Formic Acid → N-Methyl Gatifloxacin HCl

Participants

Reaction Steps

A solution of 1.5 g (0.004 mole) of 1-cyclopropyl-6-fluoro-8-methoxy-7-(3-methyl-1-piperazinyl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid (free form) (prepared as described in Example 22, but omitting the final reaction with hydrochloric acid) in a mixture of 75 ml of 90% aqueous formic acid and 45 ml of 37% aqueous formaldehyde was heated under reflux for 15 hours. 8 ml of concentrated hydrochloric acid were then added to the reaction mixture, and the solvent (formic acid, formalin and water) was then removed by evaporation under reduced pressure. Methanol was then added to the residue, and the resulting solution was filtered to remove insoluble material. The filtrate was evaporated to dryness under reduced pressure, and the residue was washed with ethanol to afford 1.35 g of 1-cyclopropyl-6-fluoro-8-methoxy-7-(3,4-dimethyl-1-piperazinyl)-1,4-dihydro-4-oxoquinoline-3-carboxylic acid hydrochloride as a colorless powder melting at 218°-221° C. (with decomposition).

Provenance & Evidence