Reaction Steps
To a mixture of (E)-tert-butyl 5-methoxy-3-(1-(pyridin-3-yl)but-1-en-3-yn-2-yl)-1H-indole-1-carboxylate (270 mg, 0.72 mmol, 1.0 eq.) in ethanol (40 mL) were added K2CO3 (1.2 g, 8.6 mmol, 12.0 eq.) and sodium methanolate (232 mg, 4.3 mmol, 6.0 eq.), and then, the reaction was stirred at room temperature for 3 days. The solvent was removed and the residue taken up in ethyl acetate. The organic layer washed with water, dried over MgSO4, filtered through a silica gel pad and then, evaporated under reduced pressure to afford, after trituration with diethyl ether, the compound (58) as a yellowish powder (180 mg, 91%). mp: 136° C.; IR νmax (cm−1): 2089 (νCC alcyne); 1H RMN (DMSO, 300 MHz) δ (ppm): 3.81 (3H, s, 5-methoxy), 4.64 (1H, s, H4′), 6.84 (1H, dd, J6-7=8.9 Hz, J6-4=2.3 Hz, H6), 7.29 (1H, s, H1′), 7.35 (1H, d, J7-6=8.9 Hz, H7), 7.42 (1H, dd, J5″-4″=7.3 Hz, J5″-6″=4.5 Hz, H5″), 7.49 (1H, d, J4-6=2.3 Hz, H4), 7.67 (1H, s, H2), 8.46 (2H, m, H4″ and H6″), 9.03 (1H, s, H2″), 11.37 (1H, s, indolic H); 13C NMR (DMSO, 75.5 MHz) δ (ppm): 55.4 (5-methoxy), 82.5 (C3′), 86.7 (C4′), 102.2 (C4), 111.7 (C6), 112.8 (C7), 114.2 (C2′), 117.7 (C3), 123.2 (C5″), 124.4 (C3a), 126.4 (C1′), 127.0 (C2), 132.2 (C7a), 132.7 (C3″), 134.3 (C4″), 147.9 (C6″), 149.8 (C2″), 154.0 (C5); ESI-MS: m/z 275.1 ([M+H]+); HRESI-MS: m/z 275.1176 (calcd for C18H15N2O+, 275.1184).
