Water → 2,5-Dihydroxy-3-[2-(1-methyl-cyclopropyl)-1H-indol-3-yl]-[1,4]benzoquinone

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Reaction Steps

To a refluxing solution of 2,5-dichloro-3-[2-(1-methyl-cyclopropyl)-1H-indole-3-yl]-[1,4]benzoquinone (0.056 g, 0.16 mmol) in MeOH (6 mL) was added 10% aqueous NaOH (3 mL) dropwise. After refluxing for a half hour, the mixture was poured into cold water (20 mL). H2SO4 (10%) was added to acidify the mixture, which was extracted with EtOAc (3×10 mL). The organic layer was washed with brine (10 mL) and dried over Na2SO4. The solution was concentrated and purified by flash column chromatography (oxalic acid-coated silica gel) using 30% EtOAc in hexane as the eluent to afford 2,5-dihydroxy-3-[2-(1-methyl-cyclopropyl)-1H-indol-3-yl]-[1,4]benzoquinone (0.044 g, 87%) as dark blue needles from acetone/hexane. Melting Point 103° C. (dec). 1H NMR (d6-acetone): 0.55–0.62 (2H, m), 0.81–0.87 (2H, m), 1.45 (3H, s), 6.08 (1H, s), 6.93 (1H, dt, J=0.9, 8.1 Hz), 7.04 (1H, dt, J=1.2, 8.1 Hz), 7.22 (1H, d, J=7.8 Hz), 7.31 (1H, dd, J=0.9, 8.1 Hz), 9.0–10.1 (2H, br s), 10.34 (1H, br s). 13C NMR (d6-acetone): 13.3, 14.8, 24.4, 101.4, 103.6, 110.8, 112.3, 119.0, 119.5, 121.1, 128.4, 135.8, 142.2. IR (KBr): 3300, 3077, 2958, 2924, 1640, 1360, 1190, 746 cm−1. HRMS (EI): calculated for C18H15NO4 309.1001; found 309.0999.

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