Methane → 1-Ethyl-6,8-difluoro-1,4-dihydro-4-oxo-7-[3-(4-acetamidobenzenesulfonamido)-1-pyrrolidinyl]-3-quinolinecarboxylic acid

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Reaction Steps

2.80 g of 1-ethyl-6,8-difluoro-1,4-dihydro-4-oxo-7-(3-amino-1-pyrrolidinyl)-3-quinolinecarboxylic acid (see REFERENCE SYNTHESIS EXAMPLE hereinafter) is suspended in 100 ml of pyridine. To this is slowly added 3.88 g of 4-acetamidobenzenesulfonyl chloride in 20 ml of benzene. The mixture is stirred for 1 hour under ice-cooling and then overnight at room temperature. After evaporating off the solvent from the reaction mixture, the residue is added water and then adjusted to pH 12 with 2N sodium hydroxide solution. Any undissolved matter, if present, is filtered off. The filtrate is adjusted to pH 7 with acetic acid. The precipitated crystals are collected by filtration and washed. The crystals are then suspended in 100 ml of water. The suspension is adjusted to pH 4 with acetic acid, stirred and then filtered to recover the crystals, which are then thoroughly washed with water. The crude crystals thus obtained are dissolved in dimethylformamide (DMF), treated with activated charcoal, and recrystallized from DMF-methanol to give 1.45 g of the titled compound.

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