Reaction Steps
To a stirred mixture of 2-amino-4,5-dimethoxybenzoic acid (5.0 g, 25 mmol) and imidazole (2.1 g, 30 mmol) in acetonitrile (50 mL), was added acetyl chloride (2.2 mL, 30 mmol) at room temperature. The mixture was stirred at room temperature overnight. To the mixture, was added 3-amino-piperidine-2,6-dione hydrogen chloride (4.2 g, 25 mmol), imidazole (3.8 g, 56 mmol) and triphenyl phosphite (7.3 mL, 28 mmol) and heated to reflux for 22 hours. The suspension was filtered and washed with acetonitrile (50 mL) and water (2×50 mL) to give a solid. The solid was stirred in sodium hydrogen carbonate (sat, 50 mL), and water (50 mL) for 1 hour. The suspension was filtered and washed with water (2×50 mL) and ethyl acetate (30 mL) to give 3-(6,7-dimethoxy-2-methyl-4-oxo-4H-quinazolin-3-yl)-piperidine-2,6-dione as a white solid (5.7 g, 68% yield): HPLC: Waters Symmetry C18, 5 μm, 3.9×150 mm, 1 mL/min. 240 nm, 20/80 CH3CN/0.1% H3PO4, 3.26 min (99.8%); mp: 325° C. (decomp); 1H NMR (DMSO-d6) δ 2.15-2.19 (m, 1H, CHH), 2.56-2.88 (m, 6H, CH3, CH2, CHH), 3.85 (s, 3H, CH3), 3.90 (s, 3H, CH3), 5.22 (dd, J=5, 11 Hz, 1H, NCH), 7.09 (s, 1H, Ar), 7.35 (s, 1H, Ar), 10.99 (s, 1H, NH); 13C NMR (DMSO-d6) δ 21.12, 23.21, 30.62, 55.63, 55.97, 56.38, 104.98, 107.31, 113.27, 143.09, 148.40, 153.24, 154.83, 159.76, 169.61, 172.64; LCMS: MH=332; Anal Calcd for C16H17N3O5: C, 58.00; H, 5.17; N, 12.68. Found: C, 57.88; H, 5.06; N, 12.77.
