6-(4-Bromo-2-chloro-phenylamino)-7-chloro-3-methyl-3H-benzoimidazole-5-carboxylic acid 10ff (32 mg, 0.077 mmol), O-(2-vinyloxy-ethyl)-hydroxylamine (0.010 mL, 0.092 mmol), HOBt (13 mg, 0.093 mmol), triethylamine (0.011 mL, 0.077 mmol), and EDCI (19 mg, 0.10 mmol) are dissolved into dimethylformamide (1.0 mL) and allowed to stir under a nitrogen atmosphere at room temperature for 24 hours. The reaction mixture is diluted with EtOAc, washed with water (3×), 10% potassium carbonate (2×), saturated ammonium chloride, brine, dried (Na2SO4), and concentrated under reduced pressure to give 39 mg of 85% pure material. MS APCI (−) m/z 497, 501 (M−, Br pattern) detected.
