General procedure for the synthesis of 5-methoxyisoindolane-1,3-dione from 5-methoxy-1-indanone: In a stainless steel autoclave with PTFE lining, 0.01 g of MnO2 catalyst, 0.5 mmol of 5-methoxy-1-indanone, 0.2 g of ammonia (25 wt%) and 2 g of chlorobenzene were added in sequence. The reaction temperature was raised to 110 °C by an automatic temperature controller, followed by the passage of 0.6 MPa oxygen, which was maintained at a constant pressure, and the reaction was continued for 4 hours. Upon completion of the reaction, the reaction mixture was analyzed by GC-MS and the yield of 5-methoxyisoindolidine-1,3-dione was measured to be 85%.
