In a 3-neck round bottom flask, coupled with a reflux apparatus, potassium t-butoxide (92 mmol, 2.2 eq, 10.61 g), compound 3 (84 mmol, 2 eq, 33.66 g) and 120 ml of t-amyl alcohol were added under inert atmosphere along with a magnetic stirrer. The mixture was stirred and warmed up to 120 °C for 30 mins.