Reaction Steps
1,8-Diazabicyclo[5,4,0]undec-7-ene (1.0 g, 6.8 mmol) was added to a stirred suspension of 4-aminomethyl-2-(2,6-dioxo-piperidin-3-yl)-isoindole-1,3-dione hydrochloride (1.0 g, 3.1 mmol) in acetonitrile (50 mL). The mixture was stirred for 30 minutes, then added slowly to a stirred solution of triphosgen (0.3 g, 1.1 mmol) in acetonitrile (20 mL) over 20 minutes. After stirring for another 10 minutes, a solution of dimethylamine/THF (2.0 M, 1.6 mL, 3.1 mmol) and diidopropylethylamine (0.5 g, 3.7 mmol) was added in one portion. The mixture was stirred at room temperature overnight. The mixture was concentrated, and the residue was dissolved in methylene chloride (80 mL). The methylene chloride solution was washed with 1N HCl (40 mL), water (40 mL), and brine (40 mL), and dried (MgSO4). Solvent was removed and purified by chromatography (silica gel) to give 3-[2-(2,6-dioxo-piperidin-3-yl)-1,3-dioxo-2,3-dihydro-1H-isoindol-4-ylmethyl]-1,1-dimethyl-urea (0.4 g, 36%) as a white solid: mp 143-145° C.; 1H NMR (DMSO-d6) δ 2.04-2.08 (m, 1H), 2.50-2.63 (m, 2H), 2.84 (s, 6H, 2CH3), 2.84-2.96 (m, m, 1H), 4.68 (d, J=5.6 Hz, 2H, CH2), 5.11-5.18 (dd, J=5.2 and 121.5 Hz, 1H, CH), 6.98 (t, J=5.6 Hz, 1H, NH), 7.69-7.85 (m, 3H, Ar), 11.13 (s, 1H, NH); 13C NMR (DMSO-d6) δ 21.98, 30.93, 35.88, 39.30, 48.82, 121.45, 126.75, 131.38, 132.92, 134.56, 141.44, 148.14, 167.06, 167.63, 169.84, 172.75; Anal. calcd. for C17H18N4O5: C, 56.98; H, 5.06; N, 15.63. Found: C, 56.87; H, 5.16; N, 15.16.
