Ethyl 2-iodophenylcarbamate (1 mmol), cuprous iodide (CuI, 19 mg, 0.1 mmol), and sodium sulfide nonahydrate (Na2S-9H2O, 3 mmol) were added to the Schlenk tube. The reaction tube was evacuated and replaced with argon (repeated 3 times), and then N,N-dimethylformamide (DMF, 2 mL) was added. The reaction mixture was stirred at 80 °C for 10-16 hours. Upon completion of the reaction, acetic acid (AcOH, 3 mL) was added to the cooled reaction mixture and the mixture was continued to be stirred at 130 °C for 36 hours. At the end of the reaction, saturated sodium bicarbonate solution (10 mL) was added for neutralization and then the reaction mixture was extracted with ethyl acetate. The organic layer was washed sequentially with water, saturated saline and dried with anhydrous sodium sulfate. After the solvent was removed by distillation under reduced pressure, the residue was purified by silica gel column chromatography to obtain the target product o-chlorobenzothiazolone.
