Reaction Steps
To a solution of sodium methanolate (162 mg, 3.0 mmol, 2.0 eq.) in anhydrous ethanol (20 mL) were added, under an argon atmosphere, (5-methoxy-2-methyl-1H-indol-3-yl)-acetonitrile (300 mg, 1.5 mmol, 1.0 eq.) and, after 30 minutes stirring, pyridine-3-carbaldehyde (352 μL, 3.8 mmol, 2.5 eq.). The reaction apparatus was protected from light and the mixture heated at 50° C. for 12 hours. The reaction was allowed to cool to room temperature and then, the solvent was removed under reduced pressure and the crude taken up in ethyl acetate. The organic layer was washed with water and brine, dried over MgSO4 and then, evaporated. The residue was purified by silica gel flash-column chromatography (eluent: heptane/EtOAc, 40/60) to afford, after trituration with diethyl ether and dichloromethane, the compound (35) as a yellow solid (250 mg, 58%). IR □max (cm−1): 2212 (νCN); 1H NMR (DMSO, 300 MHz) δ (ppm): 2.54 (3H, s, 2′-methyl), 3.77 (3H, s, 5′-methoxy), 6.78 (1H, dd, J6′-7′=8.9 Hz, J6′-4′=2.4 Hz, H6′), 7.18 (1H, d, J4′-6′=2.4 Hz, H4′), 7.27 (1H, d, J7′-6′=8.9 Hz, H7′), 7.50 (1H, s, H3), 7.55 (1H, dd, J5″-4″=8.1 Hz, J5″-6″=4.8 Hz, H5″), 7.74 (1H, s, H3), 8.35 (1H, d, J4″-5″=8.1 Hz, H4″), 8.61 (1H, d, J6″-5″=4.8 Hz, H6″), 8.97 (1H, s, H2″), 11.45 (1H, s, indolic H); 13C NMR (DMSO, 75.5 MHz) δ (ppm): 12.6 (2′-methyl), 55.3 (5′-methoxy), 100.4 (C4′), 106.1 (C2), 106.9 (C3′), 110.9 (C6′), 111.9 (C7′), 118.0 (C1), 123.7 (C5″), 126.2 (C3a′), 129.9 (C2′), 130.5 (C3″), 134.6 (C3), 136.3 (C7a′), 137.6 (C4″), 149.8 (C6″), 150.0 (C2″), 154.1 (C5′); ESI-MS: m/z 290.1 ([M+H]+), 312.1 ([M+Na]+); HRESI-MS: m/z 290.1299 (calcd for C18H16N3O+, 290.1293).
