872305-97-0

60434-13-1

GENERAL METHODS: A mixture of N-methyl-2-oxo-N-phenylacetamide (0.4 mmol) and ferric chloride (10 mol%) was dissolved in 2 mL of dimethylsulfoxide (DMSO), and the reaction was stirred for 1.5 h at 100 °C under air atmosphere. The reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was cooled to room temperature, diluted with water and extracted with ethyl acetate. The organic layers were combined, washed with saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was removed by concentration under reduced pressure to give the crude product. Purification of the crude product by rapid column chromatography on silica gel (petroleum ether/ethyl acetate = 10:1) afforded 1-methyldihydroindole-2,3-dione as a red solid (60 mg, 93% yield).