Piperazine → Ethyl norfloxacin

Participants

Reaction Conditions

Reaction Steps

A mixture of 18 ml of triethylamine, 10.3 g of anhydrous piperazine, and 8.9 g of 1-ethyl-6-fluoro-7-chloro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid ethyl ester was refluxed with stirring for 20 hrs. The reaction mixture was concentrated under reduced pressure, 30 ml of chloroform was added to the residue, and cooled at 0° C. to give crystals. The crystals were filtered to recover 2 g of 1-ethyl-6-fluoro-7-chloro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid ethyl ester. The above filtrated solution was extracted with diluted hydrochloric acid, the hydrochloric acid layer was neutralized with diluted sodium hydroxide solution, and the neutralized solution was extracted with chloroform. The chloroform layer was washed with water and dried over anhydrous magnesium sulfate, the chloroform was evaporated under reduced pressure. The residue was treated by the same procedure in Example 1 to give 7.4 g (71% yield) of 1-ethyl-6-fluoro-7-(1-piperazinyl)-4-oxo-1,4-dihydroquinoline-3-carboxylic acid ethyl ester. mp: 178°- 180° C.

Provenance & Evidence