Chloroacetyl chloride → 7,8-Difluoro-6-methoxycarbonyl-4H-benzo[1,4]oxazine-3-one

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Reaction Steps

A mixture of 5-amino-2,3-difluoro-4-hydroxy-benzoic acid methyl ester (5.5 g, 27.1 mmol) and benzyl-triethylammonium chloride (6.2 g) in chloroform (300 mL) was warmed and sonicated until most of the solid was dissolved. The mixture was cooled in an ice bath and sodium hydrogen carbonate (10 g) was added, followed by chloroacetyl chloride (2.4 mL, 29 mmol). The combined mixture was stirred in cold for 1 hour and then under reflux for approximately 9 hours. It was then evaporated in vacuo and the resulting residue was treated with water and chloroform to give a solid. This solid was collected by filtration, washed with water, diethyl ether and dried in vacuo to give the title compound (3.7 g, 56%).

Provenance & Evidence