tert-Butyl 4-oxopiperidine-1-carboxylate → Tert-butyl 4-(3,3,3-trifluoropropylidene)piperidine-1-carboxylate

Participants

Reaction Steps

To a solution of triphenyl(3,3,3-trifluoropropyl)phosphanium bromide (Intermediate 213, 972 mg, 2 mmol) in THF (20 mL) at 0 C under nitrogen was added potassium tert-butoxide (235 mg, 2.1 mmol). The resulting reaction mixture was stirred at 0 C for 15 min and then a solution of 4-oxo-piperidine-1-carboxylic acid tert-butyl ester (398 mg, 2 mmol) in THF (5 mL) was added. The solution was stirred for a further 1 h at 0 C and then evaporated to dryness. The resulting residue was dissolved in EtOAc (25 mL) and washed with water (2×25 mL). Combined organics were washed with brine, dried over magnesium sulfate and evaporated to dryness. The crude solid was dissolved in diethyl ether (50 mL) and then filtered to remove insoluble impurities. The filtrate was evaporated to dryness to afford tert-butyl 4-(3,3,3-trifluoropropylidene)piperidine-1-carboxylate (Intermediate 212, 0.99 g, triphenylphosphine detected as impurity) which was used without further purification.

Provenance & Evidence