[N+:1]([C:4]1[CH:11]=[CH:10][C:7]([CH2:8]Br)=[CH:6][CH:5]=1)([O-:3])=[O:2].[CH2:12]([O:14][C:15]([C:17]1[NH:18][C:19]2[C:24]([CH:25]=1)=[CH:23][CH:22]=[CH:21][CH:20]=2)=[O:16])[CH3:13].C(=O)([O-])[O-].[K+].[K+]>CC(C)=O>[N+:1]([C:4]1[CH:11]=[CH:10][C:7]([CH2:8][N:18]2[C:19]3[C:24](=[CH:23][CH:22]=[CH:21][CH:20]=3)[CH:25]=[C:17]2[C:15]([O:14][CH2:12][CH3:13])=[O:16])=[CH:6][CH:5]=1)([O-:3])=[O:2]A mixture of 4-nitrobenzyl bromide (1.85 g, 8.56 mmol), 1H-indole-2-carboxylic acid ethyl ester (1.62 g, 8.56 mmol) and potassium carbonate (4.17 g, 30 mmol) in 100 mL of acetone was refluxed for 1 day. After cooling to room temperature the reaction was quenched by addition of water and then partitioned between water and methylene chloride. The organic phase was dried over MgSO4, and concentrated to yield ethyl 1-(4-nitrobenzyl)-1H-indole-2-carboxylate as an off-white solid (2.0 g, 72%): 1H NMR (DMSO-d6) δ 1.27 (t, J=7.1 Hz, 3H), 4.26(q, J=7.1 Hz, 3H), 5.99(s, 2H), 7.18(t, J=7.0 Hz, 1H), 7.22 (d, J=9.0-Hz, 2H), 7.34 (t, J=7.0 Hz, 1H), 7.43 (s, 1H), 7.58 (d, J=13.8 Hz, 1H), 7.76 (d, J=13.8 Hz, 1H), 8.15 (d, J=9.0 Hz, 2H); MS (ESI) m/z 325 (MH+).
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