Water (0.6 mL), sodium carbonate (0.16 g), 3-(tert-butoxycarbonylamino)phenylboronic acid (0.14 g), and tetrakis(triphenylphosphine)palladium(0) (29 mg) were added to an ethylene glycol dimethyl ether (2.0 mL) solution of tert-butyl 4-bromo-2-nitrobenzoate (0.15 g), followed by heating to reflux under a nitrogen atmosphere for 2 hours. The reaction mixture was cooled to room temperature, and then ethyl acetate and a saturated aqueous solution of sodium bicarbonate 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 [eluent: 95-91% hexane/ethyl acetate] to obtain 0.17 g of tert-butyl 4-(3-(tert-butoxycarbonylamino)phenyl)-2-nitrobenzoate as a light yellow solid.
