Reaction Steps
3,4-Dichlorophenyl isocyanate (0.5 g, 2.7 mmol) was added to a stirred suspension of 3-(4-aminomethyl-1-oxo-1,3-dihydro-isoindol-2-yl)-piperidine-2,6-dione hydrochloride (0.7 g, 2.1 mmol) and triethylamine (0.3 g, 2.9 mmol) in THF (30 mL). The mixture was stirred at room temperature overnight. The mixture was concentrated, and the residue was stirred with 1N HCl (30 mL). The mixture was filtered, and the solid was slurried with hot methanol (20 mL) to give 1-(3,4-dichloro-phenyl)-3-[2-(2,6-dioxo-piperidin-3-yl)-1-oxo-2,3-dihydro-1H-isoindol-4-ylmethyl]-urea (0.6 g, 67%) as a white solid: mp 253-255° C.; 1H NMR (DMSO-d6) δ 2.00-2.05 (m, 1H), 2.37-2.65 (m, 2H), 2.86-3.00 (m, 1H), 4.36-4.58 (m, 4H, 2CH2), 5.11-5.18 (dd, J=4.9 and 13.1 Hz, 1H, CH), 6.89 (t, J=5.6 Hz, 1H, NH), 7.24-7.84 (m, 6H, Ar), 8.96 (s, 1H, NH), 11.01 (s, 1H, NH); 13C NMR (DMSO-d6) δ 22.56, 31.17, 39.69, 46.19, 51.58, 117.86, 118.83, 121.58, 122.37, 128.29, 130.38, 130.86, 131.64, 135.27, 139.91, 140.56, 154.87, 168.05, 170.98, 172.81; Anal. calcd. for C21H18N4O4Cl2: C, 54.68; H, 3.93; N, 12.15; Cl, 15.37. Found: C, 54.52; H, 3.78; N, 11.89; Cl, 15.28.
