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-difluorobenzoyl chloride (0.5 g, 2.8 mmol). The mixture was stirred at room temperature overnight and a suspension was obtained. The reaction mixture was quenched with MeOH (1 mL) and was filtered. The solid was rinsed with CH2Cl2 (5 mL) and then dissolved in acetone (4 mL). Ether (10 mL) and hexane (10 mL) were added to the solution and the resulting suspension was filtered to afford N-[2-(2,6-dioxo-piperidin-3-yl)-1,3-dioxo-2,3-dihydro-1H-isoindol-4-ylmethyl]-3,4-difluoro-benzamide as a white solid (0.7 g, 75%): mp, 218-220° C.; HPLC: Waters Symmetry C-18, 3.9×150 mm, 5 micro, 1 mL/min, 240 nm, 40/60 (CH3CN/H2O): tR=4.1 min. (99%); 1H NMR (DMSO-d6): δ 2.06-2.11 (m, 1H), 2.51-2.64 (m, 2H), 2.87-2.93 (m, 1H), 4.95 (d, J=5.8 Hz, 2H), 5.15-5.21 (dd, J=5, 12 Hz, 1H), 7.55-8.01 (m, 6H), 9.26 (t, J=6 Hz, 1H), 11.15 (s, 1H). 13C NMR (DMSO-d6) δ: 21.96, 30.92, 39.20, 48.86, 116.77, 116.65, 116.89, 117.51, 117.74, 121.95, 124.75, 124.80, 124.85, 124.89, 127.18, 131.28, 131.32, 131.39, 131.53, 133.15, 134.82, 138.86, 147.42, 147.59, 149.70, 149.87, 150.68, 150.85, 153.02, 153.19, 164.45, 166.93, 167.49, 169.81, 172.74. Anal Calcd for C21H15F2N3O5: C, 59.02; H, 3.54; N, 9.83; F, 8.89. Found: C, 59.12; H, 3.60; N, 9.68; F, 8.86.
