O-Phenylenediamine → Benzimidazole, 2-butyl-

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Reaction Steps

To a solution of o-phenylenediamine (0.171 g, 1.58 mmol) in absolute ethanol (8 ml), ethyl valerylimidate (0.313 g, 1.9 mmol) was added, and the mixture was refluxed overnight. The reaction was cooled to room temperature and concentrated in vacuo. The residue was partitioned between ethyl acetate and saturated NaHCO3. The organic phase was separated and the aqueous layer was extracted with ethyl acetate (3×20 ml). The organic layers were combined and washed with brine, dried (MgSO4), and then concentrated in vacuo. The crude product, thus obtained, was purified by medium pressure liquid chromatography (MPLC) on silica-gel using ethyl acetate-hexane (1:1) to give cream colored crystalline solid (0.19 g, 69%).

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