Reaction Steps
The method of Andreani, A.; Granaiola, M.; Leoni, A.; Locatelli, A.; Morigi, R.; Rambaldi, M.; Roda, A.; Guardigli, M.; Traniello, S.; Spisani, S. N-Benzyl-2-chloroindole-3-carboxylic acids as potential anti-inflammatory agents. Synthesis and screening for effects on human neutrophil functions and on COX1/COX2 activity. Eur J Med. Chem. 2004, 39, 785-91, was followed. Compound 9 (0.573 mmol, 1 equiv) was dissolved in 10 mL of acetone and treated with a solution of potassium permanaganate (KMnO4, 1.5 mmol) in water (5 mL). The reaction mixture was stirred at room temperature for 5 h, treated with 10% H2O2 until the pink color of KMnO4 was not observed and then filtered. The solvent was removed under reduced pressure and the resulting residue was filtered again (if necessary), acidified with 2M HCl and extracted with Et2O. The organic solvent was removed in vacuo and the residue was purified by column chromatography with hexane/EtOAc as eluting solvents. Yield: 62%; 1H NMR (300 MHz, CDCl3): δ 8.84 (s, 1 H), 7.92 (s, 1 H), 7.54-7.48 (m, 2 H), 7.41-7.29 (m, 3 H), 7.14 (d, J=6.6 Hz, 1 H), 4.12 (t, J=6.6 Hz, 2 H), 2.44 (s, 3 H), 1.87 (t, J=6.6 Hz, 3 H), 1.37-1.25 (m, 10 H), 0.86 (t, J=6.6 Hz, 3 H); 13C NMR (75 MHz, CDCl3): δ 170.3, 142.3, 141.9, 138.4, 138.2, 136.1, 136.0, 135.8, 128.5, 128.3, 127.4, 124.6, 120.3, 110.3, 106.3, 47.2, 31.7, 31.1, 29.8, 29.1, 22.6, 21.5, 21.5, 14.0.
