[CH2:1]([O:3][C:4]1[CH:5]=[C:6]2[C:10](=[CH:11][CH:12]=1)[N:9](CN(C)C)[CH:8]=[CH:7]2)[CH3:2].[N+:17]([CH:20]([CH3:25])[C:21]([O:23][CH3:24])=[O:22])([O-:19])=[O:18].[C:26]1(C)C=CC=CC=1.CC(C)=O>C1(C)C=CC=CC=1.C(Cl)(Cl)Cl>[CH3:24][O:23][C:21](=[O:22])[C:20]([CH3:26])([N+:17]([O-:19])=[O:18])[CH2:25][C:7]1[C:6]2[C:10](=[CH:11][CH:12]=[C:4]([O:3][CH2:1][CH3:2])[CH:5]=2)[NH:9][CH:8]=1A mixture of (5-ethoxy-1H-indol-ylmethyl)-dimethyl-amine (2.18 g, 10 mmol) and commercially available methyl 2-nitro-propionate (1.60 g, 12 mmol, 1.2 equiv) in dry toluene (17 ml) is refluxed. When TLC (toluene-acetone, 9:1) indicates the absence of starting material the mixture is cooled and is diluted with chloroform (35 ml). It is subsequently washed with 10% aqueous HCl (2×10 ml), water (10 ml), 5% aqueous NaOH (2×10 ml), water (10 ml), and 20% aqueous Na2SO4 (10 ml), is dried, and the solvents are removed under reduced pressure. The residue is purified by column chromatography (light petroleum-ethyl acetate, 4:1→7:3) to give (+/−)-3-(5-ethoxy-1H-indol-3-yl)-2-methyl-2-nitro-propionic acid methyl ester (2.07 g, 68%) as a white solid. M.p. 80-82° C. (from ethyl acetate-hexane).
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