Trifluoroacetic acid → HCID 18538456, compound

Participants

Reaction Steps

To a solution of 1-tert-butoxycarbonyl-4-hydroxypiperidine (1.01 g, 5.0 mmol) in dry THF (30 mL) were added triphenylphosphine (2.0 g, 7.5 mmol) and 5-methyl-1,3,4-thiadiazol-2-thiol (0.79 g, 6.0 mmol). To the mixture was added diisopropyl azodicarboxylate (1.2 mL, 6.0 mmol) under ice cooling, and the mixture was stirred at the same temperature for 1 hour. The reaction mixture was diluted with ethyl acetate (100 mL), which was washed with saturated aqueous solution of sodium hydrogen carbonate, aqueous solution of 1N-sodium hydroxide and saturated aqueous solution of sodium chloride. The solvent was dried over anhydrous sodium sulfate and distilled off under reduced pressure. The residue was subjected to silica gel column chromatography (50 g, ethyl acetate-hexane 1:2) to give a crude product (1.63 g). The crude product (0.82 g) was dissolved in dichloromethane (5 mL). To the solution was added trifluoroacetic acid (5 mL), and the mixture was stirred at room temperature for 30 minutes. The reaction mixture was concentrated under reduced pressure, and the concentrate was dissolved in water (20 mL) and washed twice with diethyl ether (20 mL). The solvent was distilled off under reduced pressure, and the residue was subjected to toluene azeotrope, and the resulting residue was vacuum-dried to give the titled compound as white solid substance (535 mg, 65%).

Provenance & Evidence