[NH2:1][C:2]1[C:11]2[N:10]=[CH:9][CH:8]=[CH:7][C:6]=2[C:5]2[CH:12]=[CH:13][C:14]([CH2:16][OH:17])=[CH:15][C:4]=2[N:3]=1>C(Cl)Cl.O=[Mn]=O>[NH2:1][C:2]1[C:11]2[N:10]=[CH:9][CH:8]=[CH:7][C:6]=2[C:5]2[CH:12]=[CH:13][C:14]([CH:16]=[O:17])=[CH:15][C:4]=2[N:3]=1A solution of (5-aminobenzo[f][1,7]naphthyridin-8-yl)methanol (from Example 85) (1.0 eq.) and activated MnO2 (20 eq.) in DCM (0.1 M) was stirred at ambient temperature over night. The reaction mixture was diluted with DCM. The MnO2 was filtered off, and the filtrate was concentrated en vaccuo to obtain a crude residue. The crude material was purified by flash chromatography on a COMBIFLASH® system (ISCO) using 0-10% MeOH/DCM to give 5-aminobenzo[f][1,7]naphthyridine-8-carbaldehyde as a yellow solid: 1H NMR (acetone-d6): δ 10.19 (s, 1H), 9.14 (dd, 1H), 9.01 (dd, 1H), 8.63 (d, 1H), 8.14 (d, 1H), 7.93 (dd, 1H), 7.81 (dd, 1H), 6.96 (br s, 2H). LRMS [M+H]=224.1
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