To a stirred mixture of 3-(5-aminomethyl-1-oxo-1,3-dihydro-isoindol-2-yl)-piperidine-2,6-dione methane sulfonate (0.43 g, 1.16 mmol) and cyclohexylisocyanate (0.148 mL, 1.16 mmol) in acetonitrile (8 mL), was added triethylamine (0.32 mL, 2.33 mmol) at room temperature under nitrogen. After 2 h, dil. aq. HCl (10 mL) was added. The solids were collected by filtration and washed with dil. aq. HCl (20 mL) and acetonitrile (10 mL). The product was dried in vacuo to give 1-cyclohexyl-3-[2-(2,6-dioxo-piperidin-3-yl)-1-oxo-2,3-dihydro-1H-isoindol-5-ylmethyl]-urea as a white solid (0.24 g, 52% yield): HPLC: Waters Nova-Pak C18 column, 3.9×150 mm, 4 μm; 25/75 CH3CN/0.1% aq H3PO4, 10 min, 1.0 mL/min, 5.94 min (99.50%); mp: 265-267° C.; 1H NMR (DMSO-d6) δ 0.99-1.36 (m, 5H, CH2, CH2, CH), 1.44-1.84 (m, 5H, CH2, CH2, CH), 1.92-2.06 (m, 1H, CH), 2.25-2.47 (m, 1H, CH), 2.59 (d, J=17.4 Hz, 1H, CH), 2.82-3.02 (m, 1H, CH), 3.33-3.47 (m, 1H, CH), 4.22-4.50 (m, 4H, CH2 and CH2), 5.10 (dd, J=5.0, 13.3 Hz, 1H, NCH), 5.88 (d, J=7.9 Hz, 1H, NH), 6.29 (t, J=5.9 Hz, 1H, NH), 7.38 (d, J=7.7 Hz, 1H, Ar), 7.44 (s, 1H, Ar), 7.67 (d, J=7.7 Hz, 1H, Ar), 10.98 (s, 1H, NH); 13C NMR (DMSO-d6) δ 22.49, 24.49, 25.28, 31.20, 33.28, 42.86, 47.09, 47.89, 51.55, 121.76, 122.84, 126.81, 130.13, 142.30, 145.51, 157.26, 167.98, 170.99, 172.85; LCMS: MH=399; Anal Calcd for C21H26N4O4: C, 63.30; H, 6.58; N, 14.06. Found: C, 63.30; H, 6.51; N, 13.76.
