Pyridine → Tert-butyl 3-(5-(4-fluorophenyl)oxazol-2-yl)piperidine-1-carboxylate

Participants

Reaction Steps

Dry pyridine (0.24 mL, 2.74 mmol) was added dropwise to a solution of tert-butyl 3-((2-(4-fluorophenyl)-2-oxoethyl)carbamoyl)piperidine-1-carboxylate (500 mg, 1.37 mmol) in dry CH2Cl2 (12 mL) at 0° C., followed by trifluoromethanesulfonic anhydride (0.5 mL, 2.74 mmol). The reaction mixture was allowed to warm up to room temperature and stirred for 3 h. The reaction mixture was diluted with CH2Cl2 and the organic layer was washed with water and brine, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The crude product was purified by purified by column chromatography (silica gel 60-120 mesh, eluent 12-15% EtOAc in petroleum ether) to afford tert-butyl 3-(5-(4-fluorophenyl)oxazol-2-yl)piperidine-1-carboxylate (150 mg, yield 32%). 1H NMR (400 MHz, DMSO-d6) δ 7.75-7.72 (dd, J=9.0 Hz, 5.3 Hz, 2H), 7.55 (s, 1H), 7.33-7.29 (t, J=8.8 Hz, 2H), 3.99-3.90 (m, 1H), 3.69-3.60 (m, 1H), 3.02 (m, 1H), 2.12-2.07 (m, 1H), 1.82-1.76 (m, 2H), 1.64-1.57 (m, 1H), 1.51-1.42 (m, 2H), 1.35 (s, 9H). MS (ESI) m/z: Calculated for C19H23FN2O3: 346.17. found: 347.2 (M+H)+

Provenance & Evidence