Acetic Anhydride → 5-Chloro-2-(3-fluorophenyl)-4H-3,1-benzoxazin-4-one

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Reaction Steps

29 parts of N-(3'-fluorobenzoyl)-6-chloroanthranilic acid in 250 parts of acetic anhydride are stirred under reflux for 21/2 hours. The mixture is evaporated down under reduced pressure, the residue is taken up in methylene chloride and this solution is washed with twice 100 parts by volume of 0.5 N sodium hydroxide solution and then with water. Thereafter, the solution is chromatographed on neutral alumina, giving 23.6 parts of 2-(3'-fluorophenyl)-5-chloro-4H-3,1-benzoxazin-4-one, of melting point 123°-125° C.; yield: 86.7% of theory.

Provenance & Evidence