ClCCCl.[N:5]([C:8]1[C:17]([C:18]2[CH:23]=[CH:22][C:21]([N+:24]([O-:26])=[O:25])=[CH:20][CH:19]=2)=[N:16][C:15]([Br:27])=[CH:14][C:9]=1[C:10]([O:12][CH3:13])=[O:11])=[N+]=[N-]>C1COCC1.CCCCCCCC(O)=O.CCCCCCCC(O)=O.CCCCCCCC(O)=O.CCCCCCCC(O)=O.[Rh].[Rh]>[Br:27][C:15]1[CH:14]=[C:9]([C:10]([O:12][CH3:13])=[O:11])[C:8]2[NH:5][C:19]3[CH:20]=[C:21]([N+:24]([O-:26])=[O:25])[CH:22]=[CH:23][C:18]=3[C:17]=2[N:16]=11,2-Dichloroethane (30 mL) was added to a mixture of methyl 3-azido-6-bromo-2-(4-nitrophenyl)isonicotinate (6.5 g, 17 2 mmol), rhodium octanoate dimer (0.669 g, 0.859 mmol) and crushed 4A° molecular sieves (6.5 g). The reaction heated at 80° C. for 14 hr. The crude mixture was diluted with THF and filtered. The collected solid were then extracted with additional hot THF. The solvents were removed from the combined filtrates and the residue was suspended in methanol, filtered and air dried to leave methyl 2-bromo-7-nitro-5H-pyrido[3,2-b]indole-4-carboxylate (5.0 g, 13.4 mmol, 78% yield). MS (ESI) m/z 351.91 (M+H). 1H NMR (500 MHz, DMSO-d6) δ ppm 12.31 (1H, br. s.), 8.63 (1H, d, J=2.14 Hz), 8.45 (1H, d, J=8.55 Hz), 8.17 (1H, dd, J=8.55, 2.14 Hz), 8.08 (1H, s), 4.07 (3H, s).
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