Sulfuric Acid → 2,5-dichloro-3-(5-methoxy-1H-indole-3-yl)-[1,4]benzoquinone

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Reaktionsschritte

To a solution of 2,5-dichloro-1,4-benzoquinone (0.242 g, 1.37 mmol) in THF (3 mL) was added H2SO4 (35 μL, 0.68 mmol) at room temperature. To this mixture was added 5-methoxyindole (0.100 g, 0.68 mmol). After the reaction mixture was stirred for 1 hour at room temperature under nitrogen protection, DDQ (0.232 g, 1.02 mmol) was added. After stirring for 2 hours, the mixture was diluted with ethyl acetate (100 mL). The organic layer was washed with sat. NaHCO3 (3×20 mL) and brine (20 mL), and dried over Na2SO4. The solution was concentrated and purified by flash column chromatography using 15% EtOAc in hexane as eluent to afford 2,5-dichloro-3-(5-methoxy-1H-indole-3-yl)-[1,4]benzoquinone (0.211 g, 96%) as blue needles from benzene/hexane. Melting Point 195–196° C. 1H NMR (CDCl3): 6.78 (1H, d, J=2.4 Hz), 6.93 (1H, dd, J=2.1, 8.4 Hz), 7.23 (1H, s), 7.34 (1H, d, J=9.0 Hz), 7.54 (1H, d, J=3.0 Hz), 8.62 (1H, br s). 13C NMR (d6-acetone): 55.2, 103.8, 106.7, 112.4, 112.8, 126.5, 130.9, 131.0, 131.4, 133.4, 139.8, 143.7, 154.8, 177.8, 178.0. IR (KBr): 3328, 3043, 2924, 2855, 1675, 1638, 1543, 1484, 1260, 1227 cm−1. Anal. Calcd. for C15H9Cl2NO3: C, 55.93; H, 2.82; N, 4.35. Found: C, 55.72; H, 2.99; N, 4.24.

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