Triethylamine → (RS)-7-fluoro-1-methyl-4-oxo-8-(3-phenyl-1-piperazinyl)-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid

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Reaction Conditions

Reaction Steps

A suspension of 8-chloro-7-fluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid (1.84 g) in pyridine (20 cc), (RS)-2-phenylpiperazine (5.83 g) and triethylamine (1.24 g) is heated to a temperature in the region of 115° C. for 5 hours. After cooling to approximately 20° C., the precipitate formed is drained and washed with pyridine (2×5 cc), isopropyl alcohol (2×5 cc), ethanol (2×5 cc) and ethyl ether (1×20 cc). After 1 recrystallization in a mixture of dimethylformamide (40 cc) and ethanol (40 cc), (RS)-7-fluoro-1-methyl-4-oxo-8-(3-phenyl-1-piperazinyl)-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid (0.920 g) is obtained in the form of a yellow solid, m.p. 265° C.

Provenance & Evidence