Few drops of DMF were added as an internal standard for 1 H NMR analysis. A sample from this initial solution was dissolved in CDCl3 and was measured as the to sample in 1H NMR spectrometer. Subsequently, the flask was purged with argon gas for 25 minutes. The solution was left to react at 75 °C in an oil bath with magnetic stirring for 24 hours. The reaction was quenched by lowering the temperature and by exposing the reaction mixture to air. A sample from the reacted solution was dissolved in CDCl3 and was measured as the tfinal sample in 1 H NMR spectrometer.