1-(2,4-diisopropyldibenzo[b,d]furan-3-yl)-2-phenyl-4,5-dihydro-1H-imidazole (7.4 g, 18.66 mmol) was dissolved in 200 mL of acetonitrile and 100 mL of dichloromethane. Potassium Permanganate (5.90 g, 37.3 mmol) and Clay K10 (12 g, 30.7 mmol) were ground in a mortar. The solid was then added carefully to the solution. Heat was generated after a few minutes. The reaction was monitored by TLC. The reaction was quenched with methanol after 1.5 h. The reaction mixture was filtered through Celite. The solvent was evaporated and the residue was purified by column. 5.3 g (72% yield) of pure product was obtained.
