Diphosgene → Isopropyl 2-chloro-4-fluoro-5-isocyanatobenzoate

5.4 ml (0.045 mol) of trichloromethyl chloroformate were added to 30 ml of ethyl acetate. The resulting solution was cooled to 0° C. A solution of 13.9 g (0.06 mol) of 4-chloro-2-fluoro-5-isopropoxycarbonylaniline in 25 ml of ethyl acetate were added dropwise to the above cooled solution over a period of 15 minutes. The mixture was stirred at a temperature of 0° to 10° C. for an hour, and then refluxed for two hours. The reaction mixture was concentrated to give 15.45 g (yield 99.9%) of the desired product as nearly white crystals with a melting point of 41°-43° C.