Methylamine → 3-Ethoxycarbonyl-7,8-difluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine

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Reaction Steps

A solution of methylamine (11.3 g) at approximately 0° C. in ethanol (50 cc) is added in the course of 10 minutes at between 0° and 5° C. to a stirred suspension, maintained at a temperature in the region of 0° C., of ethyl 2-(2-chloro-6,7-difluoro-3-quinolinecarbonyl)-3-(dimethylamino)acrylate (22.3 g) in ethanol (480 cc), the mixture is stirred for 1 hour at between 0° and 5° C., the temperature is allowed to rise to approximately 25° C. and the mixture is stirred for a further 16 hours at the same temperature. The insoluble matter is drained and washed with ethanol (3×100 cc) and ethyl ether (2×100 cc). After 1 recrystallization in dimethylformamide (250 cc), 3-ethoxycarbonyl-7,8-difluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine (16 g) is obtained in the form of a yellow solid, m.p. 323° -324° C.

Provenance & Evidence