Ethyl 6-bromo-2-quinoxalinecarboxylate (0.108 g, 0.384 mmol), 3-(2,6-dichlorophenyl)-5-(1-methylethyl)-4-({[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]oxy}methyl)isoxazole (0.27 g, 0.553 mmol), potassium phosphate (0.256 g, 1.21 mmol), palladium(II)acetate (0.0088 g, 0.039 mmol), triphenylphosphine (0.013 g, 0.050 mmol), 1,4-dioxane (8 mL) and water (0.035 mL) were combined and heated at 60° C. with stirring overnight. After 20 hours, the reaction mixture was allowed to stand at room temperature. The reaction mixture was partitioned between water and ethyl acetate. The aqueous phase was separated and extracted a second time with ethyl acetate. The organic extracts were combined, washed with brine, dried over magnesium sulfate, filtered, and the filtrate was concentrated to give an oil. The crude product was purified by flash chromatography over silica with hexanes:ethyl acetate (100:0 to 50:50) to give a yellow solid. The solid was dissolved in dichloromethane and the solution was concentrated to give 0.12 g (56%) of ethyl 6-[4-({[3-(2,6-dichlorophenyl)-5-(1-methylethyl)-4-isoxazolyl]methyl}oxy)phenyl]-2-quinoxalinecarboxylate as a yellow amorphous solid. 1H NMR (CDCl3, 400 MHz): δ 9.52 (s, 1H), 8.31 (d, J=9 Hz, 1H), 8.27 (d, J=2 Hz, 1H), 8.06 (dd, J=9, 2 Hz, 1H), 7.65 (d, J=9 Hz, 2H), 7.41 (m, 2H), 7.32 (dd, J=9, 7 Hz, 1H), 6.92 (d, J=9 Hz, 2H), 4.80 (s, 2H), 4.60 (quartet, J=7 Hz, 2H), 3.36 (septet, J=7 Hz, 1H), 1.51 (t, J=7 Hz, 3H), 1.44 (d, J=7 Hz, 6H). ESI-LCMS m/z 562 (M+H)+.
