[CH3:1][O:2][C:3](=[O:17])[C:4]1[CH:9]=[CH:8][C:7]([CH2:10][CH:11]=[CH:12][N:13](C)C)=[CH:6][C:5]=1[Cl:16].[NH2:18]N>C(O)(=O)C>[CH3:1][O:2][C:3](=[O:17])[C:4]1[CH:9]=[CH:8][C:7]([C:10]2[CH:11]=[CH:12][NH:13][N:18]=2)=[CH:6][C:5]=1[Cl:16]A solution of 2-chloro-4-(3-dimethylamino-2-propen-1-yl)-benzoic acid methyl ester of Step B (6.13 g, 22.9 mmol) and anhydrous hydrazine (1.44 mL, 45.8 mmol) in 15 mL of glacial acetic acid was heated at 90° C. for 30 minutes. The reaction mixture was concentrated in vacuo and the residue partitioned between ethyl acetate and water. The organic layer was washed with water and brine and dried over sodium sulfate. The solvent was evaporated and the residual solid triturated with diethyl ether-hexane to give the title compound (5.1 g) as an orange solid.
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