Dichloromethane → 1H-Benzimidazole-7-carboxamide,2-(4-hydroxyphenyl)-

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Reaction Steps

Under an argon atmosphere 1M boron tribromide in dichloromethane (3.8 ml, 3.79 mmol) was transferred to a flask containing 2-(4'-methoxyphenyl)benzimidazole-4-carboxamide (NU 1076 from Example 5) (202.4 mg, 0.758 mmol). The resulting solution was refluxed for 24 hours using an air condenser. The solvent was removed by distillation to complete dryness. The solid residue was treated with 10% NaOH (10 ml), followed by dropwise addition of concentrated hydrochloric acid to neutralise (pH 7). The white precipitate was collected by filtration and dissolved in ethyl acetate (10 ml). The organic solvent was washed with water (2×3 ml), dried over MgSO4, and the product was obtained by removal of the solvent under reduced pressure. (109.5 mg, 57%). mp 266-267° C.; Found C, 63.27, H 4.37; N 15.67; C14H11N3O2. 0.75 MeOH requires C, 63.04; H, 4.69; N, 15.76; vmax (cm-1) 3424.01, 3384.16, 3309.20, 3249.55, 3155.62, 1642.35, 1618.02, 1594.50, 1577.74; δH 7.03-7.07 (2H, d, J=8.5), 7.34-7.42 (1H, t), 7.75-7.79 (1H, d), 7.85 (1H, br s), 7.90-7.94 (1H, d), 8.15-8.19 (2H, d, J=8.5), 9.4-9.6 (1H, br s), 10.0-10.4 (1H, br s), 13.0-13.4 (1H, br s); m/z (EI) 253 (M+), 236, 208, 93.

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