[Cl:1][C:2]1[S:3][C:4]2[CH:10]=[C:9]([N+:11]([O-])=O)[CH:8]=[CH:7][C:5]=2[N:6]=1>C(O)(=O)C.[Fe]>[Cl:1][C:2]1[S:3][C:4]2[CH:10]=[C:9]([NH2:11])[CH:8]=[CH:7][C:5]=2[N:6]=1Suspend 2-Chloro-6-nitro-benzothiazole (21.43 g, 99.8 mmol) in glacial acetic acid (300 mL). Add elemental iron (12.9 g, 231 mmol) and stir at 40° C. for 5 h. Filter the reaction mixture through Celite®, concentrate in vacuo, and adsorb onto silica gel. Subject the residue to silica gel flash column chromatography in two portions [(120 g column, 0-10% CH3OH/CH2Cl2), (120 g column, 0-5% CH3O/CH2Cl2)] to yield the desired product (6.17 g, 33%). mass spectrum (m/e): 185.0 (M+1).
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