Sodium hydride → 1-(Tert-butoxycarbonyl)-4-(3-oxo-3-phenylprop-1-enyl)piperidine

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Reaction Steps

Diethyl (2-oxo-2-phenylethyl)phosphonate (0.255 mL, 301 mg, 1.17 mmol) was added in one portion to a stirred suspension of sodium hydride (60% oil dispersion, 45 mg, 1.13 mmol) in THF (7 mL) at rt. After 15 min, a portion (1.8 mL) of the clear solution was removed and discarded, and the remainder cooled in an ice bath. 1-(tert-Butoxycarbonyl)-4-piperidinecarboxaldehyde (177 mg, 0.830 mmol, from Step B) was added in THF (1.0 mL) with additional THF (2×1.0 mL) for rinsing. After 16 h at rt, the mixture was then partitioned between ether (40 mL) and 2.5 N aq. NaOH (20 mL). The organic layer was washed with sat'd NaCl (20 mL), dried (Na2SO4), decanted, and evaporated. The crude product was purified by flash column chromatography on silica gel, eluting with 10% EtOAc in hexane, to give 201 mg of 1-(tert-butoxycarbonyl)-4-(3-oxo-3-phenylprop-1-enyl)piperidine as a colorless oil. Hydrogenation of this material using 5% Pd/C in 95% ethanol at atmospheric pressure yielded the title compound as a white crystalline solid.

Provenance & Evidence