A 2 L, 3-necked round bottomed flask equipped with a heating mantle, condenser, overhead stirrer, thermocouple, and N2(g) inlet was charged with 2-[2-Nitro-4-(3-nitro-benzoyl)-phenyl]-malonic acid diethyl ester (105 g, 0.24 mol), DMSO (1 L) and H2O (87 mL) The reaction was heated at 110° C. for 11 h. Thin layer chromatographic analysis (Hexanes/ethylacetate 6:4) indicated completion of reaction. The reaction mixture was cooled to room temperature and was diluted with ethyl acetate (4 L). The organic layer was washed with brine (3×4 L), dried over Na2SO4 and concentrated. Methyl t-butyl ether (1 L) was added to the solids and stirred. The product was filtered and washed with Methyl t-butyl ether (2×250 mL). The solids collected were dried in the vacuum oven at 45° C. for 24 hours to yield 89% of pure [2-Nitro-4-(3-nitro-benzoyl)-phenyl]-acetic acid ethyl ester (77 g, 0.21 mol).
