In 58 ml of ethanol was suspended 1.46 g of ethyl 8-acetoxymethyl-7-bromo-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylate, and 19 mg of sodium methoxide was added to the suspension, after which the resulting mixture was stirred at room temperature for seven hours. To the reaction mixture was added 60 ml of water and the pH was adjusted to 7 with 1N hydrochloric acid, after which the crystals formed were collected by filtration, to obtain 1.28 g of colorless, crystalline ethyl 7-bromo-1-cyclopropyl-6-fluoro-8-hydroxymethyl-1,4-dihydro-4-oxoquinoline-3-carboxylate.
