1,1'-Carbonyldiimidazole → 2-(4-[1,3]-Dioxolan-2-ylmethylphenyl)-1H-benzimidazole-4-carboxamide

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Reaction Steps

A solution of 4-(1,3-dioxolan-2-ylmethyl)benzoic acid (1.0 g, 4.80 mmol) in pyridine (5 mL) and N,N-dimethylformamide (5 mL) was treated with 1,1′-carbonyldiimidazole (0.856 g, 5.28 mmol) at 45° C. for 2 hours. 2,3-Diaminobenzamide dihydrochloride (synthesized as described in U.S. Pat. No. 6,737,421, column 11, EXAMPLE 2, step (e), 1.08 g, 4.80 mmol) was added and the mixture stirred at ambient temperature overnight. The mixture was concentrated and the residue heated in acetic acid (30 mL) at 80° C. for 3 hours. After cooling, the mixture was concentrated and the residue partitioned between ethyl acetate and sodium bicarbonate solution. After filtering, the filtrate was concentrated and the residue purified by flash chromatography on silica gel (0-15% methanol in 2:1 ethyl acetate/hexane) to give 1.14 g of the title compound. MS (DCI) m/z 324 (M+H)+.

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