1-benzyl-N-methoxy-N-methylpiperidine-4-carboxamide → 1-(1-Benzylpiperidin-4-yl)pent-4-en-1-one

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Reaction Steps

A solution of 1-benzyl-N-methoxy-N-methylpiperidine-4-carboxamide (8.88 g, 33.0 mmol) in THF (40 mL, 0.8 M) was cooled to 0° C. and treated with a 0.5 M solution of 3-butenylmagnesium bromide (51 mmol, 102 mL) in a dropwise manner. After stirring for 4 h the reaction was quenched with 1 N HCl (24 mL), neutralized with 5% aqueous sodium bicarbonate and diluted with ethyl acetate. The layers were separated and the aqueous phase was extracted with ethyl acetate. The combined organic layers were washed with saturated aqueous sodium chloride, dried over MgSO4, and concentrated in vacuo. The residue was chromatographed on silica (2-20% methanol in dichloromethane) to afford the desired product (4.95 g, 57%). Rf 0.22 (10% MeOH/CH2Cl2). 1H NMR (CDCl3, 300 MHz) δ 7.38-7.21 (m, 5H), 5.82-5.76 (m, 1H), 5.15-4.95 (m, 2H), 3.50 (s, 2H), 2.91 (d, J=11.2 Hz, 2H), 2.54 (t, J=7.3 Hz, 2H), 2.39-2.23 (m, 3H), 2.06-1.97 (m, 2H), 1.82-1.61 (m, 4H). ESI MS found for C17H23NO m/z [258.2 (M+1)].

Provenance & Evidence