[Br:1][C:2]1[CH:17]=[N:16][C:5]2[NH:6][C:7]3[CH:12]=[N:11][C:10]([C:13]([NH2:15])=O)=[CH:9][C:8]=3[C:4]=2[CH:3]=1.C(N(CC)CC)C.FC(F)(F)C(OC(=O)C(F)(F)F)=O>C1COCC1>[Br:1][C:2]1[CH:17]=[N:16][C:5]2[NH:6][C:7]3[CH:12]=[N:11][C:10]([C:13]#[N:15])=[CH:9][C:8]=3[C:4]=2[CH:3]=1To a cooled solution (0° C.) of a mixture of 3-bromo-9H-dipyrido[2,3-b;4′,3′-d]pyrrole-6-carboxylic acid amide (5.0 g, 17.2 mmol) and triethylamine (24.0 mL, 172 mmol) in THF (200 mL) was slowly added trifluoroacetic anhydride (12.0 mL, 86 mmol). Upon complete addition, the reaction mixture was allowed to warm to ambient temperature and the stirring was continued for an additional 4 h. After this time, the solvent was removed in vacuo and the resultant residue was loaded onto H-MN. The residue was then purified by flash chromatography (silica, 330 g column, ISCO, 0-100% ethyl acetate in hexane) to afford the title compound as a pale brown solid (2.30 g, 49%). 1H NMR (DMSO-D6, 300 MHz): 13.05 (s, 1H), 9.08-9.04 (m, 2H), 8.91 (d, J=1.1 Hz, 1H), 8.79 (d, J=2.3 Hz, 1H). LCMS (Method B): RT=2.98 min, M+H+=271, 273.
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