Since the reaction is exothermic and the temperature of the reaction mixture increases, an icewater bath was used to keep the reaction temperature below the boiling point of the THF. Then the reaction was stirred at room temperature for another 3 h before cooling down to 0 °C and quenching using water. The reaction mixture was diluted with ethyl acetate (EA), washed with water and brine successively, and then dried using Na2SO4. The solvent was removed under vacuum and the crude product was purified by silica gel chromatography using hexanes/EA (95/5) as eluent to give the oily monomer.