To a solution of 6-bromo-1′-pentylspiro[1-benzofuran-3,3′-indol]-2′(1′H)one (0.10 g, 0.26 mmol) in anhydrous toluene (5.00 mL) was added benzophenone imine (0.09 g, 0.52 mmol), sodium t-butoxide (0.03 g, 0.36 mmol), tris(dibenzylideneacetone) dipalladium(0) (0.01 g, 0.07 mmol) and (±)-2,2′-bis(diphenylphosphino)-1,1′-binaphthalene (0.12 g, 0.19 mmol). The reaction mixture was refluxed for 16 h, cooled down to ambient temperature, diluted with dichloromethane (50.0 mL) and filtered through a celite bed. The filtrate was concentrated in vacuo to dryness to give the title compound which was used in next step without purification.
