Water (0.6 mL), sodium carbonate (70 mg), 2-nitrophenylboronic acid (44 mg), and tetrakis(triphenylphosphine)palladium(0) (13 mg) were added to an ethylene glycol dimethyl ether (2.0 mL) solution of tert-butyl 4-bromo-2-(5-phenylpyridine-3-carboxamido)benzoate (0.10 g), followed by heating to reflux under a nitrogen atmosphere for 2 hours and 30 minutes. The reaction mixture was cooled to room temperature, and then sodium carbonate (23 mg), 2-nitrophenylboronic acid (37 mg), and tetrakis(triphenylphosphine)palladium(0) (13 mg) were added thereto, followed by heating to reflux under a nitrogen atmosphere for 2 hours and 50 minutes. The reaction mixture was cooled to room temperature, and a 10% aqueous solution of citric acid and ethyl acetate were added thereto. The organic layer was separated, washed with a saturated aqueous solution of sodium chloride, and dried over anhydrous magnesium sulfate, and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography [Fuji Silysia Chemical Ltd., PSQ100B (spherical), eluent: 91-80% hexane/ethyl acetate] to obtain 68 mg of tert-butyl 4-(2-nitrophenyl)-2-(5-phenylpyridine-3-carboxamido)benzoate as a light green solid.
