Reaktionsschritte
A mixture of 3-(2,4-dimethoxyphenylamino)phthalic acid (0.37 g, 1.2 mmol) and (3S)-3-amino-3-methyl-piperidine-2,6-dione hydrobromide (0.28 g, 1.2 mmol) in pyridine (10 mL) was heated to reflux for 24 hours. The mixture was cooled and evaporated under vacuum. The residue was dissolved in ethyl acetate (100 mL), washed with dilute aqueous HCl (2×100 mL) and water (2×100 mL), and evaporated. The residue was purified by ISCO silica gel flash chromatography using a hexanes-ethyl acetate gradient, eluting 0.20 g of the product, an orange solid, at 50:50 hexanes-ethyl acetate, in 41% yield: mp 255-257° C.; HPLC, Waters Symmetry C-18, 3.9×150 mm, 5 μm, 1 mL/min, 240 nm, 65/35 (CH3CN/0.1% H3PO4): tR=2.72 (97.30%); 1H NMR (DMSO-d6) δ 1.91 (s, 3H), 2.05-2.08 (m, 1H), 2.59-2.73 (m, 3H), 3.79 (s, 6H), 6.57 (d, J=7.5 Hz, 1H), 6.71 (s, 1H), 6.97-7.08 (m, 2H), 7.27 (d, J=8.1 Hz, 1H), 7.52 (m, 1H), 7.94 (s, 1H), 11.01 (s, 1H); 13C NMR (DMSO-d6) δ 21.0, 28.6, 29.2, 55.4, 55.7, 58.5, 99.5, 104.7, 110.2, 111.8, 118.1, 120.1, 125.0, 131.9, 136.0, 144.0, 153.6, 157.9, 167.8, 169.8, 172.1, 172.4; Anal. calcd for C22H21N3O6.0.2H2O: C, 61.88; H, 5.05; N, 9.84. Found: C, 61.91; H, 5.01; N, 8.52.
