Potassium Hydroxide → Fluoroquinolonic acid

Participants

Reaction Steps

3.44 g of 80 percent strength sodium hydride are added in portions to a solution of 31.9 g of ethyl 2-(2,4-dichloro-5-fluoro-benzoyl)-3-cyclopropylaminoacrylate in 300 ml of anhydrous dioxane, while cooling with ice and stirring. The mixture is then stirred at room temperature for 30 minutes and under reflux for 2 hours and the dioxane is stripped off in vacuo. The residue (40.3 g) is suspended in 150 ml of water, 6.65 g of potassium hydroxide are added and the mixture is refluxed for 1.5 hours. The warm solution is filtered and the residue is rinsed with water. The filtrate is then acidified to pH 1-2 with half-concentrated hydrochloric acid, while cooling with ice, and the precipitate is filtered off with suction, washed with water and dried in vacuo at 100° C. 27.7 g of 7-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid of melting point 234°-237° C. are obtained in this manner.

Provenance & Evidence