[NH2:1][C:2]1[C:3]([NH:12][CH2:13][CH:14]([O:17][CH3:18])[O:15][CH3:16])=[C:4]([CH:9]=[CH:10][CH:11]=1)[C:5]([O:7][CH3:8])=[O:6].OOS([O-])=O.[K+].[CH:25](=O)[CH:26]([CH3:28])[CH3:27]>CN(C=O)C.O>[CH3:16][O:15][CH:14]([O:17][CH3:18])[CH2:13][N:12]1[C:3]2[C:4]([C:5]([O:7][CH3:8])=[O:6])=[CH:9][CH:10]=[CH:11][C:2]=2[N:1]=[C:25]1[CH:26]([CH3:28])[CH3:27]To a stirred solution of methyl 3-amino-2-(2,2-dimethoxyethylamino)benzoate (0.5 g, 2.0 mmol) from Step C of Example 13 in DMF (15 mL) and H2O (0.5 mL) were added oxone (0.8 g, 1.3 mmol) and iso-butyraldehyde (0.2 mL, 2.2 mmol) and the reaction was stirred overnight at room temperature. The reaction mixture was washed with saturated aqueous sodium bicarbonate, re-extracted with methylene chloride, dried (Na2SO4), filtered, and concentrated under reduced pressure. The crude material was purified by column chromatography (silica gel, 0% to 30% ethyl acetate in hexanes) to afford methyl 1-(2,2-dimethoxyethyl)-2-isopropyl-1H-benzo[d]imidazole-7-carboxylate (0.5 g, 85%): 1H NMR (500 MHz, DMSO-d6) δ 7.79 (dd, J=8.0, 1.0 Hz, 1H), 7.56 (dd, J=7.5, 1.0 Hz, 1H), 7.22 (t, J=8.0 Hz, 1H), 4.61 (d, J=5.0 Hz, 2H), 4.38 (t, J=5.0 Hz, 1H), 3.90 (s, 3H), 3.38-3.33 (m, 1H), 3.19 (s, 6H), 1.32 (d, J=7.0 Hz, 6H); MS (ESI+) m/z 306 (M+H).
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