C[O:2][C:3]1[C:8]([N:9]2[C:13](=[O:14])[C:12]3=[CH:15][CH:16]=[CH:17][CH:18]=[C:11]3[C:10]2=[O:19])=[CH:7][CH:6]=[C:5]([O:20][CH3:21])[N:4]=1.[BrH:22].CCOCC>C(O)(=O)C>[BrH:22].[O:19]=[C:10]1[C:11]2[C:12](=[CH:15][CH:16]=[CH:17][CH:18]=2)[C:13](=[O:14])[N:9]1[C:8]1[C:3]([OH:2])=[N:4][C:5]([O:20][CH3:21])=[CH:6][CH:7]=11,3-Dioxo-2-(2-hydroxy-6-methoxypyridin-3-yl)-isoindoline hydrobromide (6) was prepared and isolated as follows. To a flask were added 2,6-dimethoxy-3-phthalimidopyridine (155 mg, 0.546 mmol) and hydrogen bromide solution in acetic acid (30%, 6 ml). The mixture was stirred at room temperature under N2 for 18 h. Dry ether was added slowly until the solution became cloudy. White crystals were precipitated, filtered and washed with ether and ethyl acetate to afford 6 (127 mg, 67%) as white powdery crystals: mp 250° C.; 1H NMR (DMSO-d6) δ 7.97-7.94 (m, 2H), 7.91-7.88 (m, 2H), 7.64 (d, J=8.2 Hz, 1H), 6.25 (d, J=8.2 Hz, 1H), 3.86 (s, 3H); 13C NMR (DMSO-d6) δ 167.5, 162.1, 159.1, 142.8, 135.4, 132.1, 123.7, 108.2, 96.4, 54.8; MS (CI/CH4) 270 [M]+.
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