[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[N:7]([CH:11]1[CH2:15][CH2:14][NH:13][CH2:12]1)[CH2:6][CH2:5]2.C=O.[C:18](O)(=O)C.[BH3-]C#N.[Na+].[OH-].[Na+]>CO>[Br:1][C:2]1[CH:3]=[C:4]2[C:8](=[CH:9][CH:10]=1)[N:7]([CH:11]1[CH2:15][CH2:14][N:13]([CH3:18])[CH2:12]1)[CH2:6][CH2:5]2A solution of compound 2 (1.0 g, 3.743 mmol) in dry methanol (10 mL) was treated with HCHO (0.36 g, 4.491 mmol, 37% in water) followed by acetic acid (0.53 mL, 9.357 mmol) and NaCNBH3 (0.28 g, 4.491 mmol) at room temperature and the resulting mixture was stirred for over night (14 h). The reaction was basified with 2 N NaOH solution (50 mL) and product was extracted into CH2Cl2 (2×25 mL). The combined organic layer was washed with brine (15 mL) and dried (Na2SO4). Solvent was evaporated and crude was purified by column chromatography (2 M NH3 in methanol:CH2Cl2, 5:95) to obtain compound 3 (0.7 g, 66.6%) as a syrup. 1H NMR (CDCl3) δ 7.12-7.08 (m, 2H), 6.35 (d, 1H, J=9.0 Hz), 4.19-4.10 (m, 1H), 3.45-3.39 (m, 2H), 2.91 (t, 2H, J=8.1 Hz), 2.70-2.63 (m, 3H), 2.51-2.43 (m, 1H), 2.34 (s, 3H), 2.19-2.07 (m, 1H), 1.93-1.81 (m, 1H); ESI-MS (m/z, %): 281, 283 (MH+, 100).
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