Potassium Carbonate → cis-1-(4-Bromobenzyl)-3,5-dimethylpiperidine

Participants

Reaction Steps

A suspension of 4-bromobenzyl bromide (4.0 g, 16.0 mmol), cis, trans-(3,5-dimethylpiperidine) (1.81 g, 16.0 mmol) and potassium carbonate (2.65 g, 19.2 mmol) in THF (160 mL) was heated under reflux for 24 h. The reaction mixture was allowed to cool to ambient temperature, the solid removed by filtration and the filtrate evaporated in vacuo. The resultant residue was loaded onto a 50 g SCX-2 cartridge which was washed with methanol then eluted with 2N ammonia in methanol. Concentration of the combined basic fractions in vacuo followed by flash chromatography of the resultant residue (silica, 330 g column, ISCO, 0-25% ethyl acetate in pentane) afforded cis-1-(4-bromobenzyl)-3,5-dimethylpiperidine (1.60 g, 35%) as a colourless oil. 1H NMR (CDCl3, 300 MHz): 7.47-7.39 (m, 2H); 7.20 (d, J=8.0 Hz, 2H); 3.42 (s, 2H); 2.82-2.71 (m, 2H); 1.76-1.61 (m, 4H); 1.51-1.37 (m, 2H); 0.82 (d, J=6.4 Hz, 6H).

Provenance & Evidence