Reaction Steps
To a stirred suspension of 4-aminomethyl-2-(2,6-dioxo-piperidin-3-yl)-isoindole-1,3-dione hydrochloride (0.7 g, 2.16 mmol) in CH2Cl2 (60 ml), was added diisopropylethylamine (0.94 mL, 5.4 mmol) and 3,4-dimethyoxybenzoyl chloride (0.6 g, 2.8 mmol). The mixture was stirred at room temperature overnight followed by the addition of MeOH (1 mL). The reaction mixture was then washed with water (40 mL), 1N HCl (2×40 mL), and brine (40 mL), dried over MgSO4, and concentrated in vacuo. The resulting oil was purified by ISCO silica gel flash chromatography (eluent: 0% MeOH in CH2Cl2 to 5% MeOH in 10 min then stay at this ratio for 15 min) to afford N-[2-(2,6-dioxo-piperidin-3-yl)-1,3-dioxo-2,3-dihydro-1H-isoindol-4-yl-methyl]-3,4-dimethoxy-benzamide as a white solid (0.8 g, 79%): mp, 198-200° C.; HPLC: Waters Symmetry C-18, 3.9×150 mm, 5 micro, 1 mL/min, 240 nm, 40/60 (CH3CN/H2O): tR=2.2 min. (99%); 1H NMR (DMSO-d6): δ 2.06-2.10 (m, 1H), 2.51-2.59 (m, 2H), 2.64 (m, 1H), 3.81 (s, 6H), 4.94 (d, J=5.9 Hz, 2H), 5.14-5.20 (dd, J=5, 12 Hz, 1H), 7.06 (d, J=8.5 Hz, 1H), 7.51-7.58 (m, 2H), 7.83-7.70 (m, 3H), 9.02 (t, J=6 Hz, 1H), 11.15 (s, 1H). 13C NMR (DMSO-d6) δ: 21.97, 30.92, 38.22, 48.86, 55.53, 55.60, 110.67, 110.92, 120.56, 121.80, 126.10, 127.05, 131.50, 133.06, 134.77, 139.66, 148.28, 151.44, 166.09, 166.96, 167.57, 169.83, 172.74. Anal Calcd for C23H21N3O7+0.2H2O: C, 60.71; H, 4.74; N, 9.23. Found: C, 60.39; H, 4.51; N, 8.99.
