Inside the glovebox, the tetrafluoroborate salt SIPr tBu •HBF4 (100 mg, 0.17 mmol, 1 equiv) was suspended in THF (0.05 M) and NaH (16.2 mg, 4 equiv) was added in. The mixture was taken outside the glovebox and sonicated at room temperature for 4 hours, then the mixture was brought back inside the glovebox. After removal of the solid by-products by filtration through a pad of Celite on a frit. The solution was concentrated then the solid is washed with pentane to afford desired carbene SIPr tBu (42.0 mg, 0.083 mmol, 49% yield).