Trifluoroacetic acid → 4-(2-Trifluoromethyl-phenoxy)-piperidine trifluoracetate

Participants

Reaction Steps

To a stirred solution of 2-trifluoromethyl-phenol (1 g, 0.00617 mole) in DMF (10 mL) was added cesium carbonate (4.01 g, 0.0123 mole), followed by 4-methanesulfonyloxy-piperidine-1-carboxylic acid tert-butyl ester (1.72 g, 0.00616 mole). The reaction mixture was heated at 60° C. overnight. The mixture was then diluted with water and the product was extracted with ethyl acetate. The ethyl acetate layer was washed with brine solution, dried over sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by column chromatography using silica gel 60-120 mesh (0.1% ethyl acetate in hexane) to afford 0.72 g (34%) of 4-(2-trifluoromethyl-phenoxy)-piperidine-1-carboxylic acid tert-butyl ester. LCMS: 346.16 (M+1)+, 94.42%. A solution of 4-(2-trifluoromethyl-phenoxy)-piperidine-1-carboxylic acid tert-butyl ester (0.72 g, 0.00208 mole) in dichloromethane was stirred at 0-5° C. To the cold solution was added TFA (1 mL) dropwise and stirring was continued at 10° C. for 2 hours. The reaction mixture was concentrated under reduced pressure and the resulting residue was washed with ether and dried to afford 0.22 g (99%) of 4-(2-trifluoromethyl-phenoxy)-piperidine trifluoracetate. LCMS: 360.1 (M+1)+, 99.3%, 1H NMR (CDCl3): δ 8.9-8.5 (bd, 2H), 7.62-7.6 (d, 1H), 7.56-7.46 (t, 1H), 7.1-7.02 (t, 1H), 7.0-6.94 (d, 1H), 5.0-4.8 (m, 1H), 3.5-3.3 (s, 4H), 2.3-2.2 (s, 4H).

Provenance & Evidence