2,2′-diamino-9,9′-spirobifluorene (3.46 g, 10 mmol), iodobenzene (6.8 mL, 60 mmol), Pd(OAc)2 (0.112 g, 0.5 mmol), sodium-tert-butoxide (14.4 g, 150 mmol) and tri-tert-butylphosphine (20 mL, 0.05 M in toluene, 1.0 mmol) were mixed in a flask containing with toluene (100 mL). The mixture was refluxed overnight. The solution was quenched with water and extracted twice with chloroform. The combined organic extracts were dried over MgSO4 and concentrated by rotary evaporation. Column chromatography on silica gel (hexane/chloroform=4/1) afforded products [2,2′-Bis(diphenylamino)-9,9′-spirobifluorene, hereinafter named as 22DPSF] as a white solid (4.5 g, 70%).
