Acetic Anhydride → 1-Cyclopropyl-6,7,8-trifluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To 17.6 g (66.6 mmol) of the 2,3,4,5-tetrafluoro-β-oxo-benzenepropanoic acid was added 14.6 g (~1.5 equivalents) of triethylorthoformate and 16.19 g (2.38 equivalents) of acetic anhydride. The mixture was refluxed for two hours at 120° (and was then cooled to 80° C. and concentrated in vacuo. The mixture was diluted with t-butanol, cooled to 10° C., and 3.8 g (1.05 equivalents) of cyclopropylamine in 120 ml of t-butanol was added. The mixture was stirred at 20° C., for 30 minutes and then warmed to 50° C. overnight. At this temperature 7.5 g of potassium t-butoxide was added in 50 ml of t-butanol and the mixture was stirred for four hours. It was filtered and the solids dissolved in 250 ml of hot acetic acid and 200 ml of 3N hydrochloric acid was added in portions over four hours at 100° C. The mixture was cooled and the solids collected to give 15.44 g (82%) of the 1-cyclopropyl-6,7,8-trifluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid, mp 226°-228° C.

Provenance & Evidence