[CH3:1][C:2]([O:5][C:6]([NH:8][C:9]1[S:13][C:12]2[CH:14]=[C:15]([N+:18]([O-])=O)[CH:16]=[CH:17][C:11]=2[N:10]=1)=[O:7])([CH3:4])[CH3:3].[H][H]>CN(C)C=O.[Pd]>[CH3:4][C:2]([O:5][C:6]([NH:8][C:9]1[S:13][C:12]2[CH:14]=[C:15]([NH2:18])[CH:16]=[CH:17][C:11]=2[N:10]=1)=[O:7])([CH3:1])[CH3:3]6-Nitrobenzothiazol-2-yl tert-butyl carbamate (4.68 g, 15.8 mmol) was dissolved in dimethylformamide (120 mL) and palladium on charcoal (841 mg, 10% Pd, 0.79 mmol Pd) was added. The air was replaced with hydrogen (1 bar) and the mixture was vigorously stirred at 60° C. until completion of the reaction (2 h). The palladium was removed by filtration through a pad of celite and the solution was concentrated to 20 mL. Water (200 mL) was added. After stirring for 1 h, the precipitated 6-aminobenzothiazol-2-yl tert-butyl carbamate was filtered off and washed with water. Additional product was obtained by repeated filtration of the mother liquor. A total of 3.24 g (12.2 mmol, 77%) of a grey solid was obtained. LC/ESI-MS: m/z=266 [M+H]+; m/z=264 [M−H]−; Rt=2.54 min.
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