[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([N+:12]([O-])=O)=[C:6]([CH:11]=1)[NH:7][CH:8]([CH3:10])[CH3:9].[Cl-].[NH4+].C1C[O:20][CH2:19]C1>C(O)C.O.[Fe]>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]2[NH:12][C:19](=[O:20])[N:7]([CH:8]([CH3:10])[CH3:9])[C:6]=2[CH:11]=1A mixture of 5-chloro-N-isopropyl-2-nitroaniline (Step 1 of Example 12, 0.76 g, 3.54 mmol), iron (0.99 g, 17.7 mmol) and ammonium chloride (0.38 g, 7.08 mmol) was suspended in ethanol (27 mL) and H2O (9 mL). Then, the mixture was heated at 80° C. for 3 h. After cooling, the insoluble materials was filtered off on a pad of Celite, and the filtrate was evaporated under reduced pressure. To the residue was added N,N′-carbonyldiimidazole (CDI, 0.57 g, 3.50 mmol) and THF (10 mL) and then stirred at 100° C. for 10 h. After cooling, the volatile materials were removed under reduced pressure and the residue was partitioned between ethylacetate and H2O. After extraction with ethylacetate (3 times), the combined organic phase was washed with brine, dried over MgSO4 and concentrated. The residue was chromatographed on a column of silica gel eluting with hexane/ethyl acetate (2:1) to give 0.30 g (40%) of the title compound as a white solid.
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