[S:1]1[CH2:5][CH2:4][N:3]=[C:2]1[C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][CH:11]=[CH:10][C:9]=2[N+:15]([O-])=O.[Cl-].[Ca+2].[Cl-].C(O)C.Cl>[Fe].O>[S:1]1[CH2:5][CH2:4][N:3]=[C:2]1[C:6]1[NH:7][C:8]2[C:13]([CH:14]=1)=[CH:12][CH:11]=[CH:10][C:9]=2[NH2:15]
To a mixture of 2-(4,5-dihydro-1,3-thiazol-2-yl)-7-nitro-1H-indole (4.0 g), iron powder (4.0 g), calcium chloride (770 mg), ethanol (45 mL) and water (5 mL) was added 1N hydrochloric acid (0.2 mL), and the mixture was stirred at 80° C. for 2 hr. After cooling the reaction mixture to room temperature, and the insoluble material was filtered off. Saturated aqueous sodium hydrogen carbonate was added to the filtrate, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, dried (MgSO4) and concentrated. The residue was subjected to silica gel column chromatography (ethyl acetate) to give the title compound (1.9 g, yield 56%) as pale-yellow crystals.
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