Water → 1-Methyl-2-(2-nitrophenyl)-benzimidazole-4-carboxaldehyde ethylene acetal

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Reaction Steps

A solution of 2-(2-nitrophenyl)-benzimidazole-4-carboxaldehyde ethylene acetal 5 (4.53 g, 14.6 mmol) in dry THF (20 mL) was added to a stirring suspension of NaH (0.640 g, 60% dispersion in mineral oil, 16.0 mmol) in dry THF (50 mL) at 0° C. under N2. The mixture was then allowed to warm to room temperature for 1 hour resulting in an orange solution. Methyl iodide (4.58 mL, 72.8 mmol) was syringed into the above mixture at room temperature under N2. This mixture was stirred for 24 hours under N2 to give a yellow mixture. Water was added and the aqueous layer was extracted with CHCl3. The combined extracts were washed with brine and dried over Na2SO4. After rotary evaporation, the resulting residue was purified by column chromatography on silica gel using Et2O:CH2Cl2 (3:1) as the eluent to give the title compound. (3.53 g, 74%). 1H NMR (CDCl3): δ 3.58 (s, 3H), 4.02-4.19 (m, 4H), 6.55 (s, 1H), 7.33-7.41 (m, 1H), 7.52-7.56 (m, 1H), 7.62-7.75 (m, 4H), 8.19 (d, J=1.7, 7.9 Hz, 1H); HRMS: Calcd. for C17H15N3O4 325.1062, found 325.1050.

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