[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([N:8]2[CH:12]=[C:11]([CH:13]3OCC[O:14]3)[N:10]=[C:9]2[CH3:18])=[CH:4][CH:3]=1.C12(CS(O)(=O)=O)C(C)(C)C(CC1)CC2=O>C1COCC1.O>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([N:8]2[CH:12]=[C:11]([CH:13]=[O:14])[N:10]=[C:9]2[CH3:18])=[CH:6][CH:7]=1A solution of 1-(4-chlorophenyl)-4-(1,3-dioxolan-2-yl)-2-methyl-1H-imidazole (1.05 g, 3.97 mmol) and camphorsulfonic acid (92 mg, 0.40 mmol, 0.1 equiv) in THF (26.5 mL) and water (13.3 mL) was heated at 60° C. for 1 hour. The reaction was then cooled to room temperature and quenched with saturated aqueous sodium bicarbonate (100 mL). The mixture was extracted with ethyl acetate (100 mL) and the organic layer was washed with saturated aqueous sodium chloride (50 mL), dried (Na2SO4), filtered, and concentrated in vacuo. Silica gel column chromatography (EtOAc with 7% methanol) provided 1-(4-chlorophenyl)-2-methyl-1H-imidazole-4-carbaldehyde (0.600 g, tan solid) in 69% yield. 1H NMR (400 MHz, CDCl3) δ 9.89 (s, 1H), 7.67 (s, 1H), 7.53 (d, J=8.7 Hz, 2H), 7.27 (d, J=8.7 Hz, 2H), 2.40 (s, 3H). MS m/z 221.0 (M+H)+; Rt-0.47 min.
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