Formic acetic anhydride was prepared by adding 96% formic acid (0.702 ml, 18.3 mmol) to acetic anhydride (0.863 ml, 9.1 mmol) and stirring for 30 minutes. A tetrahydrofuran solution of diisopropylethylamine (3.2 ml, 18.3 mmol) and 4-{[4-(1,3-dioxolan-2-yl)-2-(methyloxy) phenyl]oxy}-2-nitroaniline (2.53 g, 7.62 mmol) was added to the formic acetic anhydride. The reaction was stirred for approximately 18 hours. The reaction mixture was diluted with ethyl acetate and washed with 1N NaOH. The organic layers were dried over MgSO4 and concentrated. The residue was purified by silica gel column chromatography to give (4-{[4-(1,3-dioxolan-2-yl)-2-(methyloxy)phenyl]oxy}-2-nitrophenyl) formamide. (M+1) 360.8, 2.31 min (LC/MS method B)
