[C:1]([Si:5]([CH3:23])([CH3:22])[O:6][CH2:7][CH2:8][C:9]1[C:17]2[C:16]([C:18](O)=[O:19])=[CH:15][CH:14]=[C:13]([CH3:21])[C:12]=2[NH:11][CH:10]=1)([CH3:4])([CH3:3])[CH3:2].C[CH2:25][N:26]=C=NCCCN(C)C.C1C=CC2N(O)N=NC=2C=1.C(N(C(C)C)CC)(C)C.CN>CN(C=O)C.O>[CH3:25][NH:26][C:18]([C:16]1[C:17]2[C:9]([CH2:8][CH2:7][O:6][Si:5]([C:1]([CH3:4])([CH3:3])[CH3:2])([CH3:23])[CH3:22])=[CH:10][NH:11][C:12]=2[C:13]([CH3:21])=[CH:14][CH:15]=1)=[O:19]To a solution of 3-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-7-methyl-1H-indole-4-carboxylic acid (150 mg, 0.45 mmol), EDCI (104 mg, 0.54 mmol) and HOBt (91.2 mg, 0.68 mmol) in DMF (3 mL) was added diisopropylethylamine (0.39 mL, 2.25 mmol) at room temperature. A solution of methylamine (0.45 mL of 2.0 M in THF, 0.90 mmol) was added to the mixture and the mixture was stirred overnight at room temperature. The solution was diluted with H2O (5 mL) and extracted with EtOAc (3×10 mL). The organic solution was washed brine (20 mL), dried (Na2SO4) and concentrated. The residue was purified by flash chromatography (silica, 40% EtOAc in hexanes) to give 140 mg (90%) of title compound as a pale yellow solid. 1H NMR (CDCl3): 300 MHz δ 8.28 (bs, 1H), 7.20 (m, 2H), 7.00 (d, J=7.35 Hz, 1H), 6.40 (bs, 1H), 3.91 (t, J=6.41 Hz, 2H), 3.08 (m, 5H), 2.54 (s, 3H), 0.88 (s, 9H), −0.08 (s, 6H).
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