Formaldehyde → 7-(3,4-Dimethyl-1-piperazinyl)-1-ethyl-6,8-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxlic acid

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Reaction Steps

A mixture of 1.40 g of 1-ethyl-6,8-difluoro-1,4-dihydro-7-(3-methyl-1-piperazinyl)-4-oxoquinoline-3-carboxylic acid, 2.8 ml of 90% formic acid and 2.2 ml of 37% formalin was heated for 4 hours under reflux. The reaction mixture was evaporated and the residue was dissolved in water. The solution was neutralized with aqueous sodium bicarbonate. The precipitate was filtered and recrystallized from ethanol to give 0.32 g of the title compound as colorless needles, M.p. 211.5°-212° C.

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