2-Amino-4,5-difluorobenzoic acid, 2,2-dibenzylhydrazide (Example 15) (0.81 g, 2.2 mmol) and triphosgene (0.33 g, 1.1 mmol) are combined in 100 mL of methylene chloride and stirred at 25° C. for 20 hours. The solution is poured into 200 mL of saturated NaHCO3, the layers are separated, and the aqueous layer is washed three times with ethyl acetate. The combined organic layers are dried over magnesium sulfate and then concentrated to give 0.86 g of the title compound as a solid. MS CI: m/z 394 (MH+).
