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

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Reaction Conditions

Reaction Steps

A suspension of (RS)-8-(3-benzyl-1-piperazinyl)-3-ethoxycarbonyl-7-fluoro-1-methyl-4-oxo-1,4dihydrobenzo[b][1,8]naphthyridine (2.65 g) in N aqueous potassium hydroxide (14 cc) and ethanol (20 cc) is heated to a temperature in the region of 80° C. for 20 minutes, treated at the same temperature with 5% strength acetic acid (32 cc) and stirred for 20 minutes. The insoluble matter is drained at approximately 80° C. and washed with water (2×20 cc), ethanol (2×20 cc) and ethyl ether (2×20 cc). After 2 recrystallizations in dimethylformamide (50 cc each time), (RS)-8-(3-benzyl-1-piperazinyl)-7-fluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid (2.05 g) is obtained in the form of a yellow solid, decomposing at 270°-275° C.

Provenance & Evidence