In a 50 mL two-necked flask under nitrogen protection, 4,4'-dimethoxydiphenylamine (2.00 g, 8.72 mmol), 2,2',7,7'-tetrabromo-9,9'-spirobifluorene (1.23 g, 1.94 mmol), sodium tert-butoxide (1.12 g, 11.6 mmol), tris(dibenzylideneacetone)dipalladium(0) (0.071 g, 0.078 mmol) and tri-tert-butylphosphine (0.025 g, 0.12 mmol). Subsequently, 15 mL of anhydrous toluene was added and the reaction mixture was stirred at 110 °C for 12 hours. After completion of the reaction, the mixture was cooled to room temperature, extracted with ethyl acetate, and the organic phase was washed with brine and dried with anhydrous magnesium sulfate. The product was purified by column chromatography (eluent: ethyl acetate/hexane=1/2), and removal of the solvent afforded 2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene as a beige solid in 45% yield (1.07 g).
