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A mixture of 3-(2,4-dimethoxyphenylamino)phthalic acid (0.75 g, 2.4 mmol) and rac-α-aminoglutarimide hydrochloride (0.40 g, 2.4 mmol) in pyridine (10 mL) was heated to reflux for 16 hours. The mixture was cooled and evaporated under vacuum. The residue was dissolved in ethyl acetate (150 mL), washed with dilute aqueous HCl (2×100 mL) and water (2×100 mL), and evaporated. The residue was chromatographed using a hexanes-ethyl acetate gradient, eluting 0.64 g of the product at 25:75 hexanes-ethyl acetate, in 67% yield: mp 208-210° C.; 1H NMR (DMSO-d6) δ 2.04-2.09 (m, 1H), 2.54-2.64 (m, 2H), 2.83-2.92 (m, 1H), 3.78 (s, 3H), 3.79 (s, 3H), 5.12 (dd, J=12.7 Hz, J=5.4 Hz, 1H), 6.57 (dd, J=8.6 Hz, J=2.6 Hz, 1H), 6.71 (d, J=2.6 Hz, 1H), 7.00 (d, J=8.6 Hz, 1H), 7.15 (d, J=7.0 Hz, 1H), 7.29 (d, J=8.7 Hz, 1H), 7.54 (t, J=7.9 Hz, 1H), 7.95 (s, 1H), 11.15 (s, 1H); 13C NMR (DMSO-d6) δ 22.1, 31.0, 48.7, 55.4, 55.7, 99.5, 104.7, 110.4, 112.2, 118.3, 120.1, 125.2, 132.1, 136.1, 144.2, 153.7, 157.9, 167.2, 168.9, 170.1, 172.8; Anal. calcd for C21H19N3O6.0.3H2O: C, 60.81; H, 4.76; N, 10.13. Found: C, 60.87; H, 4.64; N, 10.00.
