N[C:2]1[C:12]([O:13][CH3:14])=[CH:11][C:5]([C:6]([O:8][CH2:9][CH3:10])=[O:7])=[CH:4][C:3]=1[Cl:15].C(#N)C.[I:19]CI.N(OCCC(C)C)=O>CCCCCCC.C(OCC)(=O)C>[Cl:15][C:3]1[CH:4]=[C:5]([CH:11]=[C:12]([O:13][CH3:14])[C:2]=1[I:19])[C:6]([O:8][CH2:9][CH3:10])=[O:7]
To ethyl 4-amino-3-chloro-5-methoxybenzoate (15.8 g, 68.8 mmol), were added acetonitrile (40 mL) and diiodomethane (22.2 mL, 275 mmol) in this order, and the mixture was stirred at 70° C., and then isoamyl nitrite (13.9 mL, 103 mmol) was added dropwise thereto over 10 minutes. The mixture was stirred at 70° C. for 40 minutes. The mixture was returned to room temperature, the solvent was then distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (a mixed solvent of n-heptane and ethyl acetate: n-heptane/ethyl acetate=8/1 then 5/1) to obtain the title compound (15.6 g, 45.8 mmol)
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