34569-15-8

4-Chloro-1,2-benzenediamine (71.0 mg, 0.5 mmol) and 3,5-heptanedione (64.0 mg, 0.5 mmol) were used as raw materials, and the above materials and p-toluenesulfonic acid (9.5 mg, 0.05 mmol) were added sequentially in a 25 mL Schlenk flask. Subsequently, toluene (4.0 mL) was added and the reaction mixture was placed in a 60°C oil bath and stirred for 24 hours. After completion of the reaction, the solvent was evaporated under reduced pressure. The crude product was separated by silica gel column chromatography using petroleum ether/ethyl acetate as eluent to afford 5-chloro-2-ethyl-1H-benzo[d]imidazole in 95% yield.

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