P([CH2:5][C:6]([O:8][CH3:9])=[O:7])(O)(O)=O.[H-].[Na+].[H][H].[CH3:14][O:15][C:16]1[CH:21]=[CH:20][C:19]2[NH:22][CH:23]=[C:24]([CH:25]=O)[C:18]=2[CH:17]=1.P(=O)([O-])[O-]>O1CCCC1.ClCCl>[CH3:9][O:8][C:6](=[O:7])[CH:5]=[CH:25][C:24]1[C:18]2[C:19](=[CH:20][CH:21]=[C:16]([O:15][CH3:14])[CH:17]=2)[NH:22][CH:23]=1To a cold solution (ice bath) of methyl phosphonoacetate (13.74 g, 0.065 mol) in tetrahydrofuran (120 mL) under nitrogen, was added sodium hydride (2.6 g, 0.065 mol, 60%) in one portion, and stirred until hydrogen evolution ceased. A solution of commercially available 5-Methoxyindole-3-carboxyaldehyde 2 (5.2 g, 0.029 mol) in tetrahydrofuran (80 mL) was added, over a period of 60 minutes, to the phosphonate solution. The reaction mixture was heated to 55° C. for 24 h after which the mixture was diluted with dichloromethane (DCM, 500 mL) and washed with water (200 mL; 3×). The organic layer was washed once with brine, dried over anhydrous sodium sulfate, and evaporated under reduced pressure to give yellow-tinted oil and purified by filtering through a silica plug. The filtrate was evaporated to afford 3 as an off white solid (6.2 g; 78% yield; M+1=232.0).
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