[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[NH:8][CH:7]=[C:6]2[CH:12]=[O:13].[H-].[Na+].CI.[C:18](=O)(O)[O-].[Na+]>CN(C=O)C>[CH3:1][O:2][C:3]1[CH:4]=[C:5]2[C:9](=[CH:10][CH:11]=1)[N:8]([CH3:18])[CH:7]=[C:6]2[CH:12]=[O:13]
5-Methoxyindole-3-carboxaldehyde (300 mg, 1.71 mmol) was added in portions over 5 min to a suspension of sodium hydride (82 mg, 2.05 mmol, 60% dispersion in mineral oil) in DMF (8 mL) stirring under argon. The mixture was stirred for 30 min, methyl iodide (0.13 mL, 2.05 mmol) was added and the mixture was stirred for 1 h. Sodium bicarbonate (10%, 40 mL) was added and the mixture was extracted with EtOAc (4×). The combined organic layers were washed with sodium bicarbonate (10%, 2×) and saturated NaCl, dried (MgSO4), filtered and evaporated. Column chromatography of the crude product (50:50 EtOAc:hexanes) afforded 43 (320 mg, 99%) as a light yellow solid; Rf=0.35 (50:50 EtOAc:hexanes); mp=130-132° C.; lit mp=132-133° C.53; 1H NMR (CDCl3): δ 9.95 (s, 1H), 7.79 (d, 1H, J=2.4 Hz), 7.62 (s, 1H), 7.25 (d, J=8.8 Hz), 6.96 (dd, 1H, J=2.4 and 8.9 Hz), 3.90 (s, 3H), 3.85 (s, 3H).
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