1-Methylpiperazine → 6,8-Difluoro-1-(formylmethylamino)-7-(4-methylpiperazin-1-YL)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid ethyl ester

Beteiligte Stoffe

Reaktionsschritte

A suspension of 4.92 g (15 mmol) of 3-(2-formyl-2-methylhydrazino)-2-(2,3,4,5-tetrafluorobenzoyl)acrylic acid ethyl ester and 3.41 ml (30.1 mmol) of N-methyl-piperazine in 15 ml of toluene were heated at reflux for 7.5 hours after which a clear, yellow solution was formed. After the addition of further 2.08 ml of N-methyl-piperazine the mixture was heated for 2 hours, cooled and evaporated at 49° C./130 torr. The yellowish oil (13.7 g) was taken up in 30 ml of dichloromethane, washed with 50 ml of water and subsequently twice with each 7.5 ml of half-saturated brine. The aqueous extracts were washed twice with each 15 ml of dichlormethane, the organic phases united, dried over magnesium sulphate, filtered and evaporated at 47° C./20 torr. The crystalline, beige residue (6.1 g) was suspended in 40 ml of tert.-butylmethyl ether, vigorously digested for 50 min., the crystals filtered, washed twice with each 10 ml of tert.-butylmethyl ether and dried at 45° C./13 torr. 5.41 g (88%) of 6,8-difluoro-1,4-dihydro-1-(N-methylformamido)7-(4-methyl- 1-piperazinyl)-4-oxo-3-quinoline-carboxylic acid ethyl ester were obtained as beige crystals of mp 180° C.

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