5-Bromo-4-(2-chloro-4-fluorophenyl)-1,3-dimethyl-1H-pyrazole (i.e. the product of Step B) (0.20 g, 0.66 mmol), palladium(II) acetate (15 mg, 0.066 mmol), 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (76 mg, 0.13 mmol) and powdered potassium carbonate (1.8 g, 13 mmol) were combined in anhydrous 1,4-dioxane (3 mL), and the mixture was sparged with a subsurface stream of N2 gas for 10 min. 2,6-Difluoro-4-methoxyaniline (0.22 g, 1.3 mmol) was added in one portion, and the reaction mixture was heated at reflux for 22 h. The reaction mixture was filtered through Celite® diatomaceous filter aid, and the filter pad was washed with ethyl acetate (20 mL). The filtrate was washed with water (10 mL) and brine (10 mL), dried over MgSO4, and concentrated to leave a semisolid residue. This residue was purified by column chromatography through 5 g of silica gel eluted with a gradient of hexanes/ethyl acetate (20:1 to 1:3) to give the title compound as a light-brown solid (48 mg).
