General procedure for the synthesis of 2,3-dichlorobenzonitrile from 2,3-dichlorobenzaldehyde oxime: n-C4F9SO2F (20.0 mmol, 2.0 eq.) was slowly added dropwise using a syringe to a solution of dichloromethane (CH2Cl2, 20 mL) containing the substrate 2,3-dichlorobenzaldehyde oxime (10.0 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU. 50.0 mmol, 5.0 equiv) in a solution of dichloromethane (CH2Cl2, 20 mL). The reaction mixture was stirred at the same temperature for 10 min. Subsequently, the volatile components were removed by distillation under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography with the eluent being a solvent mixture of petroleum ether and ethyl acetate, resulting in the target product 2,3-dichlorobenzonitrile in 95% yield.
