Reaction Steps
To a solution of ethoxyacetic acid (0.8 mL, 8.5 mmol) and oxalyl chloride (0.7 mL, 8.0 mmol) in ether (5 mL) was added DMF (0.03 mL) at room temperature. After 3 h, 4-amino-2-(2,6-dioxo(3-piperidyl))isoindoline-1,3-dione (1.1 g, 4.0 mmol) and THF (40 mL) was added to the mixture. Then the mixture was heated to reflux for 15 h. To the mixture was added methanol (10 mL) to give a suspension. The suspension was filtered and washed with methanol (10 mL) to give N-[2-(2,6-dioxo-piperidin-3-yl)-1,3-dioxo-2,3-dihydro-1H-isoindol-4-yl]-2-ethoxy-acetamide as a white solid (1.3 g, 87% yield): mp, 253-255° C.; 1H NMR (DMSO-d6) δ 1.27 (t, J=7.0 Hz, 3H, CH3), 2.06-2.10 (m, 1H, CHH), 2.46-2.64 (m, 2H, CH2), 2.84-2.98 (m, 1H, CHH), 3.66 (q, J=7.0 Hz, 2H, CH2), 4.14 (s, 2H, CH2), 5.17 (dd, J=5.2, 12.7 Hz, 1H, NCH), 7.62 (d, J=7.2 Hz, 1H, Ar), 7.87 (t, J=8.2 Hz, 1H, Ar), 8.75 (d, J=8.4 Hz, 1H, Ar), 10.39 (s, 1H, NH), 1.16 (s, 1H, NH); 13C NMR (DMSO-d6) δ 14.88, 21.93, 30.92, 48.98, 66.89, 69.49, 116.00, 118.28, 124.25, 131.31, 135.99, 136.53, 166.69, 168.31, 169.49, 169.73, 174.71; Anal Calcd for C17H17N3O6: C, 56.82; H, 4.77; N, 11.69. Found C, 56.82; H, 4.71; N, 11.60.
