2-Amino-4-chlorobenzoic acid → 4-Chloroisatoic anhydride

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 2-amino-4-chloro benzoic acid (10 g, 0.058 mmol) in acetonitrile (60 mL, 1 M), was added pyridine (9.4 mL, 0.117 mmol, 2 equiv), and triphosgene (17.3 g, 0.058 mmol, 1 equiv) in dichloromethane (85 mL, 0.7 M). The orange reaction solution was heated at 50° C. for two hours then cooled to room temperature. The solution was diluted with water (50 mL), and the organic and aqueous layers were separated. The aqueous layer was washed with dichloromethane (3×50 mL), and the combined organic layers were washed once with brine (50 mL), and dried over magnesium sulfate. The solvent was removed in vacuo leaving a yellow solid. The solid was titrated with hexanes to yield 7-chloro-1H-benzo[d][1,3]oxazine-2,4-dione (9.1 g, 74%) as a yellow solid.

Provenance & Evidence