Ethylamine → 8-Chloro-3-ethoxycarbonyl-1-ethyl-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine

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Reaction Steps

16 g of ethylamine are added, in the course of 5 minutes, at between 10° and 15° C., to a stirred suspension of 13.5 g of ethyl 2-(2,7-dichloro-6-fluoroquinoline-3-carbonyl)-3-dimethylaminoacrylate in 135 cm3 of ethanol, the temperature is allowed to rise to about 20° C., 0.5 g of DBU is added and the mixture is heated, with stirring, for 2 hours at a temperature close to 75° C. After cooling to a temperature close to 20° C., the precipitate is drained and washed with twice 100 cm3 of ethanol and twice 100 cm3 of diethyl ether. 10.4 g of 8-chloro-3-ethoxycarbonyl-1-ethyl-7-fluoro-4-oxo-1,4-dihydro-benzo-[b][1,8]naphthyridine are obtained in the form of a yellow solid melting at 300°-301° C.

Provenance & Evidence