3-Amino-6-[1-(tert-butoxycarbonyl)-3-iodoindol-2-yl]phtalimide (150 mg, 0.298 mmol) was dissolved in diethylamine (7.5 mL), and the solution was added with bis(triphenylphosphine)dichloropalladium (16.7 mg, 0.0234 mmol), copper iodide (11.4 mg, 0.0596 mmol) and 3-butyn-1-ol (0.226 mL, 2.98 mmol), followed by stirring at 50° C. for 3.7 hours under argon atmosphere. The reaction mixture was added with water and extracted with ethyl acetate. The organic layer was washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure and the residue was purified by preparative thin-layer chromatography (chloroform/methanol=10/1) to obtain 3-amino-6-[1-(tert-butoxycarbonyl)-3-(4-hydroxy-1-butynyl)indol-2-yl]phtalimide (115 mg, yield 87%).
