2-Phenyl-4-bromoaniline (564.7 mg, 2.28 mmol) was dissolved in N,N-dimethylformamide (25 mL) and, at room temperature, thereto were added tert-butyl-3-butenoate (582.5 mg, 4.10 mmol), tri-(o-tolyl)phosphine (1.87 g, 6.16 mmol), and diisopropylethylamine (0.78 mL, 4.56 mmol). The reaction mixture was deaerated, palladium acetate (67.4 mg, 0.30 mmol) was added, and the mixture was deaerated again. After stirring at 90° C. overnight, the reaction mixture was filtered through celite and washed with ethyl acetate (120 mL). The organic layer was washed with a saturated aqueous solution of sodium chloride (50 mL), thereafter dried over sodium sulfate, filtered, and concentrated under reduced pressure. The residue was purified by a silica gel column to obtain tert-butyl (3E)-4-(3-amino-4-phenylphenyl)-3-butenoate (555.8 mg).
