[N+:1]([C:4]1[CH:20]=[CH:19][C:7]2[N:8]=[C:9]([NH:11][CH2:12][CH2:13][N:14]3[CH2:18][CH2:17][CH2:16][CH2:15]3)[S:10][C:6]=2[CH:5]=1)([O-])=O.Cl[Sn]Cl.N.CO.C(Cl)Cl>C(O)C>[NH2:1][C:4]1[CH:20]=[CH:19][C:7]2[N:8]=[C:9]([NH:11][CH2:12][CH2:13][N:14]3[CH2:18][CH2:17][CH2:16][CH2:15]3)[S:10][C:6]=2[CH:5]=1A suspension of 6-nitro-2-(2-pyrrolidin-1-ylethylamino)benzothiazole (Example 11, 50 mg, 0.17 mmol) and SnCl2 (161 mg, 0.85 mmol) in 20 mL of ethanol (denatured) was heated at reflux for 4 hours. After cooling the mixture was partitioned between 50 mL of ethyl acetate and 20 mL of 1.0N aqueous NaOH. The organic layer was dried over sodium sulfate and concentrated to give a yellow residue which was subjected to silica gel column chromatography (5% 2M NH3/MeOH:95% CH2Cl2). Yield: 65%, 1H-NMR (CD3OD): δ 8.70 (d, 1H, J=8.3 Hz); 8.47 (d, 1H, J=2.0 Hz); 8.21 (dd, 1H, J=6.3, 1.9 Hz); 5.05 (t, 2H, J=6.3 Hz); 4.28 (t, 2H, J=6.8 Hz); 4.14 (m, 4H); 3.33 (m, 4H).
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