N[C:2]1[CH:9]=[CH:8][CH:7]=[C:6]([O:10][CH:11]([F:13])[F:12])[C:3]=1[C:4]#[N:5].[ClH:14].N([O-])=O.[Na+].[S:19](=[O:21])=[O:20]>C(O)(=O)C.O>[C:4]([C:3]1[C:6]([O:10][CH:11]([F:13])[F:12])=[CH:7][CH:8]=[CH:9][C:2]=1[S:19]([Cl:14])(=[O:21])=[O:20])#[N:5]2-Amino-6-difluoromethoxy-benzonitrile (6.4 g, 35 mmol) is dissolved in glacial acetic acid (50 ml). Hydrochloric acid (37%, 12.7 g) is added dropwise at ambient temperature. This mixture is cooled to 5° C. and a solution of sodium nitrite (2.5 g, 36.4 mmol) in Water (8 ml) is added dropwise. The reaction mixture is stirred at 0° C. for 1 hour. The resulting diazonium salt solution is added dropwise at ambient temperature to a mixture of glacial acetic acid (100 ml) saturated at ambient temperature with sulfur dioxide and a solution of CuCl2 (2.18 g, 16.2 mmol) in water (5 ml). The resulting mixture is stirred at ambient temperature for 2 hours. The reaction mixture is poured into an ice/water and extracted three times with dichloromethane. The combined organic phases are dried over sodium sulfate and concentrated to give 2-Cyano-3-difluoromethoxy-benzenesulfonyl chloride (8.5 g, 91% yield) which is used without further purification. 1H-NMR (CDCl3, 400 MHz): 8.10 (d, 1H), 7.85 (t, 1H), 7.75 (d, 1H), 6.75 (t, 1H) ppm.
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