl-1-oxo-1,4-dihydrobenzo[f][1,7]naphthyridine-2-carboxylate was obtained in the form of yellow crystals, which melted at 300° C.

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