Trifluoroacetic acid → 4-(1-(fur-2-ylmethyl)-1H-benzimidazole-2-carbonyl)piperidine

Participants

Reaction Steps

Combine 1-(t-butoxycarbonyl)-4-(1H-benzimidazole-2-carbonyl)piperidine (1.16 mmol), furfuryl alcohol (0.10 mL, 1.16 mmol), and triphenylphosphine (0.33 g, 1.28 mmol) in tetrahydrofuran (5 mL). Add diethyl azodicarboxylate (0.20 mL, 1.28 mmol). After 18 hours, evaporate the reaction mixture in vacuo to give a residue. Partition the residue between ethyl acetate and water. Separate the organic layer and extract with water and saturated aqueous sodium chloride solution. Dry the organic layer over Na2SO4, filter, and evaporate in vacuo to give the title compound. Chromatograph the residue on silica gel eluting with 5% acetone/dichloromethane to give 1-(t-butoxycarbonyl)-4-(1-(fur-2-ylmethyl)-1H-benzimidazole-2-carbonyl)piperidine. Cool 1-(t-butoxycarbonyl)-4-(1-(fur-2-ylmethyl)-1H-benzimidazole-2-carbonyl)piperidine (1.0 mmol), and dichloromethane (5 mL). Slowly add a cold solution of trifluoroacetic acid (1 mmol) in dichloromethane (2 mL). After 15 minutes, partition the reaction mixture between dichloromethane and saturated aqueous sodium bicarbonate solution. Separate the organic layer and extract with brine. Dry the organic layer over Na2SO4, filter, and evaporate in vacuo to give the title compound.

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