To a stirred mixture of 3-(5-aminomethyl-1-oxo-1,3-dihydro-isoindol-2-yl)-piperidine-2,6-dione hydrochloride (0.50 g, 1.40 mmol) and 2-chlorophenylisocyanate (0.16 mL, 1.40 mmol) in N,N-dimethylformamide (10 mL), was added triethylamine (0.38 mL, 2.7 mmol) at room temperature under nitrogen. After 2 h, 1 N aq. HCl (40 mL) was added and the solids were isolated by filtration and washed with water (20 mL). The crude product was triturated in EtOAc (50 mL) for 0.5 h. The product was isolated by filtration and dried in vacuo to give 1-(2-chloro-phenyl)-3-[2-(2,6-dioxo-piperidin-3-yl)-1-oxo-2,3-dihydro-1H-isoindol-5-ylmethyl]-urea as a white solid (0.56 g, 97% yield): HPLC: Waters Symmetry C18, 5 μm, 3.9×150 mm, 1 mL/min, 240 nm, 30/70 CH3CN/0.1% H3PO4, 6.35 min (98.37%); mp: 235-237° C.; 1H NMR (DMSO-d6) δ 1.77-2.14 (m, 1H, CHH), 2.23-2.47 (m, 1H, CHH), 2.60 (d, J=17.2 Hz, 1H, CHH), 2.77-3.04 (m, 1H, CHH), 4.32 (d, J=17.4 Hz, 1H, CHH), 4.39-4.61 (m, 3H, CHH, CH2), 5.11 (dd, J=4.9, 13.2 Hz, 1H, CH), 6.88-7.04 (m, 1H, Ar), 7.15-7.32 (m, 1H, Ar), 7.34-7.50 (m, 2H, Ar), 7.54 (s, 1H, NH), 7.58 (t, J=5.8 Hz, 1H, NH), 7.71 (d, J=7.7 Hz, 1H, Ar), 8.17 (d, J=6.0 Hz, 2H, Ar), 10.98 (s, 1H, NH); 13C NMR (DMSO-d6) δ 22.50, 31.21, 42.83, 47.14, 51.59, 120.86, 121.28, 122.01, 122.61, 123.03, 127.00, 127.45, 129.08, 130.44, 136.57, 142.48, 144.30, 154.83, 167.92, 171.00, 172.85; LCMS: MH=427/429; Anal Calcd for C21H19N4O4Cl: C, 59.09; H, 4.49; N, 13.13; Cl, 8.31. Found: C, 58.86; H, 4.26; N, 12.88; Cl, 8.32.
