Water → (RS)-7-Fluoro-8-[3-(2-furyl)-1-piperazinyl]-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A suspension of (RS)-3-ethoxycarbonyl-7-fluoro-8-[3-(2-furyl)-1-piperazinyl]-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine (1.3 g) in 0.5 N aqueous potassium hydroxide (12 cc) and ethanol (12 cc) is heated for 1 hour to a temperature in the region of 80° C. and then treated at the same temperature with an N aqueous solution (6 cc) of methanesulphonic acid. After cooling to approximately 20° C., the insoluble water is drained, washed with water (3×10 cc), ethanol (3×10 cc) and ethyl ether (3×10 cc) and recrystallized in a mixture of ethanol (13 cc) and dimethylformamide (27 cc). (RS)-7-Fluoro-8-[3-(2-furyl)-1-piperazinyl]-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid (0.570 g) obtained in the form of a yellow solid, m.p. 258°-260° C.

Provenance & Evidence