Reaction Steps
A solution of 5-{[2-(2,6-dioxo-piperidin-3-yl)-1,3-dioxo-2,3-dihydro-1H-isoindol-5-ylmethyl]-carbamoyl}-pentanoic acid tert-butyl ester (0.85 g, 1.8 mmol) in formic acid (25 mL) was stirred at room temperature for 90 minutes. The mixture was evaporated under vacuum, and the residue was triturated in ether/ethyl acetate and filtered, providing 0.66 g, in 88% yield; mp 144-146° C.; HPLC, Waters Symmetry C-18, 3.9×150 mm, 5 μm, 1 mL/min, 240 nm, 20/80 CH3CN/0.1% H3PO4, 4.15 (95.81%); 1H NMR (DMSO-d6) δ 1.44-1.59 (m, 4H), 2.02-2.09 (m, 1H), 2.16-2.24 (m, 4H), 2.46-2.63 (m, 2H), 2.83-2.95 (m, 1H), 4.43 (d, J=6.0 Hz, 2H), 5.14 (dd, J=12.9 Hz, J=5.4 Hz, 1H), 7.72-7.77 (m, 2H), 7.87 (d, J=7.8 Hz, 1H), 8.51 (t, J=6.0 Hz, 1H), 11.12 (s, 1H), 12.00 (s, 1H); 13C NMR (DMSO-d6) δ 22.0, 24.1, 24.7, 30.9, 33.3, 34.9, 41.9, 48.9, 121.9, 123.5, 129.7, 131.6, 133.3, 147.8, 167.0, 167.1, 169.8, 172.2, 172.7, 174.3; Anal. Calcd for C20H21N3O7+0.2H2O: C, 57.33; H, 5.13; N, 10.03. Found: C, 57.33; H, 4.89; N, 9.81.
