[CH2:1]([O:3][C:4](=[O:17])[C:5](=[CH:13]OCC)[C:6]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=O)[CH3:2].[N+:18]([CH2:21][C:22]([NH2:24])=[O:23])([O-:20])=[O:19].C([O-])(=O)C.[Na+].Cl>C(O)C>[N+:18]([C:21]1[C:22](=[O:23])[NH:24][C:6]([C:8]([O:10][CH2:11][CH3:12])=[O:9])=[C:5]([C:4]([O:3][CH2:1][CH3:2])=[O:17])[CH:13]=1)([O-:20])=[O:19]Diethyl(ethoxymethylene)oxalacetate (5.63 g, 0.023 mol,) is dissolved under N2 atmosphere in 20 mL of absolute ethanol and cooled to 0° C. Nitroacetamide (2.00 g, 0.019 mol,) (S. K. Brownstein, J. Org. Chem 23, 113 (1958)) and sodium acetate (1.56 g, 0.019 mol,) are added and the mixture is stirred at room temperature for 15 hours. The suspension is diluted with 15 mL of absolute ethanol and acidified to pH 2 with concentrated HCl. The inorganics are removed by filtration and the filtrate is concentrated to an oily solid which is gravity chromatographed, first with methylene chloride and then2% methanol in methylene chloride. The fractions are combined and stripped to give 4.28 g of the title product as a yellow solid, 78.4% yield, melting point 144°-145° C.
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