Reaction Steps
1,8-Diazabicyclo[5.4.0]undec-7-ene (1.0 g, 6.6 mmol) was added to a stirred suspension of 4-aminomethyl-2-(2,6-dioxo-piperidin-3-yl)-isoindole-1,3-dione hydrochloride (0.7 g, 2.0 mmol) in acetonitrile (40 mL). After stirring for 10 minutes, 1,5-dimethyl-1H-pyrazole-3-carbonyl chloride (0.4 g, 2.6 mmol) was added. The mixture was stirred at room temperature overnight. The mixture was concentrated, and the residue was dissolved in CH2Cl2 (80 mL). The CH2Cl2 solution was washed with water (2×30 mL) and brine (30 mL), and dried (MgSO4). Solvent was removed, and the residue was purified by chromatography (SiO2, CH2Cl2: CH3OH 97.5:2.5) to give 1,5-dimethyl-1H-pyrazole-3-carboxylic acid [2-(2,6-dioxo-piperidin-3-yl)-1,3-dioxo-2,3-dihydro-1H-isoindol-4-ylmethyl]-amide (0.3 g, 38%) as a white solid: mp 213-215° C.; 1H NMR (DMSO-d6) δ 2.05-2.09 (m, 1H), 2.28 (s, 3H), 2.50-2.64 (m, 2H), 2.84-2.97 (m, 1H), 3.79 (s, 3H), 4.86 (d, J=5.9 Hz, 2H), 5.13-5.20 (dd, J=5.1 and 12.4 Hz, 1H), 6.44 (s, 1H), 7.65-7.79 (m, 3H), 8.69 (t. J=5.9 Hz, 1H), 11.15 (s, 1H); 13C NMR (DMSO-d6) δ 10.66, 21.97, 30.93, 36.39, 37.80, 48.86, 105.53, 121.71, 127.01, 131.51, 132.78, 134.70, 139.60, 140.35, 144.26, 161.91, 167.00, 167.56, 169.83, 172.75; Anal. calcd. for C20H19N5O5+0.4H2O: C, 57.66; H, 4.79; N, 16.81. Found: C, 57.85; H, 4.80; N, 16.64.
