Sodium hydride → Fluoroquinolonic acid

Participants

Reaction Steps

3.44 g of 80% sodium hydride are added in portions, with cooling in ice and stirring, to a solution of 31.9 g of ethyl 2-(2,4-dichloro-5-fluorobenzoyl)-3-cyclopropylaminoacrylate (6) in 100 ml of anhydrous dioxane. The mixture is then stirred at room temperature for 30 minutes and under reflux for 2 hours and the dioxane is removed 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 h. The warm solution is filtered and washed with H2O. The solution is then acidified to pH 1 to 2 with half-concentrated hydrochloric acid, cooling in ice, the precipitate is filtered off with suction, washed with water and dried in vacuo at 100° C. In this manner, 27.7 g of 7-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid VII, of melting point 234°-237° C., are obtained.

Provenance & Evidence