5-Nitrofurfural → 5-[(5,6-Dichloro-1H-benzimidazol-2-yl)sulfanyl]furan-2-carbaldehyde

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Reaction Steps

5,6-Dichloro-1H-benzimidazole-2-thiol (1.0 g, 4.56 mmol) is suspended into 50 mL of tetrahydrofuran under argon. Then, 0.33 g (6.85 mmol) of sodium hydride is added. The reaction mixture is stirred at room temperature until gas evolution has ceased. 5-Nitro-2-furaldehyde (0.64 g, 4.57 mmol) is then added and the reaction mixture is stirred at room temperature for 1 h, upon which it is poured on ice and extracted 3 times with ethyl acetate. The organic extracts are combined, washed with brine, dried on magnesium sulfate, filtered and concentrated under reduced pressure. The residue is purified by chromatography on a prepacked 200 g 15-40 μm silica gel cartridge (eluting solvent: ethyl acetate/cyclohexane 50/50 v/v; rate: 50 mL/min). The fractions containing the desired product are combined and concentrated to dryness under reduced pressure. The residue is triturated in diisopropyl ether, filtered and dried under reduced pressure. 0.93 g of 5-(5,6-dichloro-1H-benzimidazol-2-ylsulfanyl)-furan-2-carbaldehyde is obtained as a yellow powder. mp: 170° C.

Provenance & Evidence