C[O:2][C:3](=O)[CH2:4][CH2:5][N:6]1[C:18]2[CH:17]=[CH:16][CH:15]=[CH:14][C:13]=2[C:12]2[C:7]1=[CH:8][CH:9]=[CH:10][CH:11]=2.Cl.[NH2:21][OH:22].C[O-].[Na+].CO.C([O-])(O)=O.[Na+]>CN(C=O)C.C(OCC)(=O)C.O>[CH:17]1[C:18]2[N:6]([CH2:5][CH2:4][C:3]([NH:21][OH:22])=[O:2])[C:7]3[C:12](=[CH:11][CH:10]=[CH:9][CH:8]=3)[C:13]=2[CH:14]=[CH:15][CH:16]=1
3-Carbazol-9-yl-propionic acid methyl ester (22) (0.50 g, 1.97 mmol) and hydroxylamine hydrochloride (0.82 g, 12 mmol) were placed under argon and dissolved in DMF (8 mL). To it was added a 25% sodium methoxide solution in methanol (3.4 g, 16 mmol) which resulted in immediate precipitation of a white solid. The reaction was stirred for 24 h at room temperature after which was taken up in ethyl acetate (20 mL), water (10 mL) and of saturated aqueous NaHCO3 (10 mL). The organic layer was isolated and the aqueous layer was further extracted with ethyl acetate (2×20 mL). The combined organic layers were washed with brine (10 mL), dried (Na2SO4) and concentrated in vacuo. The crude extract was purified by HPLC to yield the title compound (234 mg, 47%) as a white solid. 1H NMR (400 MHz, DMSO): δ 10.46 (s, 1H), 8.75 (s, 1H), 8.14 (d, 2H, J=7.7 Hz), 7.60 (d, 2H, J=8.0 Hz), 7.45 (t, 2H, J=7.2 Hz), 7.20 (t, 2H, J=7.6 Hz), 4.61 (t, 2H, J=6.8 Hz), 2.48 (m, 2H). 13C NMR (100 MHz, CDCl3): δ 169.2, 140.2, 126.2, 122.6, 120.6, 119.3, 109.8, 39.3, 32.3. ESI-MS (m/z): [M+H]+ 254.1. Analytical HPLC: Purity=97%, tR=5.62 min, Method A.
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