To 8.00 g of anhydrous aluminum chloride suspended in 100 ml of dichloroethane was added dropwise 3.20 g of 2-methylpropanoyl chloride dissolved in 50 ml of dichloroethane under ice cooling. Then, to the mixture was added 5.27 g of 2-(1,3-isoindolinedion-2-yl)indane, and the mixture was stirred for 3 hours. The reaction mixture was poured into ice water containing hydrochloric acid, the organic layer was collected by separation, washed with water and dried, and then the solvent was removed. The resulting crystals were recrystallized from ethyl acetate-n-hexane to obtain 4.92 g of 2-(1,3-isoindolinedion-2-yl )-5-(2-methylpropionyl)indane.
