Iodoethane → HCID 12816987, compound

Participants

Reaction Steps

Ethyl 7-(4-ethoxycarbonyl-1-piperazinyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate was suspended in dimethylformamide (10 ml) and to the suspension was added potassium carbonate (0.53 g). After the mixture was kept at 60° C. for 10 minutes with stirring, ethyl iodide (1.2 g) was added to the solution. The mixture was stirred for 2 hours at 60°-70° C. The reaction mixture was concentrated to dryness under reduced pressure, and water was added to the residue. After extraction with chloroform, the chloroform extract was dried over anhydrous potassium carbonate. After removal of the chloroform by distillation, the resulting precipitate was recrystallized from a mixture of dichloromethane and n-hexane to give 0.89 g of ethyl 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(4-ethoxycarbonyl-1-piperazinyl)-1,8-naphthyridine-3-carboxylate (mp 171°-173° C.). A mixture of the above ethyl ester (0.8 g), 10% sodium hydroxide (6 ml) and ethanol (2 ml) was refluxed by heating for 3 hours. After cooling, the solution was adjusted to pH 7.0-7.5 with 10% acetic acid. The precipitate was collected by filtration, washed with ethanol and recrystallized from a mixture of dimethylformamide and ethanol to give 0.57 g of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid. m.p. 220°-224° C.

Provenance & Evidence