tert-Butyl 4-oxopiperidine-1-carboxylate → 1-Boc-4-Methylenepiperidine

Participants

Reaction Steps

To a solution of methyl triphenylphosphonium bromide (2.69 g, 7.5 mmol) in THF (20 mL) was n-butyllithium (1.8 M; 4.2 mL, 7.5 mmol) in hexane slowly added at −78° C. The mixture was stirred for 1 h. After this time, a solution of tert-butyl 4-oxopiperidine-1-carboxylate (1 g, 5.0 mmol) in THF (10 mL) was added dropwise to the mixture. The resultant mixture was stirred at room temperature overnight. The reaction mixture was quenched with water and extracted with isohexane (×3). The combined isohexane layers were evaporated and filtrated through a silica-plug. The crude product was purified using flash chromatography with DCM as eluent yielding 0.58 g (59%) of the title compound. HPLC purity 91%, RT=2.47 min (System A; 10-97% MeCN over 3 min); 86%, RT=2.43 min (System B; 10-97% MeCN over 3 min). 1H NMR (400 MHz, CDCl3) δ ppm 1.46 (s, 9H) 2.12-2.22 (m, 4H) 3.35-3.46 (m, 4H) 4.73 (s, 2H). MS (ESI+) for C11H19NO2 m/z 142 (M-C4H8)+. *Previously reported in J. Med. Chem. 2002, 45, 3143-3160.

Provenance & Evidence